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UBC Theses and Dissertations

Studies in mink nutrition with special reference to supplementary protein sources Ebner, Kurt Euwald 1957

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STUDIES IN MINK NUTRITION WITH SPECIAL REFERENCE TO SUPPLEMENTARY PROTEIN SOURCES by KURT EUWALD EBNER &.S .A. ( H o n o u r s ) , U n i v e r s i t y of B r i t i s h C o l u m b i a , 1955 k- THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE IN AGRICULTURE i n the D i v i s i o n o f A n i m a l S c i e n c e We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d Members of t h e D i v i s i o n THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1957 v ABSTRACT The p r i m a r y o b j e c t i v e of t h i s s t u d y was t o compare horse meat, whale meat, c h i c k e n wastes and h e r r i n g as s u p p l e -mentary a n i m a l p r o t e i n s o u r c e s i n r a t i o n s f o r mink d u r i n g main-t e n a n c e , r e p r o d u c t i o n and growth. P a r t of t h e r a t i o n s were canned and p a r t of the r a t i o n s c o n t a i n e d a c o m m e r c i a l a n t i o x -i d a n t . The r e s u l t s of t h e maintenance e x p e r i m e n t i n d i c a t e d 'that t h e r e were no s t a t i s t i c a l d i f f e r e n c e s between the r a t i o n s . * I n t h e r e p r o d u c t i v e phase of the e x p e r i m e n t , th e mink r e c e i v i n g the canned r a t i o n s had almost complete r e p r o d u c t i v e f a i l u r e whereas the mink r e c e i v i n g the f r o z e n r a t i o n s had a k i t c r o p t h a t was below a v e r a g e . • There were s i g n i f i c a n t d i f f e r e n c e s between t h e r a t i o n s i n the growth phase of the e x p e r i m e n t . The r a t i o n s c o n t a i n i n g Horse Meat, Whale Meat and C h i c k e n Waste A were s u p e r i o r t o those c o n -t a i n i n g C h i c k e n Waste B and H e r r i n g . The d i f f e r e n c e between the two c h i c k e n wastes has been a t t r i b u t e d t o t h e v a r i a b i l i t y o f t h e c o m p o s i t i o n of c h i c k e n w aste. The below average performance of the mink r e c e i v i n g t h e H e r r i n g r a t i o n was not due t o p r o t e i n of i n f e r i o r q u a l i t y , as e v i d e n c e d by i t s h i g h Net P r o t e i n U t i l i z a t i o n v a l u e , but p r o b a b l y due t o the r e s u l t s of o x i d a t i v e r a n c i d i t y . The a d d i t i o n of the c o m m e r c i a l a n t i o x i d a n t t o the r a t i o n s had no s i g n i f i c a n t e f f e c t on the performance of the mink d u r i n g maintenance and r e p r o d u c t i o n but d i d r e t a r d t h e growth of the k i t s . The a n t i o x i d a n t f a i l e d t o p r e v e n t t h e d e s t r u c t i o n of thiamine i n the frozen and canned rations but did afford some protection for Vitamin A i n the canned r a t i o n s . The Net Protein U t i l i z a t i o n values for the f a t extrac-ted supplementary protein sources d i f f e r e d considerably. Herring was the highest and was followed by Horse Meat and Whale Meat, Chicken Waste A and Chicken Waste B. The d i g e s t i b i l i t y t r i a l s indicate l i t t l e differences between the rations except for f a t d i g e s t i b i l i t y . The high f a t d i g e s t i b i l i t y suggests that mink can u t i l i z e high levels of f a t from varying sources. The low "carbohydrate" d i g e s t i b i l i t y i n d i -cates that mink may have d i f f i c u l t y i n u t i l i z i n g the cereal portion of t h e i r r a t i o n s . The v a r i a b i l i t y i n feed consumption of the mink r e c e i v -ing the canned rations was attributed to the differences i n the di g e s t i b l e energy contents of the r a t i o n s . Regression equations r e l a t i n g feed consumption to body weight were calculated for the various r a t i o n groups. I n p r e s e n t i n g t h i s t h e s i s i n p a r t i a l f u l f i l m e n t o f t h e r e q u i r e m e n t s f o r an advanced degree at the U n i v e r s i t y o f B r i t i s h Columbia, I agree t h a t the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r r e f e r e n c e and s t u d y . I f u r t h e r agree t h a t p e r m i s s i o n f o r e x t e n s i v e c o p y i n g o f t h i s t h e s i s f o r s c h o l a r l y purposes may be g r a n t e d by t h e Head o f my Department o r by h i s r e p r e s e n t a t i v e . I t i s u n d e r s t o o d t h a t c o p y i n g o r p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l g a i n s h a l l not be a l l o w e d w i t h o u t my w r i t t e n p e r m i s s i o n . Department o f CX^/S/^A^^^Q^ S ZAJL^A^ZJZ. The U n i v e r s i t y o f B r i t i s h Columbia, Vancouver S, Canada. ACKNOWLEDGEMENT The w r i t e r w i s h e s t o than k , Dean B l y t h e E a g l e s , Chairman of the D i v i s i o n of A n i m a l S c i e n c e , f o r p r o v i d i n g the f a c i l i t i e s i n o r d e r t o conduct t h i s e x p e r i m e n t . S i n c e r e thanks a r e e x p r e s s e d t o D r . A . J . Wood, P r o f e s s o r i n t h e D i v i s i o n of A n i m a l S c i e n c e , f o r s u g g e s t i n g t h i s problem and h i s d i r e c t i o n , a s s i s t a n c e and c r i t i c i s m d u r i n g the cou r s e of t h i s s t u d y . Thanks are a l s o extended t o D r . W.D. K i t t s f o r h i s a d v i c e and c r i t i c i s m s . Thanks a re extended t o v a r i o u s s t u d e n t s who a s s i s t e d i n the m i x i n g and c a n n i n g of t h e r a t i o n s , i n p a r t i c u l a r R . J . Bose and C.B. B a i l e y . The w r i t e r a l s o w i s h t o e x p r e s s g r a t i t u d e t o Canada Mink B r e e d e r ' s A s s o c i a t i o n f o r f i n a n c i a l a s s i s t a n c e . TABLE OF CONTENTS PAGE I . I n t r o d u c t i o n 1 I I . The F o r m u l a t i o n and C o m p o s i t i o n of t h e E x p e r i m e n t a l R a t i o n s 5 1. Development of t h e C e r e a l P o r t i o n 6 2 . The Supplementary P r o t e i n S o u r c e s 8 3 . F o r m u l a t i o n of t h e B a s i c R a t i o n s 9 D e s c r i p t i o n of t h e E x p e r i m e n t a l R a t i o n s .. 1M-5. Choice of t h e A n t i o x i d a n t f o r the E x p e r i m e n t a l R a t i o n s 15 6 . M i x i n g , Canning and S t o r a g e of the R a t i o n s 18 I I I . E x p e r i m e n t a l D e s i g n 19 IV. Management 20 V. E x p e r i m e n t a l 21 1. Maintenance 21 2 . Adequacy of t h e Thiamine L e v e l i n a Canned Horsemeat R a t i o n 26 3 . R e p r o d u c t i o n 29 h. Growth 33 5 . F u r Q u a l i t y h2 6 . The D e s t r u c t i o n of Thiamine i n the E x p e r i m e n t a l R a t i o n s ^2 (a) I n t r o d u c t i o n h2 (b) The E f f e c t of P r o l o n g e d S t o r a g e a t O F . on the Thiamine Co n t e n t of the E x p e r i m e n t a l R a t i o n s .. *+5 ( c ) The D e s t r u c t i o n of Thiamine Between Thawing and F e e d i n g .. *+6 7. D i g e s t i b i l i t y S t u d i e s on t h e E x p e r i m e n t a l R a t i o n s 50 8 . The Net P r o t e i n U t i l i z a t i o n of t h e Supplementary P r o t e i n s Sources 57 9 . The R e l a t i o n s h i p Between Maintenance Feed Consumption and Body Weight i n A d u l t Mink 61 V I . Summary 75 PAGE V I I . Appendices A. Maintenance Weight Data f o r t h e Female A d u l t Mink 78 B. The H e r r i n g Mink D u r i n g Maintenance .... 79 C. Body .Weight and Feed Consumption of Male Mink R e c e i v i n g a-Canned Horse Meat and H e r r i n g R a t i o n 80 D. R e p r o d u c t i o n and Ytfeaning D a t a f o r t h e E x p e r i m e n t a l Groups 81 E. Growth D a t a f o r the E x p e r i m e n t a l Groups. 82 F. T e s t f o r S i g n i f i c a n c e W i t h i n a Group ... 85 G. P r o c e d u r e f o r Thiamine D e t e r m i n a t i o n s . . . 88 H. D i g e s t i b i l i t y S t u d i e s on. t h e F r o z e n =.. R a t i o n s 92 I . Wet P r o t e i n U t i l i z a t i o n of the, . .* < Supplementary P r o t e i n s 96 J . The R e l a t i o n s h i p Between Feed Consumption and Body Weight 102 V I I I . B i b l i o g r a p h y 103 1 I. Introduction Mink are the most important of the semi-domesticated animals raised for the production of f u r . Economical and e f f i c -ient production i s contingent upon maximum.production per unit of feed. Large l i t t e r s , heavy weaning weights, continuous and rapid growth of k i t s make for p r o f i t and are .largely the r e s u l t of adequate n u t r i t i o n . Information on the n u t r i t i o n a l require-ments of mink are scanty and are i n a continuous state,of r e v i s i o n as more information becomes a v a i l a b l e . This lack of information stems, i n part, from the r e -cent domestication of t h i s species. As with other carnivores, such as the dog and cat, there i s a surprising dearth of i n f o r -mation needed to permit formulation of adequate p r a c t i c a l r a t i o n s . Recently, The United States National Research Council has pre-pared a Recommended Nutrient Allowance for Minks ( 9 1 ) . The many incomplete sections i n t h i s publication, further t e s t i f i e s to the inadequacy of our information to date. The present study attempts to extend our limited knowledge of the n u t r i t i v e needs of t h i s animal. Of necessity, some of the work; has had to be of an exploratory nature i n the hope that the r e s u l t s might pro-vide a basis for further investigations and ultimately lead to a more precise statement of the n u t r i t i v e needs of the mink. The d i e t of the mink i s normally mixed as a semi-fluid mass and contains from 30-HO per cent dry matter. Attempts have been made to formulate dry diets but none have been developed to 2 the point that they w i l l successfully carry a mink through i t s complete l i f e cycle (2*+, 2 5 ) . The f a i l u r e s to date may have been due to the lack of e s s e n t i a l unknown factors such as those shown to be present i n l i v e r and hog mucosa ( 38 ) . L i t t l e or no back-log of basic information i s available on the mink's n u t r i t i v e needs and research i n t h i s f i e l d , of neces-s i t y , has had to follow two pathways. Investigations using syn-th e t i c diets are an e s s e n t i a l prerequisite for the determination of absolute n u t r i t i v e needs. However, such studies are l i k e l y to be time consuming and expensive. There i s much that can be learnt of d i r e c t immediate benefit to the industry from experimen-t a l work conducted on natural d i e t a r i e s . The primary objective of t h i s study has been to seek out information that would ultimately lead to the r e s o l u t i o n of the problems created by the diminishing supply and increasing cost of raw animal protein. In the past, the main source of such protein has been horse meat. Rations formulated with a high l e v e l of t h i s meat have given f a i r l y s a t i s f a c t o r y r e s u l t s . Recently, mink ranchers have been forced to look for alternative animal protein sources because the diminishing horse population has been unable to provide adequate supplies of meat to the expanding mink industry. The substitutes used include whale meat, chicken wastes, various types of f i s h , t r i p e , lungs and meat scraps. L i t t l e information i s available on the r e l a t i v e worth of these substitutes i n com-parison to horse meat and thus the primary objective of t h i s inves-3 t i g a t i o n has been to compare some of these substitutes with horse meat for maintenance, reproduction and growth of the mink. The wet diets fed to mink present chemical and microbial problems that are not encountered i n the dry rations formulated for other species. In addition, most mink rations are r e l a t i v e l y high i n f a t . The f a t t y portions of meat and f i s h products become oxidized i n the presence of l a b i l e oxygen and form hydroperoxides (27) which are capable of oxidizing such vitamins as A, D, E, Ascorbic Acid and B i o t i n (*+3j 61). In rations designed to test the r e l a t i v e worth of proteins, the destruction of such micro-nutrients might lead to reproductive and growth f a i l u r e s that could mistakenly be attributed to inadequacy of the proteins. Support for t h i s view can be found at the p r a c t i c a l l e v e l where evidence has been obtained to show that these oxidative changes may give r i s e to a var i e t y of pathological conditions i n the mink, such as "yellow f a t disease." (9) Various Vitamin E pre-parations are being used to f o r t i f y mink cereals on the assump-t i o n that they reduce the incidence of t h i s disease. The use of Vitamin E for t h i s purpose has led to confusion, for i t has not been possible to demonstrate whether the added Vitamin E i s used as a vitamin or as an antioxidant. (9) It seems u n l i k e l y that i t could be acting as a vitamin because of the high l e v e l of supplementation. If the vitamin i s serving as an antioxidant i t would seem more provident to use one of the many cheaper commer-c i a l antioxidants. Thus, a second objective of the present work I f has been to determine i f one of the commercial antioxidants would afford protection to the l a b i l e non-protein constituents of mink rations and i n so doing i n d i r e c t l y aid i n the evaluation of the proteins. The problem of spoilage i s another factor which might complicate the evaluation of the protein sources i n a wet r a t i o n . The normal wet r a t i o n provides an excellent menstruum for bac-t e r i a l growth. Severe losses have been recorded from botulism and such outbreaks have frequently been attributed to the micro-b i a l contamination carried by the animal protein sources. I f t h i s were the case i n any of the protein sources under t e s t , r e -productive or growth f a i l u r e due to b a c t e r i a l a c t i v i t y could mistakenly be attributed to an inadequacy of the proteins. In an e f f o r t to prevent such a complication a part of the rations were canned i n a manner similar to that used for commercial dog and cat feeds. 5 I I . The F o r m u l a t i o n and C o m p o s i t i o n of the E x p e r i m e n t a l R a t i o n s There i s a g r e a t v a r i e t y of d i e t s f e d t o mink. The most i m p o r t a n t i n g r e d i e n t s used i n c l u d e f i s h , r e d meats, l i v e r and c e r e a l s i n v a r i o u s p r o p o r t i o n s . Due t o the u n a v a i l a b i l i t y and h i g h c o s t of horse meat many r a n c h e r s a r e o m i t t i n g i t f r o m t h e i r r a t i o n s and are u s i n g r e p l a c e m e n t s , such as p o u l t r y by-p r o d u c t s , r a b b i t s , whale meat and o t h e r a n i m a l and v e g e t a b l e p r o t e i n s o u r c e s . Day (12) has r e c o r d e d the s e a s o n a l v a r i a t i o n i n f e e d i n g programmes i n t h e P a c i f i c N o r t h West and t h e y a r e pre-s e n t e d i n T a b l e I . T a b l e I The S e a s o n a l V a r i a t i o n of Mink F e e d i n g Programmes U.S. P a c i f i c Northwest C o n s t i t u e n t P e l t i n g t o Weaning Weaning t o P e l t i n g Per Cent Per Cent F i s h 87 t o 0 90 t o kO Red Meats 5 t o 75 0 t o 25 Beef or P o r k L i v e r 2 t o 12 0 t o 10 C e r e a l s 6 t o 15 6 t o 25 The g r e a t v a r i a t i o n i n the i n g r e d i e n t s and t h e p r o p o r -t i o n s i n w h i c h t h e y are o f f e r e d makes i t d i f f i c u l t t o f o r m u l a t e a r e p r e s e n t a t i v e r a t i o n . The e x p e r i m e n t a l r a t i o n s d e v e l o p e d f o r t h i s s t u d y c o n -s i s t e d of a c e r e a l p o r t i o n , l i v e r and a s u p p l e m e n t a r y p r o t e i n s o u r c e . Water was added t o y i e l d a f e e d h a v i n g a h a m b u r g e r - l i k e c o n s i s t e n c y . They d i f f e r f r o m the normal r a n c h mink r a t i o n s i n 6 t h a t a s i n g l e raw sou r c e of p r o t e i n was used i n s t e a d of t h e u s u a l m i x t u r e . The N a t i o n a l R e s e a r c h C o u n c i l Recommended N u t r i e n t Requirements f o r Foxes and Minks (^ -9) were used as a guide f o r the f o r m u l a t i o n of the r a t i o n s . 1. Development of the C e r e a l P o r t i o n The N a t i o n a l R e s e a r c h C o u n c i l b a s i c c e r e a l mix (H-9) was used as a guide i n f o r m u l a t i n g t h e c e r e a l p o r t i o n of t h e r a t i o n s . I t s c o n s t i t u e n t c o m p o s i t i o n i s g i v e n i n T a b l e 2 . T a b l e 2 N a t i o n a l R e s e a r c h C o u n c i l B a s i c C e r e a l M i x f o r Mink Wheat (cooked, d r i e d ) 1*+15.0 Oatmeal, cooked ^62 .0 S a l t , i o d i z e d 12 .5 Bonemeal, steamed 10 . Limestone 20.8 A l f a l f a M e a l ^5 .9 Y e a s t , Brewers 20.9 Cod L i v e r O i l 12 .5 2000.0 l b s . S e v e r a l m o d i f i c a t i o n s of t h i s mix were made b e f o r e t h e f i n a l c e r e a l mix was f o r m u l a t e d . S i n c e cooked wheat and cooked oatmeal are d i f f i c u l t t o o b t a i n i n t h i s a r e a , ground wheat and oat g r o a t s were s u b s t i t u t e d . T a b l e 3 g i v e s what might be termed a C a n a d i a n c o u n t e r p a r t f o r the U n i t e d S t a t e s recommendation g i v e n i n T a b l e 2 . 7 T a b l e 3 F i r s t R e v i s i o n of the NRC C e r e a l M i x Ground Wheat 1^-15.0 Oat G r o a t s ^62 .0 S a l t , i o d i z e d 12 .5 Bone M e a l , steamed 10.4-Limestone 20.8 A l f a l f a M e al ^ 5 . 9 Brewers Y e a s t 20.9 F i s h O i l (1500 A) 12 .5 ( *f00 D) 2000.0 l b s . S i n c e the p r i m a r y o b j e c t i v e of the p r e s e n t i n v e s t i g a t i o n was t o permit a com p a r i s o n of t h e v a r i o u s raw p r o t e i n s o u r c e s i t was n e c e s s a r y t o ensure an adequate s u p p l y of a l l the ot h e r e s s e n -t i a l n u t r i e n t s . F o r t h i s r e a s o n the N a t i o n a l R e s e a r c h C o u n c i l (U*9) type c e r e a l mix was f u r t h e r m o d i f i e d t o i n c l u d e a v a r i e t y of com-mon f e e d i n g r e d i e n t s i n the hope t h a t t h e y would p r o v i d e t h e s e o t h e r v i t a m i n s . The c e r e a l was supplemented w i t h c h o l i n e , V i t a m i n B-j_2 and f o l i c a c i d s i n c e t h e r e have been s u g g e s t i o n s t h a t t h e s e v i t a m i n s might be r e q u i r e d a t h i g h e r l e v e l s i n d i e t s r i c h i n f a t . The c o n s t i t u e n t c o m p o s i t i o n of the c e r e a l mix f i n a l l y s e l e c t e d i s g i v e n i n T a b l e d . T a b l e h C o m p o s i t i o n of t h e E x p e r i m e n t a l C e r e a l M i x Ground Wheat 680 Oat Groats 680 F i s h M e a l - H e r r i n g - 70% 2^0 Soya Bean Meal - hy% 100 Wheat B r a n 100 Dehydrated Grass M e a l 100 D r i e d H e r r i n g S o l u b l e s 30 Brewers Y e a s t 25 Limestone 20 I o d i z e d S a l t 12 .5 F i s h O i l 0.500 A) 12 .5 (l+OO/D) 2000 l b s . Supplemented/Ton 800 gm. C h o l i n e C h l o r i d e (200 gm. C h o l i n e ) . * f l b s . P r o f a c t o r B (J+0 mg. V i t . B 1 2 ) . 20 gm. Parv o (600 mg. F o l i c A c i d ) . 8 The d r y matter c o n t e n t of the c e r e a l mix was 91.*+ per c e n t . On a d r y w e i g h t b a s i s the per c e n t p r o t e i n was 2 3 . 8 ; f a t 5.-9; and ash 5 . 1 . V a r i o u s r e f e r e n c e s - were c o n s u l t e d f o r the c a l -c u l a t i o n of the proximate c o m p o s i t i o n of the c e r e a l mix ( 3 , M3, ^ 9 ) . 2 . The Supplementary P r o t e i n Sources The mink i n d u s t r y i n Canada and the U n i t e d S t a t e s i s r e l a t i v e l y new and i t s e a r l y s u c c e s s was founded i n p a r t on a s u p p l y of r e a d i l y a v a i l a b l e h orse meat. F o r t h i s r e a s o n , horse meat has become t h e s t a n d a r d a n i m a l p r o t e i n s o u r c e of the i n d u s t r y and o t h e r p r o t e i n s o u r c e s are u s u a l l y compared r e l a t i v e t o h o r s e meat. The supp l e m e n t a r y p r o t e i n s t e s t e d i n t h i s s t u d y , were whale meat, two t y p e s of c h i c k e n waste and whole h e r r i n g . C h i c k e n Waste B d i f f e r e d f r o m C h i c k e n Waste A i n t h a t i t had the g a l l b l a d d e r and a n a l p o r t i o n removed f r o m the v i s c e r a . P a r t of the c h i c k e n waste was o b t a i n e d from the U n i v e r s i t y P o u l t r y Farm and the remainder from a l o c a l f i r m . Round P a c i f i c Coast F a l l H e r r i n g was o b t a i n e d f r o m a l o c a l f i s h r e d u c t i o n p l a n t . P a c i f i c C oast Sperm Whale meat of t h e type s o l d f o r mink f e e d i n g was us e d . The f i v e supplementary p r o t e i n s o u r c e s were a n a l y z e d f o r d r y m a t t e r , f a t , ash and p r o t e i n by s t a n d a r d procedures (1>+). Great d i f f i c u l t y was encountered i n o b t a i n i n g samples w h i c h were t r u l y r e p r e s e n -t a t i v e of th e s e p r o d u c t s because of the i n h e r e n t v a r i a b i l i t y i n their c o m p o s i t i o n . The r e s u l t s of d u p l i c a t e a n a l y s i s are p r e s e n t e d i n T a b l e 5 . These v a l u e s were used f o r the c a l c u l a t i o n s of t h e b a s i c r a t i o n s on the assu m p t i o n t h a t t h e y would be i n d i c a t i v e of the average c o m p o s i t i o n . 9 T a b l e 5 P a r t i a l P r o x i m a t e C o m p o s i t i o n of the F i v e P r o t e i n Sources Per Cent of C o n s t i t u e n t P r o t e i n Source P r o t e i n F a t Ash Dry M a t t e r Wet Dry Wet Dry Wet Dry Wet Dry B a s i s B a s i s B a s i s B a s i s B a s i s B a s i s B a s i s B a s i s Horse Meat 16.3 65.0 8.0 32.0 0 .75 . 3 . 0 25 .0 100.0 Whale Meat 2h,0 80.0 5.1 17.0 O.87 2.9 30.0 100.0 C h i c k e n A 17.2 Mf.O 17.2 Mf.O 3.9 10.0 39.0 100.0 C h i c k e n B 15.9 V3.0 17.0 k6.0 3.6 9.8 37.0 100.0 H e r r i n g 17.9 69.0 5.5 21.0 2.3 8.8 26.0 100.0 3 . F o r m u l a t i o n of the B a s i c R a t i o n s F i v e b a s i c r a t i o n s were f o r m u l a t e d , one f o r each of t h e f i v e supplementary p r o t e i n s o u r c e s . An attempt was made t o f o r m -u l a t e the r a t i o n s so t h a t t h e y would be i s o c a l o r i c w i t h r e s p e c t t o p r o t e i n , f a t , and c a r b o h y d r a t e . The ash c o n t e n t was h e l d c o n -s t a n t . The r a t i o n s c o n s i s t e d of c e r e a l , l i v e r and the s u p p l e -mentary p r o t e i n s o u r c e mixed t o a h a m b u r g e r - l i k e c o n s i s t e n c y w i t h w a t e r . The N a t i o n a l R e s e a r c h C o u n c i l Recommended N u t r i e n t R e q u i r e -ments f o r Mink (k-9) s t a t e t h a t the average d r y matter of a mink r a t i o n i s 3^ per c e n t . They a l s o suggest a c e r e a l l e v e l of 20 t o 30 per cen t of t h e wet r a t i o n . T a b l e 1 s u g g e s t s t h a t many mink r a n c h e r s p r e f e r a lower c e r e a l l e v e l i n t h e i r r a t i o n s . The one 10 chosen f o r t h e f i v e b a s i c r a t i o n s was 22.5 per c e n t of the wet r a t i o n w h i c h i s 59 per cen t of the d r y r a t i o n when t h e d r y ma t t e r i s 3*+ Per c e n t . The chosen c e r e a l l e v e l was t h e n t h e lower l i m i t of the suggested N a t i o n a l R e s e a r c h C o u n c i l (^9) r a n g e . The 7 per c e n t , recommended maximum l e v e l of l i v e r (*+9) was chosen f o r the f i v e b a s i c r a t i o n s . Thus, t h e c e r e a l p o r t i o n and l i v e r have been added as a d e f i n i t e percentage of the d r y r a t i o n , 59 and 7 per c e n t r e s p e c t i v e l y . The remainder of the d r y matter t h e n a r o s e f r o m the supplementary p r o t e i n s o u r c e and any f a t or bonemeal t h a t were added t o b a l a n c e the r a t i o n s so t h e y would have t h e same p e r -centage of f a t , p r o t e i n and a s h . The N a t i o n a l R e s e a r c h C o u n c i l (^9) has recommended r a t i o n s t h a t c o n t a i n 16, 22 and 28 per c e n t p r o t e i n on a d r y we i g h t b a s i s f o r maintenance, r e p r o d u c t i o n and growth. H o w e l l (21) has shown t h a t the N a t i o n a l R e s e a r c h C o u n c i l l e v e l s are t o o low f o r maximum growth and suggest a p r o t e i n l e v e l of 32 per c e n t on a d r y w e i g h t b a s i s f o r the most e f f i c i e n t g rowth. H i g h e r l e v e l s of p r o t e i n d i d not g i v e any g r e a t e r growth. A p r o -t e i n l e v e l of 33 per cen t of the d r y r a t i o n was s e l e c t e d f o r the f i v e b a s i c r a t i o n s . A l l t he r a t i o n s were b a l a n c e d t o the 33 per cen t p r o t e i n l e v e l ( d r y b a s i s ) w i t h the r e s p e c t i v e s u p p l e m e n t a r y p r o t e i n s o u r -c e s . Now the r a t i o n s had the same p r o t e i n c o n t e n t on a d r y w e i g h t b a s i s but had d i f f e r e n t p e r c e n t a g e s of f a t , a s h , and d r y matter due t o the v a r i a t i o n of the pr o x i m a t e c o m p o s i t i o n of the s u p p l e -mentary p r o t e i n s o u r c e s (Table 5) . C h i c k e n Waste B had the h i g h e s t 11 f a t p e r c e n t a g e . T h i s b a s i c r a t i o n t h e n c o n t a i n e d 21 per cen t f a t on a d r y we i g h t b a s i s . A l l the o t h e r r a t i o n s were b a l a n c e d t o t h i s l e v e l by the a d d i t i o n of Devon Deep F r y F a t (a r e n d e r e d a n i m a l f a t used f o r deep f r y i n g ) . T h e o r e t i c a l l y , i t would have been d e s i r a b l e t o add horse f a t t o the horse r a t i o n s , c h i c k e n f a t t o t h e c h i c k e n r a t i o n s and so on but t h i s proved t o be i m p o s s i b l e . S l i g h t a d j u s t m e n t s had t o be made i n the amounts of c e r e a l and l i v e r t o r e t a i n t h e p r o t e i n p ercentage a t 33 and p e r m i t t h e f a t percentage t o be a d j u s t e d t o 21. I n a s i m i l a r manner the ash c o n -t e n t of the r a t i o n s was a d j u s t e d by the a d d i t i o n of bone meal. T h e o r e t i c a l l y , the r e s u l t i n g b a s i c r a t i o n s t h e n c o n t a i n e d on a d r y weight b a s i s 33 per cen t p r o t e i n , 21 per c e n t f a t and 6.8 per ce n t a s h . The c o n s t i t u e n t c o m p o s i t i o n of the f i v e b a s a l r a t i o n s as mixed i s g i v e n i n T a b l e 6. S i n c e the amount of f e e d r e q u i r e d over the e x p e r i m e n t a l p e r i o d was l a r g e , t h r e e s e p a r a t e m i x i n g s were made. The q u a n t i t i e s of i n g r e d i e n t s shown i n T a b l e 6 are the amounts t h a t c o u l d be c o n v e n i e n t l y mixed a t one time i n the f e e d m i x e r . The amount of water t h a t was added t o the r a t i o n s t o b r i n g them t o a h a m b u r g e r - l i k e c o n s i s t e n c y v a r i e d w i t h the n a t u r e of the supplementary p r o t e i n s and was t h e r e f o r e not measured. S i n c e the r a t i o n s were f u l l f e d t h i s v a r i a t i o n i n m o i s t u r e c o n t e n t c o u l d not l e a d t o l i m i t i n g f e e d consumption on r a t i o n s c o n t a i n i n g h i g h e r l e v e l s of w a t e r . 12 I n c l u d e d i n T a b l e 6 are the a n a l y t i c a l p r o x i m a t e com-p o s i t i o n of the f i r s t and t h i r d r a t i o n mixes and t h e i r a v e r a g e s . The d i f f e r e n c e s between the computed and the a n a l y t i c a l composi-t i o n was somewhat d i s a p p o i n t i n g and can b e s t be a t t r i b u t e d t o the v a r i a b i l i t y i n t h e supplementary p r o t e i n s o u r c e s . The f a t c o n -t e n t of the whale meat and c h i c k e n waste r a t i o n s , by a c t u a l a n a l -y s i s , a re lower t h a n the a n t i c i p a t e d f a t c o n t e n t s . I t t h e n f o l l o w s t h a t t h e a n a l y t i c a l v a l u e s f o r t h e s e p r o t e i n s o u r c e s as p r e s e n t e d i n T a b l e 5 must have been h i g h e r t h a n t h e a c t u a l a v e r -age c o m p o s i t i o n and as a r e s u l t the mixed r a t i o n s had a lower f a t c o n t e n t . Westock (63) c o n s i d e r e d whale meat f r o m d i f f e r e n t s o u r -ces t o have a f a t percentage f r o m 10-11 and a p r o t e i n p e r c e n t a g e f r o m 77-83» when e x p r e s s e d on a d r y w e i g h t b a s i s . On the b a s i s of the a c t u a l a n a l y s e s the whale meat used f o r the r a t i o n s c o n -t a i n e d 17 per c e n t f a t w h i c h must have been h i g h e r t h a n the a c t u a l average f a t c o n t e n t . I t i s r e g r e t a b l e t h a t t h e s e d i s c r e p a n c i e s o c c u r r e d but as p r e v i o u s l y mentioned t h e s e p r o d u c t s are h i g h l y v a r i a b l e i n c o m p o s i t i o n . T h i s f a c t makes i t v e r y d i f f i c u l t t o ob-t a i n a r e p r e s e n t a t i v e sample f o r a n a l y s i s w h i c h i s t y p i c a l of t h e supplementary p r o t e i n s o u r c e s . The t e r m supplementary p r o t e i n s o u r c e has been used t o d e s c r i b e the a n i m a l p r o t e i n s . The r e a s o n f o r t h i s t e r m becomes apparent when the t o t a l p r o t e i n i n the r a t i o n a r i s i n g f r o m the d i f -f e r e n t s o u r c e s i s examined. Of the t o t a l p r o t e i n i n the r a t i o n V l . 5 per cent was p r o v i d e d by the c e r e a l mix, 1^.5 per c e n t by 1 3 Table 6 Constituent Horse Whale Chicken A Chicken B -Herring Horse Meat 3 7 1 lbs. Whale Meat 2 3 8 lbs. Chicken A 3 5 2 lbs. Chicken B 3 7 6 lbs. Herring 3 2 5 lbs. Liver 9 3 9 3 ' 92 92 92 Bone Meal . 1 3 1*+ 8 Edible Fat 3 V 5 3 5 * 7 Cereal 2 6 1 2 6 1 2 5 7 2 5 9 2 6 0 Water To bring ration to hamburger-! like consistency Computed Proximate Composition: Dry Weight Basis Protein % 3 2 . 9 3 3 . 2 3 2 . 9 3 3 . 0 3 3 . 2 Fat % 2 1 . 0 2 1 . 2 2 1 . 0 2 0 . 9 2 1 . 2 Ash % 6 . 7 6 . 8 6 . 7 6 . 7 6 . 8 Analytical Proximate Composition: Mix 1 -Protein % 3 3 . 7 3 ^ . 9 3 7 . 6 3 9 . 3 3 1 . 7 Fat % 2 3 . 0 1 9 . 2 1 7 . 0 1 3 . 2 2h.l Ash % 6 . 1 6 . 1 7 . 8 7 . 8 6 . 2 Dry Matter % 3 9 . h 3 8 . k 3 6 . 3 3H-.3 3 5 . 8 Analytical Proximate Composition: Mix 3 Protein % 3 6 . 0 3 6 . 8 3 6 . 9 3 5 . 9 3 3 . 6 Fat % 1 9 . 0 1 7 . 2 lh.2 8 . 8 2 1 . 6 Ash % 6 . 3 6 . 6 8 . 0 8 . 0 7 . 3 Dry Matter % 3 8 . 5 if 3 . 0 ^ 2 . 3 kl.O * 3 . 7 Analytical Proximate Composition: Average Mix 1 and 1 Protein % 3H-.8 3 5 . 8 3 7 . 3 3 7 . 6 3 2 . 7 Fat % 2 1 . 0 1 8 . 2 1 5 . 0 1 1 . 0 2 2 . 8 Ash . % 6 . 1 6 . 3 7 . 9 7 . 9 6 . 7 Dry Matter % 3 8 . 9 H - 0 i 7 3 9 . 3 3 7 . 7 3 9 . 8 l i v e r and the remaining per cent by the animal protein source. On t h i s basis, the animal proteins are considered to be supple-mentary since they provided only a f r a c t i o n of the t o t a l pro-t e i n . When the various animal proteins are compared for mainten-ance, reproduction and growth of the mink, they can only be compared on the basis of the i r supplementary value and cannot be compared d i r e c t l y as proteins. If the animal proteins sources were tested i n a semi-purified d i e t where they were the only protein source, then a comparison could be made between proteins. In the present work the animal proteins w i l l be compared on the basis of their supplementary value i n the r a t i o n . Description of the Experimental Rations The formulation of the f i v e basic rations has been described. From each basic r a t i o n four d i s t i n c t rations were de-ri v e d . Two of these were stored as frozen rations and the other two were canned. One of the frozen rations and one of the canned rations had a commercial antioxidant added. In t o t a l , there were 20 d i s t i n c t rations derived from the f i v e basic r a t i o n s . For con-venience each r a t i o n was given a descriptive code. A l l rations when described are referred by t h i s code which i s l i s t e d i n Table 7. For example, r a t i o n HAF-1 i s described as frozen horse meat r a t i o n which contains the antioxidant. 15 HAF-1 HAC-2 HF-3 HC-^ WAF-5 WAC-6 WF-7 WC-8 Table 7  Ration Code CAAF-9 CMC-10 CAF-11 CAC-12 CBAF-13 CBAC-l^ CBF-15 CBC-16 FAF-17 FAC-18 FF-19 FC-20 H- Horse Meat W- Whale Meat CA- Chicken Waste A CB- Chicken Waste B F- Herring A- Antioxidant F- Frozen C- Canned 5. Choice of the Antioxidant for the Experimental Rations There are a variety of antioxidants available for the stabilization of fats in feeding stuffs. The choice of an anti-oxidant for a particular use is contingent upon a knowledge of the oxidative mechanism and the properties of the various anti-oxidants and their combinations. Antioxidants are used extensively in a variety of pro-ducts for the stabilization of fats from the deleterious effects of labile oxygen (6 , 8 , 28, ^l) . Fats, in the presence of labile oxygen undergo oxidation in two well defined phases ( 32 ) . In the f i rs t , or induction phase, there is no apparent evidence of oxi-dation as determinable by organoleptic or other tests for rancidity (19, 30 , 3 1 , ^ 0 , 50 ) . In the second phase, the velocity of the reaction increases rapidly in a logarithmic manner. Once this phase has set in , deterioration of the fat proceeds rapidly and rancidity can easily be detected by organoleptic means ( 32 ) . 16 The length of the induction phase depends upon the amount of natural occurring antioxidants i n i t i a l l y present. It has been shown with pure f a t t y acids that there i s no induction phase. (32) When antioxidants are added to a substance they lengthen the i n i t i a l induction phase to such an extent that there i s no ap-preciable oxidative r a n c i d i t y f o r an extended period. The mechanism of oxidative r a n c i d i t y has been reviewed frequently ( 6 , 8 , 22 , 27 , 30 , 3 2 ) . It has been established that the oxidative process i s a free r a d i c a l reaction. Antioxidants are able to c u r t a i l the formation of free r a d i c a l s and i n so doing become oxidized themselves (hi). Antioxidants are of two general types, aromatic phenols and t h e i r derivatives or aromatic amines and t h e i r d e r i v a t i v e s . Both types are used extensively for the s t a b i l i z a t i o n of f a t s . Of the two general types, the aromatic phenols are more water s o l -uable and are more applicable to a fat-water system. Most antioxidants are used for s t a b i l i z i n g f a t s which may l a t e r be added to other products. Very few antioxidants have been used i n fat-water systems ( 8 , 3 2 ) . Evaluating antioxidants i n such products as meats, f i s h and cereals i s complicated because of the presence of other components such as water and sa l t s which may influence the action of the antioxidant. To date the r e s u l t s of using antioxidants i n meats, f i s h and cereals have been d i s -appointing though some progress has been made i n some cases ( 8 ) . 17 In a r t i f i c a l fat-water systems, c i t r i c acid is an ex-cellent synergist for such primary phenolic antioxidants as propyl gallate and butylated hydroxy-anisole ( 8 ) . Most metals and metal ions are powerful pro-oxidants and synergists owe their activity to their metal scavenging powers. They slow the oxi-dative process by forming chelates with metal ions and thereby, greatly reducing their concentration. The antioxidant chosen for the experimental rations was Tenox VII, manufactured by the Eastman Kodak Company. The com-position of Tenox VII is given in Table 8 . Table 8  Composition of Tenox VII Constituent Per Cent Butylated Hydroxy-Anisole 28 Propyl Gallate 12 C i t r i c Acid • 6 Mixed Glycerides 20 Propylene Glycol 3^ Butylated hydroxy-anisole and propyl gallate are the primary antioxidants and c i t r i c acid is the synergist: . C i t r i c acid, i n the presence of these two antioxidants i s a powerful acid synergist and has been used for a variety of products (28 , 3 0 ) . The fact that c i t r i c acid is water soluble and propyl gallate is slightly water soluble aids in the dispersion of the antioxidant to the fat-water interfaces. Since mink rations might be regarded as a complicated fat-water system, i t was f e l t 18 t h a t w i t h the knowledge at hand, Tenox VII might serve as an adequate a n t i o x i d a n t . The f a c t t h a t i t has been approved f o r human and animal use suggested t h a t i t would be a safe a n t i -oxidant . The manufacturers of Tenox VII recommend i t s use at 0.05 per cent of the f a t content of the r a t i o n . T h i s recommen-d a t i o n i s f o r f a t s added t o a d r y r a t i o n and i t was f e l t t h a t the l e v e l should be i n c r e a s e d t o 0.1 per cent of the f a t content of the r a t i o n s i n c e i t might be d i f f i c u l t t o o b t a i n a u n i f o r m d i s p e r s i o n of the a n t i o x i d a n t i n the wet r a t i o n s . 6 . Mixing, Canning and Storage of the R a t i o n s The r a t i o n s were mixed at the P a c i f i c Fur Breeders Cooperative at New Westminster, B r i t i s h Columbia. E i g h t e e n hours p r i o r t o mixing, the f r o z e n i n g r e d i e n t s were allowed t o thaw. At mixing time they were s t i l l i c e c o l d but workable. The r a t i o n s were blended i n a l a r g e mixing machine normally used f o r mixing commercial mink r a t i o n s . The c e r e a l mix and bonemeal were placed f i r s t i n t o the mixer. With the mixer i n motion, melted f a t was s l o w l y poured over the mixing c e r e a l . The meat i n g r e d i e n t s (supplementary p r o t e i n source and l i v e r ) were passed through a g r i n d e r s i t u a t e d on top of the mixing machine. Water was added at the same time as the meat i n g r e d i e n t s u n t i l the r a t i o n had a hamburger-like c o n s i s t e n c y . The i n g r e d i e n t s l i s t e d f o r one b a s i c r a t i o n (Table 6) were s u f f i c i e n t f o r one mix. The a n t i o x i d a n t had been p r e v i o u s l y i n c o r p o r a t e d i n t o one h a l f of the t o t a l c e r e a l mix. A f t e r mixing, the r a t i o n s were sacked i n 50 pound paper bags and immediately f r o z e n i n the q u i c k f r e e z e . They were then s t o r e d at -10°F. 19 Because of the l a r g e q u a n t i t i e s r e q u i r e d the r a t i o n s were mixed at t h r e e d i f f e r e n t t i m e s . The f i r s t mix was on D e c . 3 1 , 1955s the second mix was on June h, 1956 and the f i n a l mix was on S e p t . 2 1 , 1956. E a c h r a t i o n mix r e q u i r e d about hO man h o u r s . One h a l f of the f r o z e n r a t i o n s (Dec . 31 mix) were t r a n s f e r r e d t o I m p e r i a l Cannery at S t e v e s t o n , B . C . where t h e y were canned . The r a t i o n s were a l l o w e d t o thaw f o r 2h h o u r s , r e -mixed and packed by hand i n t o 20 ounce c a n s . The cans were s e a l e d m e c h a n i c a l l y and r e t o r t e d f o r 2>>- hours a t 2 H - 0 ° F . as r e c o m -mended by the t e c h n i c a l s u p e r v i s o r of the A m e r i c a n Can C o . The remainder of the f r o z e n r a t i o n s were t r a n s f e r r e d to the U n i v e r s i t y where they were s t o r e d at 0 ° F . The canned r a t i o n s were s t o r e d a t the p r e v a i l i n g temperature of the mink sheds . I I I . E x p e r i m e n t a l D e s i g n I t was i n t e n d e d t h a t each of the twenty e x p e r i m e n t a l groups would c o n s i s t of t e n a d u l t female and two male mink. The t e n females were t o c o n s i s t of f i v e s t a n d a r d s , three p a s t e l s and two s i l v e b l u s w i t h males of c o r r e s p o n d i n g c o l o u r phases . I n t h i s way i t was hoped to ach ieve a d i s t r i b u t i o n of the c o l o u r phases which were t y p i c a l of the i n d u s t r y . F o r reasons beyond the c o n -t r o l o f t h i s l a b o r a t o r y i t was not p o s s i b l e t o o b t a i n s u f f i c i e n t an imals t o b r i n g a l l the e x p e r i m e n t a l groups t o the number d e s i r e d . 20 I.V.. Management A l l the mink were vaccinated aginst distemper prior to the experiment. Each female received one-half m l . and each male one ml. of a l i v e virus vaccine. A l l the animals were housed i n the U n i v e r s i t y 1 s experi-mental mink u n i t . It can be considered to by t o p i c a l of ranch conditions. The frozen rations were set out to thaw 2*+ hours prior to feeding. If the rations were too dry, water was added just prior to feeding. The canned rations were fed from a s p e c i a l l y constructed nest box as designed by Mr. C. Harvey, senior animal technician. This permitted a 20 ounce can of feed to be before the mink at a l l times. In general, the females ate a can of feed every three days and the males every two days. No d i f f i c u l t y was experienced i n feeding the mink from the cans and for the most part there was very l i t t l e waste. Animals were weighed at approximately monthly i n t e r v a l s on a scale that was marked i n 20 gm. d i v i s i o n s . The only depar-ture from this weighing schedule occurred during the gestation and pre-weaning period. 21 V. Experimental 1. Maintenance The maintenance requirements of an animal encompasses i t s need for energy and protein for r e s p i r a t i o n , c i r c u l a t i o n of the blood, digestion and other metabolic processes, for the maintenance of body temperature and the repair of worn out tissues without causing an increase or decrease i n weight of the animal ( 2 ) . Nutrients i n excess of the maintenance requirements are used for productive purposes, such as, gaining weight i n the young, development of a foetus or the production of milk and eggs. A r a t i o n may then be said to s a t i s f y the maintenance requirements i f i t maintains the animals weight during a period when the animal i s not engaged i n any productive process. In the mink th i s period covers the winter months. Weight gained or l o s t was used as the c r i t e r i o n for measuring the maintenance perfor-mance of the various r a t i o n s . The maintenance period extended from Jan. 20 to March 21 , 1956 since breeding began on March 15 . The i n i t i a l weights were recorded on Jan. 7 , 1956 and the experimental feeding commenced on Jan. 20 , 1956. The average weights and the net gain or loss for the adult female mink during the maintenance period are given i n Appendix A for a l l the r a t i o n s , except those containing herring. These w i l l be treated i n a l a t e r section. The animals on a l l the r a t i o n s , with one exception (CBAC-i L 0, showed a s l i g h t weight gain. In order to e s t a b l i s h 22 differences between the various treatments, the data were sub-jected to an analysis of variance (16). The average weight gained or l o s t for each r a t i o n group was used as the v a r i a t e . The r e -sults of the analysis for the maintenance period i s given i n Table 9. Table 9 Analysis of Variance for the Maintenance Period Source of Error Sums of D.F. M.S. F. Tabled F Sauares P = . 0 5 Canning (C) 1 78H- .91 10.13 .Antioxidant (A) 32h 1 32H- - .38 10.13 Proteins (P) 2879 3 960 1.11 9.28 Interaction (C.A.) 8*fl 1 8U-1 .98 10.13 Interaction (CP.) 14-13 3 H-71 .55 9.28 Interaction (A.P.) H-788 3 160 ,.19 9.28 Error 2577 3 859 T o t a l 13606 15 Canning refers to the canned rations and the frozen rations (no l e v e l of canning). Antioxidant r e f e r s to the rations with antioxidant and those with no l e v e l of antioxidant. Proteins refer to the rations containing the f i v e supplementary protein sources. From the analysis of variance i t i s apparent that a l l the calculated F values are less than t h e i r corresponding tabled values which indicates that there are no s t a t i s t i c a l differences between 23 any of the t r e a t m e n t s f o r t h e a d u l t female mink d u r i n g t h e main-tenance p e r i o d . A c c o r d i n g t o Brody (11) the maintenance r e q u i r e -ments, i n terms of d i g e s t i b l e n u t r i e n t s are a p p r o x i m a t e l y t w i c e the b a s a l energy r e q u i r e m e n t s , whereas the r e q u i r e m e n t f o r p r o -d u c t i v e purposes are a p p r o x i m a t e l y f i v e t i m e s t h e b a s a l r e q u i r e m e n t . S i n c e the r a t i o n s were d e s i g n e d t o m a i n t a i n a s a t i s f a c t o r y growth r a t e , i t i s t h e r e f o r e not s u r p r i s i n g t o f i n d no d i f f e r e n c e s d u r i n g the maintenance phase of the e x p e r i m e n t . There was no s t a t i s t i c a l d i f f e r e n c e between the f r o z e n and t h e canned r a t i o n s . However, i t was noted t h a t the mink r e -c e i v i n g the f r o z e n r a t i o n s were s l o w l y r e d u c i n g t h e i r f e e d consump-t i o n near t h e end of t h e f i r s t r a t i o n mix (mid d l e of Ha y ) . .Feed consumption i n c r e a s e d when the mink r e c e i v e d t h e f r e s h l y mixed second l o t of f e e d (June 5) . T h i s apparent d e c l i n e i n f e e d consumption of a r a t i o n s t o r e d f o r s e v e r a l months a t a low temper-a t u r e may r e f l e c t t he d e s t r u c t i o n of some n u t r i e n t ( s ) . F o r example, i t i s shown i n a l a t e r s e c t i o n t h a t t h i a m i n e i s d e s t r o y e d t o a c e r t a i n e x t e n t upon p r o l o n g e d s t o r a g e a t 0°F. The h e r r i n g r a t i o n s , as mixed, were u n s a t i s f a c t o r y as a maintenance d i e t f o r the a d u l t female mink. Feed consumption began t o d e c l i n e a f t e r two weeks and by f o u r weeks i t was p r a c -t i c a l l y n i l . The w e i g h t l o s s e s of the h e r r i n g groups are g i v e n i n T a b l e 2 H - , Appendix B. The average weight l o s s of a l l the h e r r i n g r a t i o n s was 115 gm. per f e m a l e . The w e i g h t l o s s on t h e canned r a t i o n s was g r e a t e r t h a n t h a t on t h e f r o z e n r a t i o n s . Feed consumption was i m m e d i a t e l y r e s t o r e d when the mink were supplemented 2h w i t h a 1 per cen t aqueous s o l u t i o n of a complete v i t a m i n mix ( N u t r i t i o n a l B i o c h e m i c a l C o r p o r a t i o n V i t a m i n M i x ) . I n order t o dete r m i n e the l a c k i n g v i t a m i n , t h e mink f r o m the h e r r i n g groups were r e a l l o c a t e d i n t o f o u r groups and r e c e i v e d the f o l l o w i n g v i t a m i n supplements i n t h e i r d r i n k i n g water f r o m March 2 t o March 15 , 1956: Group 1 - T h i a m i n : 2 mg. per day. Group 2 - F o l i c A c i d : 0.18 mg. per day. Group 3 - Thiamine and F o l i c A c i d : l e v e l s of Gp. 1 and 2 . Group M- - One per cent aqueous s o l u t i o n of N.B.C. v i t a m i n mix. Each mink was g i v e n 200 c c . of each s o l u t i o n per day. Two hun-dred c c . of a 1 per cent aqueous N.B.C. v i t a m i n mix s o l u t i o n c o n t a i n e d 2 mg. of t h i a m i n e and 0.18 mg. of f o l i c a c i d . Weight d a t a and f e e d consumption p r i o r t o and a f t e r v i t a m i n s u p p l e m e n t a t i o n are g i v e n i n Ta b l e 25 , Appendix B. S u p p l e m e n t a t i o n w i t h t h i a m i n e and t h i a m i n e p l u s f o l i c a c i d mar-k e d l y i n c r e a s e d the f e e d consumption and the w e i g h t ga i n e d whereas t r e a t m e n t w i t h f o l i c a c i d caused a d e c r e a s e i n w e i g h t , though f e e d consumption was i n c r e a s e d . T h i s l a t t e r i n c r e a s e i n f e e d consumption may have been due t o a c a r r y - o v e r e f f e c t f r om s u p p l e -m e n t a t i o n by t h e complete v i t a m i n mix. The mink r e c e i v i n g the complete v i t a m i n mix a t f i r s t l o s t some weight but t h e n began t o g a i n . T h e i r f e e d consumption was a l s o markedly i n c r e a s e d . From the above, i t was conclu d e d t h a t t h i a m i n e was t h e l i m i t i n g v i t a m i n and a c c o r d i n g l y a l l the mink on t h e f o u r h e r r i n g r a t i o n s r e c e i v e d d a i l y , i n t h e i r d r i n k i n g water 2 mg. of t h i a m i n e h y d r o c h l o r i d e f o r 2 5 the remainder of the e x p e r i m e n t . As e v i d e n c e d i n T a b l e 26, Appendix B, the mink on the h e r r i n g r a t i o n s , w i t h t h i a m i n e sup-p l e m e n t a t i o n , soon i n c r e a s e d t h e i r w e i g h t s above t h e i r i n i t i a l w e i g h t . I t must be remembered t h a t the l a s t w e i g h t shown may be c o m p l i c a t e d by pregnancy. The f a i l u r e of t h e h e r r i n g r a t i o n s w i t h o u t t h i a m i n e s u p p l e m e n t a t i o n may be a t t r i b u t e d t o the enzyme, t h i a m i n a s e , w h i c h has been shown t o be p r e s e n t i n numerous s p e c i e s of f i s h ( 6 0 ) . Thiaminase i s more f r e q u e n t l y found i n t h e f r e s h water f i s h t h a n i n s a l t water f i s h . (66) Thiaminase has been demon-s t r a t e d t o be p r e s e n t i n A t l a n t i c h e r r i n g (53) and P a c i f i c h e r -r i n g (6*+) but not i n B a l t i c h e r r i n g ( 39 ) . The f a i l u r e t o demon-s t r a t e t h i a m i n a s e i n B a l t i c h e r r i n g may be due i n p a r t t o the crude method used f o r d e t e r m i n i n g t h i a m i n e . Gats f e d a d i e t c o n t a i n i n g s a l t w ater h e r r i n g d e v e l o p t y p i c a l t h i a m i n e d e f i c i e n c e s ( 5 ^ ) . Chastek P a r a l y s i s ( a d i s e a s e i n mink and f o x e s r e s u l t i n g f r o m the consumption of f i s h c o n t a i n -i n g t h i a m i n a s e ) has been produced i n mink f e d a d i e t c o n t a i n i n g 19 l b s . P a c i f i c Coast h e r r i n g and 16 l b s . of wheat ( 65 ) . I t has a l s o been produced i n mink f e d a d i e t c o n t a i n i n g 50 per cent of Great Lake's h e r r i n g ( 29 ) . One i n v e s t i g a t o r (26) c o u l d o n l y demonstrate a 20 per c e n t l o s s of t h i a m i n e upon r e f r i g e r a t e d s t o r a g e of Great Lake's h e r r i n g d u r i n g a f i v e week p e r i o d . I n t h i s case the h e r r i n g had been f i l l e t e d p r i o r t o s t o r a g e and s i n c e t h i a m i n a s e i s g e n e r a l l y absent f r o m muscle but c o n c e n t r a t e d i n the v i s c e r e a l organs ( 60 ) , t h e major enzyme c o n t a i n i n g m a t e r i a l 26 would have been removed. Thus, t h e d e s t r u c t i o n of t h i a m i n e would be g r e a t l y reduced i n f i l l e t e d h e r r i n g as compared t o ground h e r r i n g where t h i a m i n a s e i s e v e n l y d i s t r i b u t e d . Thiamine added t o the h e r r i n g r a t i o n s was r a p i d l y de-s t r o y e d . A n a l y s i s of the h e r r i n g r a t i o n s f o r t h i a m i n e f o u r days a f t e r m i x i n g showed t h a t t h e v i t a m i n had been c o m p l e t e l y d e s t r o y e d . No t h i a m i n e was p r e s e n t i n any of the canned r a t i o n s ( T a b l e 1 0 ) . When 9h,5 meg. of t h i a m i n e h y d r o c h l o r i d e , i n t h e f o r m of f o r -t i f i e d r i c e p e l l e t s ,were mixed w i t h 10 gm. of r a t i o n FAF -17 and a l l o w e d t o i n c u b a t e f o r two hours a t room t e m p e r a t u r e , 78.8 per c e n t of the t h i a m i n e was d e s t r o y e d . I t has been shown t h a t d a i l y s u p p l e m e n t a t i o n of t h e d r i n k i n g water w i t h 2 mg. of t h i a m i n e h y d r o c h l o r i d e r e s t o r e d f e e d consumption and growth i n the mink r e c e i v i n g the h e r r i n g r a t i o n s . The d e s t r u c t i o n of thiamine t a k e s p l a c e i n the f e e d and not i n t h e gut f o r i t has been shown t h a t t h i a m i n a s e i s d e s t r o y e d by p e p t i c d i g e s t i o n (55)* The d e s t r u c t i o n of t h i a m i n e by t h i a m i n a s e i s an e n z y m a t i c h y d r o l y s i s y i e l d i n g M—methyl-5-hydroxy m e t h y l e t h y l t h i a z o l e and 2 m e t h y l - H — a m i n o - 5 - h y d r o x y m e t h y l p y r i m i d i n e ( 66 ) . 2 . Adequacy of the Thiamine L e v e l i n a Canned Horsemeat R a t i o n The r e s u l t s of the maintenance experiment i n d i c a t e t h a t a d u l t , female mink f e d canned r a t i o n s w i l l m a i n t a i n t h e i r body w e i g h t . T a b l e 10 compares the average t h i a m i n e c o n t e n t s of t h e f r o z e n and canned r a t i o n s . I t i s e v i d e n t t h a t the t h i a m i n e l e v e l s i n the canned r a t i o n s are much lower t h a n t h e f r o z e n r a t i o n s . 27 T a b l e 10 Average Thiamine Content o f . t h e F r o z e n and Canned B a s i c R a t i o n s Wet B a s i s B a s i c R a t i o n Canned F r o z e n mca/g m. mcg./gm. Horse Meat 0.17 1.05 Whale Meat 0 .25 1.09 C h i c k e n A & B 0 .13 1.10 H e r r i n g 0 .00 0 .00 They are below t h o s e suggested by the N a t i o n a l R e s e a r c h C o u n c i l (^9) w h i c h i s 0 . 3 ^ meg. per gm. of wet r a t i o n ( d r y matter i s 3*+ per c e n t ) . The f o l l o w i n g e x periment was d e s i g n e d t o e s t a b l i s h i f the l e v e l of t h i a m i n e i n a canned r a t i o n (HAC-^f) was s u f f i c i e n t t o m a i n t a i n l a r g e a d u l t mink. A canned h e r r i n g r a t i o n (FC -20 ) was f e d t o c o n f i r m t h e r e s u l t s of the maintenance experiment and t o i n v e s t i g a t e the p o s s i b l e t h i a m i n e r e s e r v e s of a d u l t male mink. E i g h t mature a d u l t male mink (*+ S t a n d a r d s and k Mutants) were f e d a canned horse meat r a t i o n (HAC-1*-) and a n o t h e r s i m i l a r group were f e d a canned h e r r i n g r a t i o n (FC -20 ) f o r a p e r i o d of 11 weeks from May 8 t o J u l y 2*f, 1956. Weekly w e i g h t s and f e e d c o n -sumption were r e c o r d e d . Each mink r e c e i v i n g the h e r r i n g r a t i o n was a l l o w e d t o l o s e 200-300 gm. b e f o r e i t r e c e i v e d a d a i l y s u p p l e -ment of 2 mg. of t h i a m i n e h y d r o c h l o r i d e i n the d r i n k i n g w a t e r . A g r a p h i c r e c o r d of the average w e i g h t and f e e d consump-t i o n f o r the two groups are r e c o r d e d i n F i g . 1 and 2 , Appendix C. 28 The mink r e c e i v i n g the h e r r i n g r a t i o n s s u f f e r e d s l i g h t w e i g h t l o s s e s d u r i n g the f i r s t two weeks but a p r e c i p i t o u s w e i g ht l o s s a f t e r the t h i r d week. The w e i g h t l o s s was a l s o p a r a l l e l e d by a d e c r e a s e i n f e e d consumption. S h o r t l y a f t e r s u p p l e m e n t a t i o n w i t h t h i a m i n e the mink began t o i n c r e a s e t h e i r w e i g h t and f e e d consumption. S i n c e t h e weight l o s s e s were o n l y s l i g h t d u r i n g the f i r s t two weeks i t would appear t h a t the mink had some t h i a -mine r e s e r v e . The s h a r p d e c l i n e i n w e i g h t a f t e r the t h i r d week on a t h i a m i n e d e f i c i e n t d i e t would i n d i c a t e t h a t the r e s e r v e s had been d e p l e t e d . I n g e n e r a l , the group f e d the horse meat r a t i o n had a s l i g h t weight l o s s over the e x p e r i m e n t a l p e r i o d . As e x p e c t e d , f e e d consumption p a r a l l e l e d an i n c r e a s e or d e c r e a s e of body w e i g h t . I t would appear t h a t the mink r e c e i v i n g the canned horse meat were a t t h e i r maintenance r e q u i r e m e n t or s l i g h t l y below. S i n c e f e e d consumption had been r e c o r d e d the d a i l y t h i a m i n e i n t a k e was c a l c u l a t e d . The average d a i l y f e e d consumption per mink was 158 gm. of wet f e e d or 60 gm. of d r y f e e d . The average body w e i g h t was 1390 gm. and thus t h e d a i l y t h i a m i n e i n t a k e per K i l o body we i g h t was .019mg. The N a t i o n a l R e s e a r c h C o u n c i l suggested d a i l y r e q u i r e m e n t f o r t h i a m i n e C+9) i s .001 mg. per gram of d r y m a t t e r . Thus, the suggested r e q u i r e m e n t per K i l o body w e i g h t i s .0V3 mg. T h i s suggested d a i l y r e q u i r e m e n t i s a p p r o x i m a t e l y t w i c e t h e amount the mink r e c e i v e d f r o m the canned horse meat r a t i o n . T h i s would suggest t h a t the N a t i o n a l R e s e a r c h C o u n c i l (**9) recommended l e v e l s 29 a r e t o o h i g h . The p r e s e n t r e s u l t s suggest t h a t a t h i a m i n e l e v e l of a p p r o x i m a t e l y . 0 2 mg. per k i l o body w e i g h t or . 0 0 5 nig. per pound of f e e d as f e d can s u p p l y the maintenance r e q u i r e m e n t s f o r a d u l t male mink. I t i s r e a l i z e d t h a t f u r t h e r work i s r e q u i r e d t o v a l i d a t e t h i s s u g g e s t i o n . Loeschke ( 3 7 ) i s c u r r e n t l y w o r k i n g on t h i s phase of mink n u t r i t i o n . 3 . R e p r o d u c t i o n Each e x p e r i m e n t a l group was t r e a t e d as a b r e e d i n g group of t e n females and two m ales. An attempt was made t o s t a y w i t h i n t h i s group f o r a l l m a t i n g s . Towards th e end of the b r e e d i n g season some males from o t h e r e x p e r i m e n t a l groups had t o be used where a w i t h i n group male f a i l e d t o handle h i s f e m a l e s s a t i s f a c -t o r i l y . The b r e e d i n g p e r i o d extended from March 1 5 t o A p r i l 8 , 1 9 5 6 w i t h the m a j o r i t y of the f e m a l e s b e i n g bred between March 1 5 and March 2 5 . Though the f i r s t k i t s were b o r n on A p r i l 2 2 the m a j o r i t y were b o r n d u r i n g the f i r s t two weeks of May. I t was i n t e n d e d t o wean the male k i t s at ^ 0 0 gm. and the female k i t s a t 3 0 0 gm. A t weaning, the k i t s were a p p r o x i m a t e l y 7 weeks o l d . The r e p r o d u c t i v e and weaning d a t a f o r the e x p e r i m e n t a l groups are g i v e n i n Appendix D. K i t s b o r n per female were used as t h e v a r i a t e i n the a n a l y s i s of v a r i a n c e f o r the r e p r o d u c t i v e phase. The r e s u l t s of the a n a l y s i s a r e p r e s e n t e d i n T a b l e 1 1 . 30 T a b l e 11 A n a l y s i s of V a r i a n c e f o r R e p r o d u c t i o n Source of E r r o r Sums of L\F, M.S. _, T a b l e d F Sauares p =.05 Canning (C) 21.7 1 21.7 20.7 7.71 A n t i o x i d a n t (A) O.if 1 O.lf o.h 7.71 P r o t e i n s (P) 3.8 if 0.95 0.9 6.39 C.A. 1.6 1 1.6 1.5 7.71 C P . 3.8 if 0.95 0.9 6.39 A.P 3.3 h 0.8 0.8 6.39 E r r o r h.2 , h 1.05 T o t a l 38.8 19 ' From th e s e r e s u l t s i t c a n be c o n c l u d e d t h a t t h e r e were no s i g n i f i c a n t d i f f e r e n c e s between t r e a t m e n t s e x c e p t f o r Canning ( C ) . The r e p r o d u c t i v e performance of the mink r e c e i v i n g the canned r a t i o n s was i n f e r i o r t o t h a t of the mink r e c e i v i n g the f r o z e n r a t i o n s a t p = .05. From th e mink on the canned r a t i o n s , 12 k i t s were b o r n from 79 females b r e d , whereas, from t h e mink on t h e f r o z e n r a t i o n s 19H- k i t s were b o r n f r o m 88 f e m a l e s b r e d . The f a i l u r e of the canned r a t i o n s , c a n perhaps be a t t r i -buted t o the d e s t r u c t i o n of some v i t a m i n ( s ) d u r i n g t h e c a n n i n g p r o c e s s . T a b l e 12 p r e s e n t s the V i t a m i n A l e v e l s of the canned r a t i o n s i n I.U. per 100 gm. of r a t i o n . 31 Table 12 Vitamin A levels in the Canned Rations  Rations with Antioxidant Rations without Antioxidant HAC-2 930 I.U./100 gm. HAC-^ h80 I.U./100 gm. WAC-6 2860 WC-8 ,9*0 CMC-10 6^5 CAC-12 785 CBAC-lM- 210 CBC-16 220 FAC-18 2230 FC-20 1250 Ave. 1375 655 The maximum National Research Council requirements (*+9) of Vitamin A are l*+0 I.U. per day. Since a mink w i l l eat about 150 gm. per day i t is apparent that i t w i l l receive sufficient Vitamin A from a l l of the canned rations. It has been shown that the thiamine level in the canned rations is low when compared to the frozen rations (Table 10) and that the thiamine levels in the canned rations are just barely sufficient to meet the maintenance requirement of adult male mink. It is therefore probable that the thiamine levels in the canned rations are not sufficient for reproduction and lactation. There i s also the possibility of Vitamin E being destroyed during the canning process and since one of the primary functions of Vitamin E is to ensure normal reproduction, a reduced level would have a very marked effect. 32 Due t o the complete f a i l u r e i n r e p r o d u c t i o n and due t o d i f f i c u l t i e s i n a r r a n g i n g f o r a d d i t i o n a l c a n n i n g , t h e canned r a t i o n s were d i s c o n t i n u e d f o r t h e remainder of t h e e x p e r i m e n t . The average number of k i t s produced per female bred f rom the f r o z e n r a t i o n s was 2.2. Enders (15) s t a t e s t h a t t h e U n i t e d S t a t e s N a t i o n a l average i n 19H-9 was 3.2 and i n 1950 was 2.8 k i t s per f e m a l e . An average of 3 k i t s per female was c o n s i d e r e d good. From the c i t e d v a l u e s t h e r e p r o d u c t i v e performance of t h e mink on t h e f r o z e n r a t i o n s was below a v e r a g e . The r a t i o n s f e d t o t h e e x p e r i m e n t a l mink were f r o z e n and s t o r e d , a p r a c t i c e w h i c h i s c o n t r a r y t o normal r a n c h c o n d i t i o n s where the r a t i o n s a re mixed d a i l y . Long s t o r a g e p e r i o d s a t f r e e -z i n g t e m p e r a t u r e s r e s u l t i n a g r a d u a l l o s s of n u t r i e n t s t h r o u g h enzymatic and o x i d a t i v e p r o c e s s e s ( 8 ) . I t w i l l be demonstrated i n a l a t e r s e c t i o n t h a t t h e r e i s c o n s i d e r a b l e l o s s o f t h i a m i n e upon pro l o n g e d s t o r a g e a t r e f r i g e r a t e d t e m p e r a t u r e s . I t i s t h e r e -f o r e p r o b a b l e t h a t t h e poor r e p r o d u c t i v e performance of t h e mink r e c e i v i n g the f r o z e n r a t i o n s may have been, i n p a r t , due t o l o s s e s of e s s e n t i a l n u t r i e n t s by s t o r a g e a t r e f r i g e r a t e d t e m p e r a t u r e s . I t had been hoped t h a t the a n t i o x i d a n t would have a f f o r d e d some p r o t e c t i o n but t h e r e was no e v i d e n c e t o suggest t h a t t h i s was the c a s e . Other f a c t o r s such as over a g g r e s s i v e males, s t e r i l e f e m a l e s , f a l s e p r e g n a n c i e s , d i s e a s e , weak sperm, l a c k of o v u l a t i o n and f a t females w i l l a l s o reduce the average l i t t e r s i z e . One 33 s u r v e y o r of r a n c h o p e r a t i o n s (12) found a b r e e d i n g r a t i o of one male t o 3 .5 f e m a l e s as the most s a t i s f a c t o r y r a t i o whereas one male t o 5 f e m a l e s was c o n s i d e r e d b o r d e r l i n e . S i n c e the e x p e r i -m e n t a l groups had one male a s s o c i a t e d w i t h 6 f e m a l e s t h i s may have been another c o n t r i b u t i n g f a c t o r t o the lower t h a n e x p e c t e d f e c u n d i t y . The f a c t t h a t t h e s e mink were hand l e d as e x p e r i m e n t a l a n i m a l s may have i n f l u e n c e d t h e i r r e p r o d u c t i v e performance. S i n c e no s e l e c t i o n p r e s s u r e i n the d i r e c t i o n of i n c r e a s e d f e r t i l i t y has been p o s s i b l e i n t h e U n i v e r s i t y U n i t t o t h i s t i m e , t h i s may a l s o have been a c o n t r i b u t i n g f a c t o r . The average g e s t a t i o n p e r i o d f o r a l l t h e mink was 5 3 . ^ -^ . 0 days w i t h a range of Lf6-61+ d a y s . The average g e s t a t i o n p e r i o d as c o m p i l e d by Enders (15) i s a p p r o x i m a t e l y 51 d a y s . Ranges f r o m 37 t o 91 days have been r e p o r t e d though t h e n o r m a l range i s f r o m k7 t o 75 days. The g e s t a t i o n p e r i o d of the mink on t h e e x p e r i m e n t a l r a t i o n s i s c o n s i d e r e d n o r m a l . k, Gr owth Female mink, w i t h a s s o c i a t e d males f o r b r e e d i n g , have been m a i n t a i n e d s u c c e s s f u l l y on the v a r i o u s e x p e r i m e n t a l r a t i o n s . However, the r e p r o d u c t i v e performance of the mink r e c e i v i n g the canned r a t i o n s was e s s e n t i a l l y a complete f a i l u r e and t h e number of k i t s a v a i l a b l e f r om t h e mink f e d the f r o z e n r a t i o n s was below a v e r a g e . As a r e s u l t , the number of k i t s a v a i l a b l e f o r the growth phase was g r e a t l y reduced f r o m what had been a n t i c i p a t e d a t t h e o u t s e t of the e x p e r i m e n t . I t had been hoped t o have a t l e a s t 10 3* male and 10 female k i t s f o r each e x p e r i m e n t a l r a t i o n . Because of the reduced numbers a v a i l a b l e , 6 male and 6 female k i t s c o n s t i t u t e d an e x p e r i m e n t a l group f o r the t e n d i f f e r e n t f r o z e n r a t i o n s . As e x p l a i n e d p r e v i o u s l y , the canned r a t i o n s were not i n c l u d e d i n the growth phase of t h e e x p e r i m e n t . A l l t h e k i t s were weaned i n the p e r i o d f r o m June 28 t o J u l y 6 , 1956 w i t h t h e m a j o r i t y b e i n g weaned between June 28 and J u l y 3 j 1956. They were f e d the r e s p e c t i v e e x p e r i m e n t a l r a t i o n s u n t i l Nov. 1 1 , 1956. I t had been hoped t o wean the male k i t s a t H O O gm. and the female k i t s a t 300 gm. but because of a d e l a y i n the c o n s t r u c t i o n of n e s t - b o x e s the average weaning w e i g h t s were somewhat h i g h e r t h a n p l a n n e d . Where p o s s i b l e , 6 male and 6 female k i t s were p l a c e d on the same r a t i o n t h e i r mothers had r e c e i v e d but where t h i s was not p o s s i b l e , because of i n s u f f i c i e n t numbers, t h e y were chosen f r o m a r a t i o n t h a t had the same supplementary p r o t e i n s o u r c e . The mink were weighed a t a p p r o x i m a t e l y monthly i n t e r v a l s over t h e e x p e r i m e n t a l p e r i o d i n o r d e r t o r e c o r d t h e i r p r o g r e s s . The average w e i g h t s of the r a t i o n groups and the average w e i g h t ga i n e d f rom weaning t o m a t u r i t y f o r each group are p r e s e n t e d i n Table 27 , Appendix E. The average w e i g h t g a i n e d f o r each group between wean-i n g and m a t u r i t y was used as the v a r i a t e i n t h e a n a l y s i s of v a r i a n c e of t h e growth phase. The r e s u l t s of t h i s a n a l y s i s are p r e s e n t e d i n T a b l e 13 . 35 Table H Source of Error Sums of D.F. M.S, Tabled F. Sauares p = .0? p = .< Sex (S) l , 5 8 l , t f 6 9 1 1,581,^69 705. 7.7 21.2 Antioxidants (A) 2*f,221 1 2*f ,221 10.8 7.7 21.2 Proteins (P) 200,561 if 50,l*f0 22 . i* 6.k 16.0 S.A. 805 1 805 o.k 7.7 21.2 S.P. 65,713 h 16,^-28 7.3 6.h 16.0 A.P 2 5 , W 6,369 2.8 6 . V 16.0 Error 8,967 2,2^2 T o t a l 1,907,215 19 The r e s u l t s of the analysis indicate several differences between treatments. There i s a s i g n i f i c a n t difference at p = .01 between the average gains of the males and the females which of course i s expected. There i s a s i g n i f i c a n t difference at p = .05 but not at p = .01 between the rations containing the antioxidant and those that do not contain i t . The i n c l u s i o n of the antioxidant i n the rations has depressed growth. There are s i g n i f i c a n t d i f -ferences between the supplementary protein sources at p = . 0 1 . The i n t e r a c t i o n between Sex and Proteins i s s i g n i f i c a n t at p = . 0 5 . The differences within the groups composing the source of error i n Table 13 are determined i n the following manner. The analysis of variance has shown a s i g n i f i c a n t difference between sex and antioxidants. Since there are only two sexes and two l e v e l s 36 of a n t i o x i d a n t the t o t a l g a i n s may be d i r e c t l y compared and t h e one w i t h the l a r g e r t o t a l g a i n i s s u p e r i o r t o t h e o t h e r . When t h i s was done, i t was e s t a b l i s h e d t h a t the males ga i n e d more t h a n the f e males ( s i g n i f i c a n t a t p = .01) and t h a t t h e a n t i o x i d a n t d e p r e s s e d growth ( s i g n i f i c a n t a t p = . 0 5 ) . The a n a l y s i s of v a r i a n c e i n d i c a t e s t h a t t h e r e are d i f -f e r e n c e s of g a i n a s s o c i a t e d w i t h the v a r i o u s s u p p l e m e n t a r y p r o t e i n s o u r c e s . The s i g n i f i c a n c e between the g a i n s of t h e mink r e c e i v -i n g t h e v a r i o u s supplementary p r o t e i n s may be d e t e r m i n e d by c a l -c u l a t i n g the minimum d i f f e r e n c e between any two v a r i a t e means r e q u i r e d f o r s i g n i f i c a n c e (M.S.D.). These c a l c u l a t i o n s appear i n Appendix F and f r o m them the f o l l o w i n g c o n c l u s i o n s may be drawn. There i s no s i g n i f i c a n t d i f f e r e n c e a t p = .01 between the Horse Meat, Whale Meat and C h i c k e n Waste A r a t i o n s but t h e s e r a t i o n s as a group are s i g n i f i c a n t l y d i f f e r e n t and s u p e r i o r t o t h e C h i c k e n Waste B and the H e r r i n g r a t i o n s . The a n a l y s i s of v a r i a n c e f o r t h e growth phase a l s o i n d i -c a t e s a s i g n i f i c a n t i n t e r a c t i o n between Sex and P r o t e i n s a t p = . 0 5 . The minimum s i g n i f i c a n c e f o r a d i f f e r e n c e (M.S.D.) f o r t h i s i n t e r -a c t i o n i s c a l c u l a t e d i n Appendix F. From t h e s e c a l c u l a t i o n s T a b l e lh was prepared t o f a c i l i t a t e the i n t e r p r e t a t i o n of the i n t e r a c t i o n between Sex and P r o t e i n s . 37 T a b l e Ih Comparison of the D i f f e r e n c e s i n G a i n due t o the  I n t e r a c t i o n Sex and P r o t e i n s  S i g n i f i c a n c e a t p = .05 w i t h R a t i o n - S e x Horse Whale C h i c k e n C h i c k e n Meat Meat Waste A Waste B H e r r i n g Horse Meat-Females none l e s s none none none Horse Meat-Males none g r e a t e r g r e a t e r g r e a t e r g r e a t e r Whale Meat-Females g r e a t e r none none g r e a t e r g r e a t e r Whale Meat-Males l e s s none none g r e a t e r g r e a t e r C h i c k e n A-Females none none none none g r e a t e r C h i c k e n A-Males l e s s none none g r e a t e r g r e a t e r C h i c k e n B-Females none . l e s s none none none C h i c k e n B-Males l e s s l e s s l e s s none none H e r r i n g - F e m a l e s none l e s s l e s s none none H e r r i n g - M a l e s l e s s l e s s l e s s none none I n t h i s t a b l e , t h e t o t a l gaiis of the males and fe m a l e s f o r each supplementary p r o t e i n source a re compared f o r s i g n i f i c a n c e a t p t o t h e males and f e m a l e s of t h e o t h e r s u p p l e m e n t a r y p r o t e i n sour c e s . The f o l l o w i n g example e x p l a i n s the t e r m i n o l o g y used i n Ta b l e lk. When the C h i c k e n A-Males a r e compared t o t h e males on the o t h e r supplementary p r o t e i n s o u r c e s , the t a b l e i s r e a d as f o l l o w s . The t o t a l g a i n made by the males r e c e i v i n g the C h i c k e n A r a t i o n s was s i g n i f i c a n t l y l e s s ( l e s s ) t h a n t h e t o t a l g a i n made by the males r e c e i v i n g the Horse Meat r a t i o n s , s i g n i f i c a n t l y g r e a t e r t h a n the t o t a l g a i n of t h e males r e c e i v i n g t h e C h i c k e n B and H e r r i n g r a t i o n s but not s i g n i f i c a n t f r o m the g a i n (none) mad by the males r e c e i v i n g t he Whale r a t i o n s . 38 I n g e n e r a l , t h e i n t e r a c t i o n between sex and p r o t e i n s i n d i c a t e s a p a r a l l e l i s m between the supplementary p r o t e i n s o u r c e s but t h e s e d i f f e r e n c e s are g r e a t e r i n the males t h a n i n the f e m a l e s . I t would be a n t i c i p a t e d t h a t d i f f e r e n c e s i n the males would be g r e a t e r t h a n i n t h e f e m a l e s s i n c e a t any g i v e n time a f t e r b i r t h the female i s p h y s i o l o g i c a l l y o l d e r t h a n t h e male ( 1 1 ) . I n o t h e r words, under the c o n d i t i o n s of the p r e s e n t e x p e r i m e n t , f e -males a t weaning had completed 37 .5 per cent of t h e i r f i n a l w e i g h t w h i l e t h e males had completed o n l y 27 per c e n t . The r e s u l t s of t h e a n a l y s i s of v a r i a n c e f o r the growth phase has i n d i c a t e d s i g n i f i c a n t d i f f e r e n c e s between the g a i n s of the groups r e c e i v i n g the d i f f e r e n t s u p p l e m e n t a r y p r o t e i n s o u r c e s . I n a l l p r o b a b i l i t y the d i f f e r e n c e s i n the growth r a t e s of t h e mink on the v a r i o u s e x p e r i m e n t a l r a t i o n s may be s i m i l a r t o t h e d i f f e r e n c e s e n c ountered i n m i n k - f e d v a r i o u s r a n c h d i e t s . These v a r i a t i o n s i n growth r a t e s would occur s i n c e t h e r a t i o n s f e d t o r a n c h mink u n d o u b t e d l y v a r y i n n u t r i t i v e v a l u e and as a r e s u l t d i f f e r e n c e s i n growth r a t e s would o c c u r . I f t h e average growth c u r v e s of each of the e x p e r i m e n t a l r a t i o n s are p l o t t e d , t h e n the spread i n w e i g h t s a t any g i v e n time may be an i n d i c a t i o n of t h e v a r i a t i o n i n w e i g h t s t h a t might be e x p e c t e d i n r a n c h mink. These we i g h t c u r v e s , one f o r the f e m a l e s , F i g . 3 , Appendix E and one f o r the males, F i g . Appendix E, were p l o t t e d f r o m the d a t a p r e s e n t e d i n T a b l e 27 . These c u r v e s show the magnitude i n the spread of w e i g h t a t any time a f t e r weaning. As t h e a n i m a l s grow 39 o l d e r and the d i f f e r e n c e s between r a t i o n s becomes more a p p a r e n t the spread i n w e i g h t s become p r o g r e s s i v e l y l a r g e r . I n the case of the r a n c h mink i t i s d i f f i c u l t t o s e g r e g a t e n u t r i t i o n a l e f f e c t s f r o m i n h e r e n t d i f f e r e n c e s i n t h e mature w e i g h t of the v a r i o u s s t r a i n s . Such d i s t i n c t d i f f e r e n c e s a r e r e c o g n i z e d i n g e o g r a p h i c s t r a i n s of w i l d mink. U n d o u b t e d l y , man has i n c r e a s e d the v a r -i a t i o n i n s i z e of r a n c h mink i n t h e c o u r s e of h i s s e l e c t i o n p r e s -s u r e s f o r c o l o u r phase and p e l t q u a l i t y . I t i s t h e r e f o r e f e l t t h a t t h e s e c u r v e s r e p r e s e n t the v a r i a t i o n i n w e i g h t t h a t might be ex p e c t e d f r o m r a n c h mink w h i c h are f e d d i e t s d i f f e r i n g i n n u t r i -t i v e v a l u e and a r i s i n g f r om t h e v a r i o u s s t r a i n s . The r a t i o n s c o n t a i n i n g Horse Meat, Whale Meat and C h i c k e n Waste A are s u p e r i o r t o those c o n t a i n i n g C h i c k e n Waste B and H e r r i n g . Gunn (17) has compared Whale Meat and Horse Meat i n d i e t s f o r growing mink and found no d i f f e r e n c e i n the t o t a l w e i g h t g a i n e d from weaning t o m a t u r i t y . The p r e s e n t e x p e r i m e n t a l r e s u l t s a l s o i n d i c a t e no d i f f e r e n c e and suggest t h a t Whale Meat may be s u b s t i t u t e d f o r Horse Meat on a d r y weight b a s i s . The s i g n i f i c a n t d i f f e r e n c e between the two C h i c k e n Waste r a t i o n s i s d i f f i c u l t t o e x p l a i n . The two t y p e s of C h i c k e n V/astes d i f f e r i n one r e s p e c t , C h i c k e n Waste A c o n t a i n s the g a l l b l a d d e r and the a n a l p o r t i o n whereas C h i c k e n Waste B does n o t . The r e -s u l t s of the Net P r o t e i n U t i l i z a t i o n V a l u e s of t h e supp l e m e n t a r y p r o t e i n s o u r c e s ( T a b l e 19) show t h a t C h i c k e n Waste A has a h i g h e r v a l u e t h a n C h i c k e n Waste B w h i c h i n d i c a t e s t h a t the p r o t e i n of t h e ho l a t t e r i s i n f e r i o r t o the f o r m e r . I n a l l p r o b a b i l i t y t h e d i f f e r -ence i n the Net P r o t e i n U t i l i z a t i o n V a l u e s of the C h i c k e n Wastes a r o s e f r o m the i n h e r e n t v a r i a b i l i t y i n the c o m p o s i t i o n of t h i s p r o d u c t . When compared t o t h e o t h e r r a t i o n g r o u p s , t h e g a i n s of the H e r r i n g group were l e s s but i t was c e r t a i n l y not due t o p r o -t e i n of i n f e r i o r q u a l i t y . The r e s u l t s of the Net P r o t e i n U t i l i -z a t i o n experiment ( T a b l e 19) show t h a t H e r r i n g has the h i g h e s t v a l u e , even h i g h e r t h a n c a s e i n . R o b e r t s o n (52) has a l s o o b t a i n e d s i m i l a r r e s u l t s on co m m e r c i a l h e r r i n g meals. The poorer p e r f o r m -ance of the H e r r i n g r a t i o n s might be due t o an i n s u f f i c i e n t s u p p l y of t h i a m i n e though t h i s seems r a t h e r u n l i k e l y s i n c e t h e y were b e i n g supplemented d a i l y or i t might be due t o the f o r m a t i o n of r a n c i d i t y i n the r a t i o n s i n c e h e r r i n g f a t i s e a s i l y o x i d i z e d . The growth d e p r e s s a n t e f f e c t of t h e a n t i o x i d a n t , Tenox V I I , would seem t o i n d i c a t e t h a t i t p o s s e s s e s some degree of t o x i c i t y . The a n t i o x i d a n t had been added a t do u b l e t h e recommended l e v e l f o r i t was f e l t t h a t the d i s p e r s i o n of t h e a n t i o x i d a n t i n a wet r a t i o n might be poor. The l e v e l a l l o w e d f o r the a d d i t i o n of an a n t i o x i d a n t t o f a t s c o n t a i n i n g a m i x t u r e of b u t y l a t e d -h y d r o x y - a n i s o l e , p r o p y l g a l l a t e and c i t r i c a c i d (components of Tenox V I I ' a r e : b u t y l a t e d h y d r o x y - a n i s o l e , . 02$ ; p r o p y l g a l l a t e , .01$ ; and c i t r i c a c i d , .005$ ( 8 ) . The l e v e l of Tenox V I I added t o t h e r a t i o n s was .01% of t h e f a t c o n t e n t . From t h e c o m p o s i t i o n of Tenox V I I ( T a b l e 8 ) , the computed p e r c e n t a g e s of the component a n t i o x i d a n t s added t o the f a t of the r a t i o n were b u t y l a t e d h y d r o x y - a n i s o l e , .028$; p r o p y l g a l l a t e , .012$ and c i t r i c a c i d , .006$. A l l of t h e s e were added a t l e v e l s s l i g h t l y h i g h e r t h a n recommended f o r use i n s t a b i l i z i n g f a t s . The above v a l u e s r e f e r t o the a n t i o x i d a n t s as p e r c e n t a g e s .' of t h e f a t c o n t e n t of the r a t i o n and not of t h e t o t a l r a t i o n . A h i g h f a t d i e t w i l l c o n t a i n more a n t i o x i d a n t t h a n a low f a t d i e t i f t he percentage of a n t i o x i d a n t i s based on t h e f a t c o n t e n t . I f an a n i m a l consumes a d i e t c o n t a i n i n g 20 per c e n t f a t i t w i l l not r e c e i v e t w i c e as much a n t i o x i d a n t as i f i t were consuming a d i e t c o n t a i n i n g 10 per cen t f a t s i n c e the f o o d consumption i s l e s s on t h e h i g h f a t d i e t t h a n the low f a t d i e t . Some c a u t i o n t h e n has t o be used i n e v a l u a t i n g d a t a p e r t i n e n t t o the t o x i c i t y of a n t i o x i d a n t s . When a d i e t c o n t a i n i n g 10 per cen t f a t and 0.3 per c e n t b u t y l a t e d h y d r o x y - a n i s o l e was f e d t o r a t s t h e r e was a d e p r e s s i o n of growth ( 2 0 ) . Growth was a l s o d e p r e s s e d i n r a t s by f e e d i n g a d i e t w h i c h c o n t a i n e d 1.17 per cen t p r o p y l g a l l a t e , though o t h e r e x p e r i m e n t s showed t h a t as much as 5 per c e n t was r e q u i r e d ( 3 * 0 . There were no d e l e t e r i o u s e f f e c t s on the performance of g u i n e a p i g s or dogs f e d a d i e t c o n t a i n i n g 0.011 per c e n t p r o p y l g a l l a t e ( 3 ^ ) . I t i s apparent t h a t t h e l e v e l s o f b u t y l a t e d h y d r o x y -a n i s o l e and p r o p y l g a l l a t e w h i c h cause a growth d e p r e s s i o n i n t h e r a t a re h i g h e r t h a n t h o s e c a u s i n g a s i m i l a r d e p r e s s i o n i n t h e mink. The problem of t o x i c i t y of a n t i o x i d a n t s f o r the mink r e q u i r e s f u r -t h e r s t u d y i n or d e r t o e s t a b l i s h s a f e l e v e l s . h2 5 . Fur Q u a l i t y No q u a n t i t a t i v e c o m p a r i s o n of f u r q u a l i t y was made on the mink r e c e i v i n g the e x p e r i m e n t a l r a t i o n s . A t p r e s e n t , the number of mink a t the U n i v e r s i t y i s r e l a t i v e l y s m a l l and i n order t o ensure s u f f i c i e n t numbers f o r f u t u r e e x p e r i m e n t s none of t h e fem a l e s and o n l y **1 f r o m a p o s s i b l e % males were p e l t e d . I n g e n e r a l , the r e t a i n e d mink were of a s u p e r i o r q u a l i t y t o t h o s e p e l t e d s i n c e a s e l e c t i o n p r e s s u r e was e x e r t e d i n f a v o u r of s i z e and p e l t q u a l i t y . The p e l t s were s c o r e d by an a r b i t r a r y system where a v a l u e of 1 was a p e l t of s u p e r i o r q u a l i t y and a v a l u e of 5 was i n f e r i o r . On t h i s system, the average s c o r e of a l l the p e l t s was 2.2 w h i c h i n d i c a t e s a p e l t q u a l i t y s l i g h t l y above the average . From the s m a l l number of e x p e r i m e n t a l a n i m a l s p e l t e d , no q u a n t i t a t i v e c o m p a r i s o n of f u r q u a l i t y c o u l d be made though t h e r e i s an i n d i c a t i o n t h a t f u r q u a l i t y c o u l d be c o n s i d e r e d as ave r a g e . 6. The D e s t r u c t i o n of Thiamine i n t h e E x p e r i m e n t a l R a t i o n s (a) I n t r o d u c t i o n S t u d i e s concerned w i t h the d e s t r u c t i o n of v i t a m i n s d u r -i n g the v a r i o u s p r o c e s s i n g and s t o r a g e s t a g e s of a f e e d p r o d u c t are Important i n t h e f i n a l e v a l u a t i o n of i t s n u t r i t i o n a l adequacy. I n t h i s r e g a r d , the d e s t r u c t i o n of t h i a m i n e i s p a r t i c u l a r l y im-p o r t a n t s i n c e one of the f i r s t s i g n s of a t h i a m i n e d e f i c i e n c y i s a n o r e x i a . When f e e d consumption i s dec r e a s e d by a l i m i t i n g s u p p l y o f t h i a m i n e , o t h e r v i t a m i n s and n u t r i e n t s may t h e n t o o become l i m i t i n g . *3 L o s s e s of v i t a m i n s i n modern p r o c e s s i n g and s t o r a g e are p r i m a r i l y due t o enzymes, c h e m i c a l o x i d a t i o n and e x t r a c t i o n (H-3). The most prominent changes i n a n i m a l , f i s h and d a i r y p r o d u c t s s t o r e d f o r p r o l o n g e d p e r i o d s a t r e f r i g e r a t e d t e m p e r a t u r e s a r e due t o o x i d a t i v e r a n c i d i t y ( 8 , H-3). Mapson (H-3), i n a r e v i e w , i n d i c a t e d t h a t t h e r e was l i t t l e change i n the v i t a m i n s of the B groups when t h e y were s t o r e d a t r e f r i g e r a t e d t e m p e r a t u r e s . However, L e h r e r (36) r e p o r t e d a H-0 per c e n t l o s s of t h i a m i n e i n pork chops s t o r e d a t 0°F. f o r 6 months whereas Lee (33) r e p o r t e d no l o s s of t h i a m i n e i n pork chops s t o r e d a t 0°F. f o r 6 months. L e h r e r (35) a l s o r e p o r t e d a 50 per cen t l o s s o f t h i a m i n e i n lamb chops s t o r e d f o r 6 months at 0°F. L i v e r s l i c e s s t o r e d f o r 2 months a t r e f r i g e r a t e d temper-a t u r e s l o s t 27 per cent of t h e i r t h i a m i n e . The ap p a r e n t c o n f l i c t of p u b l i s h e d r e s u l t s on the d e s t r u c t i o n o f t h i a m i n e upon p r o l o n g e d r e f r i g e r a t e d s t o r a g e may be e x p l a i n e d i n p a r t by the method and type of wrapping used f o r the s t o r e d p r o d u c t . Lee (33) demon-s t r a t e d no t h i a m i n e l o s s i n pork chops wrapped i n 300 MSAT c e l l o -phane and b u t c h e r s paper. T h i s type of wr a p p i n g i s vapour p r o o f and t h e r e f o r e does not a l l o w any a t m o s p h e r i c oxygen t o come i n c o n t a c t w i t h the meat s u r f a c e and presumably g r e a t l y r e d u c e s any o x i d a t i v e r a n c i d i t y . Other wrappings w h i c h are not vapour p r o o f or w h i c h are used c a r e l e s s l y would a l l o w a c c e s s of oxygen t o t h e meat s u r f a c e and hence encourage o x i d a t i o n . F u r t h e r e v i d e n c e t h a t t h i a m i n e i s d e s t r o y e d by o x i -d a t i o n has been demonstrated w i t h d i s t i l l e d water s o l u t i o n s of t h i a m i n e w h i c h were s t o r e d i n s e a l e d ampoules f o r a y e a r . T h i a -mine l o s s was 59 per c e n t but no l o s s o c c u r r e d when the ampoules c o n t a i n e d an atmosphere of n i t r o g e n (13). A d d i t i o n of a n t i o x i d a n t s t o t h e t h i a m i n e s o l u t i o n s d e c r e a s e d t h e t h i a m i n e l o s s and i t was con c l u d e d t h a t oxygen was the d e s t r u c t i v e f a c t o r . I t has a l s o been demonstrated t h a t t h e r e i s a marked i n s t a b i l i t y of t h i a m i n e i n c e r t a i n p u r i f i e d d i e t s (62). An un-s a t u r a t e d o i l , such as l i n s e e d o i l , was more d e l e t e r i o u s t h a n a hydrogenated v e g e t a b l e o i l and t h e a d d i t i o n of a s c o r b i c a c i d or hydroquinnone, s e r v i n g as a n t i o x i d a n t s , i n c r e a s e d t h e s t a b i l i t y of t h i a m i n e (22). T h i s a g a i n i s e v i d e n c e f o r a n o x i d a t i v e de-s t r u c t i o n of t h i a m i n e . However, i n c e r t a i n t y p e s of s a l t m i x t u r e s i t has been demonstrated t h a t d i p o t a s s i u m phosphate i s c h i e f l y r e s p o n s i b l e f o r t h e d e s t r u c t i o n of t h i a m i n e because i t i s v e r y h y g r o s c o p i c and upon h y d r o l y s i s i s a l k a l i n e , p r o v i d i n g c o n d i t i o n s i n w h i c h t h i a m i n e i s v e r y u n s t a b l e (62). Two s e p a r a t e s t u d i e s were made on the d e s t r u c t i o n of t h i a m i n e i n the e x p e r i m e n t a l f r o z e n r a t i o n s i n o r d e r t o e s t a b l i s h i f t he l o s s of t h i a m i n e p r i o r t o e a t i n g would be g r e a t enough t o make t h i a m i n e a l i m i t i n g f a c t o r i n t h e r a t i o n s . I n one s t u d y , the d e s t r u c t i o n of t h i a m i n e was measured over a f o u r month s t o r a g e p e r i o d a t 0°F. w h i l e i n the o t h e r , the d e s t r u c t i o n of t h i a m i n e was measured from the time the f r o z e n r a t i o n s were b e g i n n i n g t o thaw * 5 u n t i l t h e y were consumed by t h e mink. These s t u d i e s were a l s o d e s i g n e d t o show the q u a n t i t a t i v e l o s s of t h i a m i n e upon s t o r a g e and t h e e f f e c t of the a n t i o x i d a n t upon t h i a m i n e d e s t r u c t i o n . (b) The E f f e c t of P r o l o n g e d S t o r a g e a t 0°F. on the Thiamine Content of t h e E x p e r i m e n t a l F r o z e n R a t i o n s . D u p l i c a t e t h i a m i n e d e t e r m i n a t i o n s were made on samples f r o m each of the e x p e r i m e n t a l f r o z e n r a t i o n s a t ©, 33» 77 > and 110 days of s t o r a g e a t 0°F. d u r i n g t h e p e r i o d f r o m June 6 t o S e p t . 2 H - , 1956. The thiochrome procedure as recommended by t h e A s s o c -i a t i o n of V i t a m i n C h e m i s t s , I n c . was used f o r the d e t e r m i n a t i o n of t h i a m i n e (1*+). The m o d i f i c a t i o n s of the procedure and the s a m p l i n g methods are p r e s e n t e d i n Appendix G. D u p l i c a t e r e s u l t s , e x p r e s s e d as meg. of t h i a m i n e per gram of d r y r a t i o n , a r e p r e s e n t e d i n Table 1 5 . The average per c e n t d e s t r u c t i o n of t h i a m i n e f o r a l l the r a t i o n s over the 110 day p e r i o d of s t o r a g e was 2 9 . 2 . The average per c e n t d e s t r u c t i o n of t h i a m i n e i n the r a t i o n s c o n t a i n i n g the a n t i o x i d a n t was 30.2 where-as the average per c e n t d e s t r u c t i o n of t h i a m i n e i n the r a t i o n s c o n t a i n i n g no a n t i o x i d a n t was 2 8 . 2 . There i s t h e n no e v i d e n c e t o suggest t h a t t h e a n t i o x i d a n t e x e r t e d any p r o t e c t i v e e f f e c t upon the d e s t r u c t i o n of t h i a m i n e . The apparent f a i l u r e of t h e a n t i o x i d a n t t o a f f o r d p r o t e c t i o n may be due t o the f a c t t h a t c i t r i c a c i d i s the o n l y water s o l u b l e component of the a n t i o x i d a n t mix-t u r e . S i n c e the c o n c e n t r a t i o n of c i t r i c a c i d i n Tenox V I I i s o n l y h6 6 per c e n t , the r e s u l t i n g c o n c e n t r a t i o n of i t i n the water phase would be v e r y low and f o r t h i s r e a s o n may have been i n s u f f i c i e n t t o p e r m i t t h e d e s t r u c t i o n of t h i a m i n e , e s p e c i a l l y i f t h e r e were some i n t e r f e r e n c e by the food components. The H e r r i n g r a t i o n s c o n t a i n e d no t h i a m i n e s i n c e i t p r o b a b l y was d e s t r o y e d d u r i n g m i x i n g by t h e enzyme, t h i a m i n a s e . A t the time of the f i r s t a n a l y s i s , t h e r a t i o n s were o n l y seven days o l d . (c ) . The D e s t r u c t i o n of Thiamine Between Thawing and  F e e d i n g . A l l t h e e x p e r i m e n t a l r a t i o n s f e d t o the mink a t t h i s t i me were f r o z e n and r e q u i r e d t h a w i n g p r i o r t o f e e d i n g . The thaw-i n g p r o c e s s , a t room t e m p e r a t u r e , t o o k about 2h hours a f t e r w h i c h the r a t i o n s were remixed by hand t o ensure u n i f o r m i t y . I f t h e mink were g i v e n an exce s s of f e e d , the r a t i o n s c o u l d c o n c e i v a b l y r e m a i n on t h e w i r e 2h hours a f t e r t h a w i n g . Thus, the maximum time t h e r a t i o n s had t o d e t e r i o r a t e between t h a w i n g and consump-t i o n was *+8 h o u r s . I n o r d e r t o d e t e r m i n e the t h i a m i n e l o s s be-tween thawing and e a t i n g , samples from each r a t i o n were a n a l y s e d f o r t h i a m i n e a t 2h- hour i n t e r v a l s f o r a t h r e e day p e r i o d . The h e r r i n g r a t i o n s were e x c l u d e d f r o m the s t u d y s i n c e t h e y c o n t a i n e d no t h i a m i n e . T a b l e 16 shows the d e s t r u c t i o n of t h i a m i n e i n the e x p e r i m e n t a l r a t i o n s between t h a w i n g and e a t i n g at 2h hour i n t e r -v a l s . The per c e n t t h i a m i n e d e s t r u c t i o n f o r each r a t i o n i s a l s o g i v e n . *7 T a b l e 15 Thiamine L e v e l s 1 of the E x p e r i m e n t a l R a t i o n s D u r i n g R e f r i g e r a t e d S t o r a g e R a t i o n s June 6 J u l y 9 Aug. 22 S e p t . 2k Per Cent D e s t r u c t i o n HAF -1 H-.7 k.k 3.1 2.9 38.3 k.7 k.5 3.3 2 .9 HF -3 5.9 k.6 3.5 3 .5 if 1.6 5.9 k.6 3 .5 3.k WAF-5 3.9 3.1 H-.3 3.6 7.7 3.9 3 .0 H-.3 3.6 WF-7 5.7 k.Q k.k i f . l 28.7 5.8 h.8 k.k i f . l CAAF -9 6.8 5.2 5.3 3.9 i f2.6 6.7 5.2 5.3 3.8 CAF -11 5.6 5.8 6 .2 H-.9 13.3 5.7 6.1 6.2 k.9 CBAF -13 5.5 5.2 k.Q 3.6 3 2 . i f 5.3 5.2 i f . 8 3.7 CBF -15 5.3 k.7 * . 3 3.8 29 . k 5.6 5.1 i f . i f 3.9 FAF - 17 0.0 0 .0 0 .0 0 .0 0 .0 0 .0 FF - 1 9 0.0 0 .0 0 .0 0 .0 0 .0 0 .0 1 E x p r e s s e d as meg. t h i a m i n e per gm. of d r y r a t i o n . 1*8 T a b l e 16 The D e s t r u c t i o n of Thiamine Between Thawing and F e e d i n g R a t i o n 0 h r s . 2h h r s . ^8 h r s . Per Cent D e s t r u c t i o n H&F-l \ . 8 h.2 h.O 16.7 HF -3 h.Q h.5 • h.2 11.1 WAF-5 k.2 h.O 3.7 12 .5 WF-7 5.3 5.0 h.2 20.0 CAAF -9 h.Q h.2 3.5 27.8 C A F - l l 5.6 5.3 5.0 9.8 CBAF -13 k.O 3.5 3.2 20.0 CBF -15 5.0 5.0 k.5 i o . 5 2 Micrograms t h i a m i n e per gm. of d r y r a t i o n . The average per c e n t d e s t r u c t i o n of t h i a m i n e f o r a l l the r a t i o n s was 1 6 . 0 ; the average per cent d e s t r u c t i o n of t h i a -mine i n the r a t i o n s c o n t a i n i n g the a n t i o x i d a n t was 19.3 and the average per cent d e s t r u c t i o n of t h i a m i n e i n the r a t i o n s c o n t a i n -i n g no a n t i o x i d a n t was 1 2 . 8 . There was no e v i d e n c e of any p r o -t e c t i o n of t h i a m i n e by the a n t i o x i d a n t . Though the r a t i o n s c o n t a i n i n g the a n t i o x i d a n t had a l a r g e r t h i a m i n e d e s t r u c t i o n t h a n the r a t i o n s c o n t a i n i n g no a n t i o x i d a n t , the d i f f e r e n c e was not s i g n i f i c a n t . The average t h i a m i n e l o s s f o r a l l t h e r a t i o n s s t o r e d a t 0°F. f o r a f o u r month p e r i o d was 28.8 per c e n t and t h e average t h i a m i n e l o s s f o r a l l the r a t i o n s between t h a w i n g and consumption 9^ was 16.0 per c e n t . A c c o r d i n g l y , the average l o s s , c a l c u l a t e d from the i n i t i a l th iamine c o n t e n t , due t o a maximum s torage p e r i o d and the p e r i o d between thawing and consumpt ion would be h0.2 per cent of the i n i t i a l l e v e l . The lowest i n i t i a l t h i a m i n e l e v e l was 3.9 meg. per gram of d r y r a t i o n (Tab le 15). The maximum average th iamine d e s t r u c -t i o n was *f0.2 per cent and presumably 2.3 meg. of th iamine per gram of d r y r a t i o n would be l e f t f o r the mink. I f an average f eed consumption of 60 grams of d r y matter per day i s assumed f o r a d u l t f e m a l e s , t h e n they would consume at a minimum, O.lh mg. of th iamine per d a y . The upper l e v e l of th iamine recommended by the N a t i o n a l R e s e a r c h C o u n c i l (^ 9) i s 0.1 mg. per d a y . T h i s , t h e n suggests t h a t the th iamine l e v e l s i n the r a t i o n s even a f t e r f o u r months of r e f r i g e r a t e d s torage are adequate f o r the mink . I t i s t h e r e f o r e suggested t h a t t h i a m i n e should not have become the l i m i t i n g n u t r i e n t f a c t o r i n the f r o z e n r a t i o n s . The r e s u l t s of the s t u d i e s on the d e s t r u c t i o n of t h i a -mine i n the e x p e r i m e n t a l r a t i o n s i n d i c a t e t h a t the a n t i o x i d a n t had no b e n e f i c i a l e f f e c t i n p r e v e n t i n g the ^des t ruc t ion of t h i a -mine . I n v e s t i g a t i o n s (13, 22) have shown t h a t the d e s t r u c t i o n of th iamine can be o x i d a t i v e and t h a t the amount of th iamine d e s t r o y e d can be decreased by the e x c l u s i o n of oxygen or the a d d i t i o n of an a n t i o x i d a n t . The a p p l i c a t i o n of a n t i o x i d a n t s t o f r e s h meats , f i s h and p o u l t r y has not g e n e r a l l y proved s a t i s f a c t o r y (8) and there are cases of success (28, ^1) and f a i l u r e (5, 18). 50 Perhaps the i n e f f e c t i v e n e s s of the a n t i o x i d a n t i n p r e v e n t i n g the d e s t r u c t i o n of t h i a m i n e may he due t o the d i f f i c u l t y of d i s p e r s i n g the a n t i o x i d a n t or t o t h e low water s o l u b i l i t y of the components of Tenox V I I i n the r a t i o n m i x t u r e . The i n f l u e n c e of foo d com-ponents may have r e n d e r e d the a n t i o x i d a n t i n e f f e c t i v e ( 8 ) . 7. D i g e s t i b i l i t y S t u d i e s on the E x p e r i m e n t a l R a t i o n s The term per ce n t d i g e s t i b i l i t y as a p p l i e d t o a f e e d -s t u f f r e f e r s t o t h a t percentage of t h e f e e d s t u f f w h i c h i s ab-sorbed from the s m a l l i n t e s t i n e (¥+). The u s u a l method i s t o measure the t o t a l f e e d consumed and f a e c e s v o i d e d over a d e f i n i t e time i n t e r v a l . The r a t i o of the f e e d absorbed ( t o t a l f e e d c o n -sumed l e s s the f a e c a l l o s s ) t o the f e e d consumed, e x p r e s s e d as a percentage i s t a k e n t o be the per cent d i g e s t i b i l i t y . T h i s t e r m s h o u l d be d i s t i n g u i s h e d from t r u e d i g e s t i b i l i t y w h i c h t a k e s i n t o c o n s i d e r a t i o n the m e t a b o l i c p o r t i o n of the f a e c a l o u t p u t , l a r g e l y a r i s i n g f r o m g a s t r o i n t e s t i n a l s e c r e t i o n s , c e l l s of the i n t e s t i n a l mucosa and i n t e s t i n a l m i c r o f l o r a (1). The c o l l e c t i o n method f o r d e t e r m i n i n g the per c e n t d i -g e s t i b i l i t y of a n u t r i e n t i n v o l v e s the measurement of the t o t a l i n t a k e of the n u t r i e n t and the t o t a l f a e c a l output over a p r e -determined time i n t e r v a l . T h i s method i s l a b o u r i o u s and i n most i n s t a n c e s r e q u i r e s s p e c i a l a p p a r a t u s . A s i m p l e r and l e s s time consuming method based on the use of c e r t a i n exogenous or i n d o -genous i n d i c a t o r s has been proposed (M+). The i n d i c a t o r may be a s i m p l e c h e m i c a l compound such as chromic o x i d e w h i c h i s 51 i n d i g e s t i b l e and n o n - a b s o r b a b l e . I n a d d i t i o n , i t must be non-t o x i c t o the a n i m a l and pass t h r o u g h the d i g e s t i v e t r a c t a t a u n i f o r m r a t e . The i n d i c a t o r i s mixed u n i f o r m l y w i t h the f e e d at a low l e v e l and f e d t o the a n i m a l . A f t e r a c e r t a i n time i n t e r v a l the f e e d and f a e c e s a r e a n a l y s e d f o r the i n d i c a t o r . From the c o n c e n t r a t i o n of the i n d i c a t o r i n the f e e d and f a e c e s the per cent d i g e s t i b i l i t y may be c a l c u l a t e d . The d i g e s t i b i l i t y of a s p e c i f i c n u t r i e n t , such as n i t r o g e n , may a l s o be d e t e r m i n e d f r o m the r a t i o of the c o n c e n t r a t i o n of the i n d i c a t o r t o t h a t of n i t r o g e n i n the f e e d and the same r a t i o i n the f a e c e s r e s u l t i n g f r o m the f e e d (M+). There have been few p u b l i s h e d s t u d i e s concerned w i t h the d i g e s t i b i l i t i e s of mink r a t i o n s and s p e c i f i c n u t r i e n t s i n t h e s e r a t i o n s . I t w i l l be shown t h a t the f e e d consumption of the mink r e c e i v i n g the d i f f e r e n t r a t i o n s v a r i e d m a r k e d l y ( T a b l e 2 0 ) . F o r example, the mink r e c e i v i n g the C h i c k e n Waste r a t i o n s ate more t h a n the mink r e c e i v i n g the Horse or Whale Meat r a t i o n s . These d i f f e r e n c e s i n f e e d consumption may p o s s i b l y a r i s e f r om d i f f e r e n c e s i n d i g e s t i b i l i t y . T h i s s t u d y was t h e n i n i t i a t e d t o e s t a b l i s h the d i g e s t i b i l i t y c o e f f i c i e n t s of the v a r i o u s r a t i o n s i n o r d e r t o attempt t o e x p l a i n the d i f f e r e n c e s i n f e e d consumption. A c c o r d i n g l y , the f o l l o w i n g d i g e s t i b i l i t y s t u d i e s were i n i t i a t e d . T o t a l d i g e s t i b i l i t y , n i t r o g e n d i g e s t i b i l i t y and f a t d i g e s t i b i l i t y were de t e r m i n e d f o r each of the 10 e x p e r i m e n t a l f r o z e n r a t i o n s , u s i n g chromic o x i d e as t h e i n d i c a t o r . I n a d d i t i o n 52 " c a r b o h y d r a t e " d i g e s t i b i l i t y was c a l c u l a t e d by assuming t h a t the m i n e r a l c o n t e n t of the r a t i o n was n o n - d i g e s t i b l e . The d e t a i l s of t h e methods and t h e i n d i v i d u a l c a l c u l a t i o n s f o r the f i f t y a d u l t female mink are g i v e n i n Ap p e n d i x H. The average t o t a l d i g e s t i b i l i t y , n i t r o g e n d i g e s t i b i l i t y , f a t d i g e s t i b i l i t y and " c a r b o h y d r a t e " d i g e s t i b i l i t y w i t h t h e i r s t a n d a r d d e v i a t i o n s a re p r e s e n t e d i n Ta b l e 17. T a b l e 17 Per Cent T o t a l . N i t r o g e n . F a t and " C a r b o h y d r a t e " D i g e s t i b i l i t i e s of t he F r o z e n E x p e r i m e n t a l R a t i o n s R a t i o n T o t a l N i t r o g e n F a t " C a r b o h y d r a t e " No. D i g e s t i b i l i t y D i g e s t i b i l i t y D i g e s t i b i l i t y D i g e s t i b i l i t y HAF -1 6h.5 + 5.9 73.8 + 6.6 91 .5 + 1.8 27.0 + k.7 HF -3 7 1 . k + 6.1+ 77.7 + 8.0 9H-.5 + 1.1 27.3 + k.k WAF-5 63.5 + 1.7 75.0 + 6.8 87.2 + 2.3 27.5 + 3.3 WF-7 60.0 + k.9 71.2 + 8.3 8 3 . ^ + 1.8 27.5 + 3.5 CAAF -9 61.0 + 6.3 69.3 + 8.9 81+.3 + 2.6 30.3 + »f.8 €AF - 1 1 60.9 + 5.1 68.8 + 2.8 87.9 + 1.8 30.6 + ^ . 3 CBAF -13 62.h + 2.7 68.1 + 5.3 Qk.O + 1.9 31.6 + 1.8 CBF -15 58.2 + 3.3 69.6 + 5.3 87.8 + 1.7 22.3 + 2.0 FAF - 17 52.2 + 5.3 60.0 + 9.7 86 . h + 1.7 22.5 + k.7 FF - 1 9 60.6 + 9.7 72.0 + 7 .5 91.5 + 1.8 22.7 + 5*5 Average 61.5 + 5.1 70.6 + 6.9 87.9 + 1.9 26.9 k.o 53 The " t " t e s t (16) was used t o t e s t t h e s i g n i f i c a n c e be-tween the r a t i o n s a t p = . 0 5 . When t h e r a t i o n s were compared w i t h r e s p e c t t o t o t a l d i g e s t i b i l i t y , t h e r e was a s i g n i f i c a n t d i f -f e r e n c e between r a t i o n HF -3 and FAF - 17 but t h e d i f f e r e n c e s between the o t h e r r a t i o n s were not s i g n i f i c a n t . There were no s i g n i f i c a n t d i f f e r e n c e s between the r a t i o n s when the n i t r o g e n d i g e s t i b i l i t i e s were compared. However, when the f a t d i g e s t i b i l i t i e s were com-pared the f o l l o w i n g r a t i o n s were s i g n i f i c a n t l y d i f f e r e n t w i t h one another a t p - . 0 5 . HAF -1 w i t h WF-7 and CBAF - 13 ; HF -3 w i t h WAF -5 , WF -7 , CAAF - 9 , CAF - 1 1 , CBAF - 13 , CBF -15 and FAF - 1 7 ; FF - 1 9 w i t h WF -7 , CAAF - 9 , CBAF-13 and FAF - 1 7 . O n l y CBAF -13 was s i g n i f i c a n t l y d i f -f e r e n t from CBF -15 when the " c a r b o h y d r a t e " d i g e s t i b i l i t i e s were compared. I n g e n e r a l , t o t a l d i g e s t i b i l i t y , n i t r o g e n d i g e s t i b i l i t y and " c a r b o h y d r a t e " d i g e s t i b i l i t y were s i m i l a r f o r a l l the r a t i o n s e x c e p t f o r the few s i g n i f i c a n t d i f f e r e n c e s . The d i f f e r e n c e s i n f a t d i g e s t i b i l i t y between the r a t i o n s was g r e a t e r and i n g e n e r a l b o t h horse meat r a t i o n s and t h e one h e r r i n g r a t i o n (FAF -19 ) had h i g h e r f a t d i g e s t i b i l i t i e s t h a n the o t h e r s . I t would be err o n e o u s t o c o n c l u d e t h a t h orse f a t i s more e a s i l y d i g e s t e d t h a n the o t h e r f a t s s i n c e the f a t i n any one r a t i o n i s a composite m i x t u r e of the f a t d e r i v e d f rom the supplementary p r o t e i n s o u r c e , t h e c e r e a l mix and any added f a t . T a b l e 18 r e l a t e s the per c e n t of t h e f a t d e r i v e d f rom the r a t i o n components. I t i s apparent from t h e h i g h d i g e s t i b i l i t y and t h e v a r i e t y of the s o u r c e s of f a t t h a t mink, i n 5^ g e n e r a l , have the a b i l i t y t o u t i l i z e f a t s w i t h g r e a t f a c i l i t y and by so d o i n g , the f a t p o r t i o n of the d i e t can p r o v i d e t h e major p o r t i o n of the energy r e q u i r e d f o r maintenance. T a b l e 18 P e r Cent of the F a t D e r i v e d f r o m the R a t i o n Components R a t i o n s Component Horse Whale C h i c k e n A C h i c k e n B H e r r i n g Horse Meat 36.5 Whale Meat .7 C h i c k e n A 59.0 C h i c k e n B 55.0 H e r r i n g 27.1 L i v e r 7.2 8.3 9.9 13 .5 6 .5 Added F a t 3 39.8 71.9 8 .2 51.1 C e r e a l 16.5 19 . 1 22.9 31 .5 15.3 100.0$ 100.0$ 100.0$ 100.0$ 100.0$ 3 Devon Deep F r y F a t There a re many f a c t o r s i n f l u e n c i n g d i g e s t i b i l i t y c o e f -f i c i e n t s w h i c h make comparisons d i f f i c u l t between i n v e s t i g a t i o n s (M+). Crude f i b r e t e n d s t o lower t h e d i g e s t i b i l i t y of a l l nu-t r i e n t s . A s h o r t time of passage of f e e d t e n ds t o lower the apparent d i g e s t i b i l i t y of a l l n u t r i e n t s . I n t h i s r e s p e c t , t h e time of passage of the mink i s e x t r e m e l y s h o r t and ranges f r o m 55 lg- t o 2^- hours C+2) and c o n s e q u e n t l y d i g e s t i b i l i t y c o e f f i c i e n t s would t e n d t o be r e d u c e d . Worthen (65) f e d a r a t i o n t o mink w h i c h c o n t a i n e d 19 p a r t s of h e r r i n g t o 16 p a r t s of wheat and found t h e average t o t a l d i g e s t i b i l i t y t o be 52.7 per c e n t and the average n i t r o g e n d i g e s -t i b i l i t y t o be 83.7 per c e n t . Madramootoo (U-2) used two d i f f e r e n t c e r e a l r a t i o n s and found the t o t a l d i g e s t i b i l i t y t o be 52.1 and 60.2 per c e n t . The average t o t a l d i g e s t i b i l i t y of t h e p r e s e n t e x p e r i m e n t a l r a t i o n s was 6 l . 5 per c e n t w h i c h was h i g h e r t h a n the v a l u e s c i t e d by the above w o r k e r s . T h i s i s p r o b a b l y due t o t h e f a c t t h a t t h e i r r a t i o n s c o n t a i n e d v e r y h i g h l e v e l s of c e r e a l and c o n s e q u e n t l y were l e s s d i g e s t i b l e . B e r n a r d (7) found t h a t the p r o t e i n d i g e s t i b i l i t y ranged f r o m 83.6 t o 90.6 per cent and t h e f a t d i g e s t i b i l i t y v a r i e d f r o m Qk.O t o 97.9 per cen t when mink were f e d d i e t s c o n t a i n i n g 75 per ce n t horse meat. McCay (H-5) c i t e s t h a t t h e p r o t e i n d i g e s t e d by f o x e s on v a r i o u s d i e t s ranged f r o m 71 t o 91 per c e n t . I n dogs, about 80 per cent of the p r o t e i n i s d i g e s t e d i n a mixed f e e d . I n a s e r i e s of 19 d i g e s t i b i l i t y t r i a l s , t o t a l d i g e s t i b i l i t y v a r i e d f r o m 53 t o Qk per c e n t ; p r o t e i n d i g e s t i b i l i t y v a r i e d f r o m 51 t o 80 per cent and f a t d i g e s t i b i l i t y v a r i e d f r o m 66 t o 9k per c e n t . I t i s e v i d e n t f r o m t h e d i g e s t i b i l i t y c o e f f i c i e n t s c i t e d f o r the mink, f o x and the dog t h a t t h e r e i s g r e a t v a r i a b i l i t y i n th e s e c o e f f i c i e n t s w i t h i n t h e same s p e c i e s . These d i f f e r e n c e s a r e m a i n l y due t o v a r i a b i l i t y i n r a t i o n c o m p o s i t i o n . When t h e average d i g e s t i b i l i t i e s of t h e e x p e r i m e n t a l r a t i o n s , as p r e s e n t e d i n Ta b l e 17, are compared t o those c i t e d f o r the mink, dog and the f o x , the agreement i s good e x c e p t f o r t h e n i t r o g e n d i g e s t i b i l i t y w h i c h seems t o be somewhat l o w e r . P e r -haps the d i f f i c u l t y i n u t i l i z i n g p l a n t p r o t e i n s would l e a d t o t h i s r e l a t i v e l y low n i t r o g e n d i g e s t i b i l i t y . The low " c a r b o h y d r a t e " d i g e s t i b i l i t y s u g g e s t s t h a t t h e mink has d i f f i c u l t y i n u t i l i z i n g " c a r b o h y d r a t e s " and i n p a r t i c -u l a r , t h e c e r e a l p o r t i o n of the r a t i o n . Dry d i e t s f o r mink w h i c h c o n t a i n h i g h p e r c e n t a g e s of c e r e a l have not proved s u c c e s s f u l f o r r a i s i n g c o m m e r c i a l mink. The main d i f f i c u l t y , a c c o r d i n g t o K i f e r and h i s a s s o c i a t e s (83 , 86) i s t h a t such r a t i o n s a re r e l a t i v e l y i n d i g e s t i b l e . A l b e r t a r a n c h e r s (63*) c l a i m t h a t c o o k i n g r a t i o n s , w h i c h c o n t a i n a h i g h percentage of c e r e a l , p e r m i t s adequate growth of c o m m e r c i a l mink. They c l a i m t h a t c o o k i n g t h e c e r e a l makes i t more d i g e s t i b l e . However, B e r n a r d (7)» i n a s t u d y of the d i g e s -t i b i l i t y of s t a r c h f r om v a r i o u s c e r e a l s f e d t o mink, found t h a t c o o k i n g i n c r e a s e s the u t i l i z a t i o n of c o r n s t a r c h and c o r n but d i d not i n c r e a s e the d i g e s t i b i l i t y of s t a r c h from wheat and o a t s . I t i s apparent t h a t the problem of t h e u t i l i z a t i o n of c e r e a l s by mink r e q u i r e s f u r t h e r c a r e f u l s t u d y . Because of the r e l a t i v e l y low d i g e s t i b i l i t y of c e r e a l s , a n attempt i s b e i n g made i n t h i s l a b o r a t o r y , t o i n c r e a s e t h e i r u t i l i z a t i o n by the use of c e r t a i n c a r b o h y d r a s e s . 57 8. The Net P r o t e i n U t i l i z a t i o n of the Supplementary P r o t e i n  Sources The p r i m a r y f u n c t i o n of d i e t a r y p r o t e i n i s t o f u r n i s h a m i x t u r e of amino a c i d s of the proper p a t t e r n f o r the s y n t h e s i s of t i s s u e p r o t e i n s (1). The t h e o r e t i c a l minimum r e q u i r e m e n t of p r o t e i n i s the amount a c t u a l l y s t o r e d by t h e body p l u s the endo-genous l o s s e s . The a c t u a l d i e t a r y r e q u i r e m e n t must be much h i g h e r t o p r o v i d e f o r d i g e s t i v e l o s s e s and t h e b i o l o g i c a l v a l u e of t h e p r o t e i n . D i g e s t i b i l i t y c o e f f i c i e n t s t a k e i n t o a c c o u n t the l o s s e s due t o i n c o m p l e t e d i g e s t i o n of the d i e t a r y p r o t e i n . The b i o -l o g i c a l v a l u e of a p r o t e i n a s s e s s e s the e f f i c i e n c y w i t h w h i c h the absorbed amino a c i d s a r e u t i l i z e d i n f o r m i n g body p r o t e i n . I t r e p r e s e n t s the percentage of absorbed p r o t e i n t h a t i s s t o r e d by the body. The term net p r o t e i n u t i l i z a t i o n or sometimes r e -f e r r e d t o as net p r o t e i n v a l u e embodies b o t h t h e d i g e s t i b i l i t y and b i o l o g i c a l v a l u e of a d i e t a r y p r o t e i n i n t h a t i t r e p r e s e n t s the percentage of the i n g e s t e d p r o t e i n t h a t i s s t o r e d i n the body. The net p r o t e i n v a l u e (N.P.U.) i s t h e n the p r o d u c t of t h e b i o -l o g i c a l v a l u e (B.V.) and the d i g e s t i b i l i t y (D.) of t h e p r o t e i n . B i o l o g i c a l v a l u e measurements on p r o t e i n s have r e c e i v e d c o n s i d e r a b l e a t t e n t i o n because the d i g e s t i b i l i t y of a p r o t e i n f o r a s p e c i e s on a p a r t i c u l a r r a t i o n tends t o be r e l a t i v e l y c o n s t a n t f o r each c l a s s of p r o t e i n s and i n s o f a r as i s known the d i g e s -t i b i l i t y of a p r o t e i n i s not r e l a t e d t o i t s amino a c i d c o m p o s i t i o n (56). The b i o l o g i c v a l u e i s a d i r e c t measure of the amino a c i d c o m p o s i t i o n . 58 There are numerous methods f o r measuring b i o l o g i c a l v a l u e and t h e s e have been r e v i e w e d r e c e n t l y ( 1 , 56) but the b a s i s of c o mparison f o r a l l methods i s the w e l l e s t a b l i s h e d Thomas-M i t c h e l l procedure (M+). T h i s procedure i s t e d i o u s and time c o n -suming i n t h a t i t r e q u i r e s numerous n i t r o g e n d e t e r m i n a t i o n s be-f o r e a v a l u e i s o b t a i n e d . R e c e n t l y M i l l e r and Bender (H-7) have proposed a much sho r t e n e d method f o r measuring n e t p r o t e i n u t i l i z a t i o n . T h e i r method compares f a v o u r a b l y t o t h e T h o m a s - M i t c h e l l p r o c e d u r e . The advantage of t h i s method over th e c l a s s i c one l i e s i n the s m a l l number of measurements made over a s h o r t e x p e r i m e n t a l p e r i o d . F o r example, the e v a l u a t i o n of 3 p r o t e i n s by the T h o m a s - M i t c h e l l method w i t h 12 r a t s i n v o l v e s 120 n i t r o g e n e s t i m a t i o n s of the u r i n e and f a e c e s as w e l l as 3 f o o d a n a l y s e s and 60 measurements of f o o d consumption over a p e r i o d of 6 weeks. The M i l l e r and Bender (H-7) method can e v a l u a t e 7 p r o t e i n s , u s i n g 32 r a t s , 8 f e e d consumption measurements i n a p e r i o d of 10 days and n i t r o g e n de-t e r m i n a t i o n s on t h e f e e d . The M l l e r and Bender method (H-7) c o n s i s t s e s s e n t i a l l y of measuring the net n i t r o g e n s t o r e d i n a t e s t group of r a t s over a 7-10 day p e r i o d f o r w h i c h the t o t a l n i t r o g e n i n t a k e i s measured. The net n i t r o g e n s t o r e d of the t e s t group i s the d i f f e r e n c e be-tween the t o t a l body n i t r o g e n of the t e s t group and t h a t of a c o n -t r o l group f e d a n i t r o g e n f r e e d i e t . A c o r r e c t i o n i s made f o r the c o n t r o l group i f t h e n i t r o g e n f r e e d i e t c o n t a i n s t r a c e s of 59 n i t r o g e n . Body n i t r o g e n i s de termined from the body water c o n -t e n t of the r a t s s i n c e M i l l e r and Bender (*+•?) have shown a h i g h c o r r e l a t i o n between body n i t r o g e n and body w a t e r . The net p r o t e i n u t i l i z a t i o n (N.P .U.) i s c a l c u l a t e d by a p p l y i n g the f o l l o w i n g e q u a t i o n : N.P .U. = B - ( B k - I k) I where B and B k are t o t a l body n i t r o g e n of the t e s t group and n o n -p r o t e i n group r e s p e c t i v e l y , and I and I k are the n i t r o g e n i n t a k e of these two g r o u p s . One of the o b j e c t i v e s of t h i s exper iment was t o t e s t the supplementary v a l u e of the v a r i o u s t e s t p r o t e i n s w i t h r e s p e c t to maintenance , r e p r o d u c t i o n and growth i n the mink. S i n c e the t e s t p r o t e i n s o n l y made up per cent of the t o t a l p r o t e i n i n the r a t i o n s , i t i s d i f f i c u l t t o a r r i v e at any t r u e assessment of the amino a c i d complement s u p p l i e d by the supplementary p r o -t e i n s because of the a s s o c i a t e d p r o t e i n from the l i v e r and c e r e a l p o r t i o n of the r a t i o n . The net p r o t e i n u t i l i z a t i o n v a l u e s of the f i v e supplementary p r o t e i n sources were measured by the M i l l e r and Bender method C+7) i n order t o a r r i v e at an assessment of the amino a c i d s s u p p l i e d by these p r o t e i n s . The net p r o t e i n v a l u e s of the f i v e supplementary p r o t e i n sources were measured on the r a t and i t may be argued t h a t the v a l u e s o b t a i n e d may not be a p p l i c a b l e t o the mink. G e n e r a l l y , v a l u e s f o r the b i o l o g i c a l e s t i m a t i o n of p r o t e i n s i n the r a t are a p p l i c a b l e t o other s p e c i e s 60 i f the p r o t e i n s are compared over t h e same p h y s i o l o g i c a l age p e r i o d . The use of the mink as the t e s t a n i m a l would, of c o u r s e , be f a r t o o c o s t l y . The net p r o t e i n u t i l i z a t i o n v a l u e s (N.P.U.) f o r the f i v e s upplementary p r o t e i n s o u r c e s and c a s e i n as a c o n t r o l , as determined by the M i l l e r and Bender method (k6) are presented i n T a b l e 19 . The d e t a i l s of the method and the c a l c u l a t i o n are g i v e n i n Appendix I . T a b l e 19 Net P r o t e i n U t i l i z a t i o n V a l u e s of the Supplementary P r o t e i n s Supplementary P r o t e i n N.P.U. Horse Meat . . 5 ^ Whale Meat . 5 ^ C h i c k e n Waste A A 3 C h i c k e n Waste B .33 H e r r i n g .65 C a s e i n .61 C a s e i n (72) .60 The above v a l u e s f o r t h e n e t p r o t e i n u t i l i z a t i o n of the supplementary p r o t e i n s o u r c e s i n d i c a t e t h a t whole h e r r i n g was the s u p e r i o r p r o t e i n f o r t h e r a t , even more f a v o u r a b l e t h a n c a s e i n . Horse meat and whale meat are i d e n t i c a l but much lo w e r t h a n h e r r i n g ; t h e c h i c k e n wastes A and B are t h e l o w e s t . B o t h horse meat and whale meat are e s s e n t i a l l y muscle t i s s u e and 61 s i n c e t h e amino a c i d c o m p o s i t i o n of muscle of a l l s p e c i e s i s s i m i l a r (56) i t would be expected t h a t the v a l u e s f o r horse meat and whale meat s h o u l d be a l i k e . I f t h e muscle of h e r r i n g were used as the p r o t e i n source i n s t e a d of whole h e r r i n g , the net p r o t e i n u t i l i z a t i o n would s t i l l be h i g h e r because th e presence of bone and s k i n r educes the d i g e s t i b i l i t y . B o t h the c h i c k e n wastes are low as would be e x p e c t e d because of the r e l a t i v e l y l a r g e amount of heads and f e e t p r e s e n t . These f i b r o u s t y p e s of p r o t e i n s are p o o r l y u t i l i z e d by most s p e c i e s . I t i s d i f f i c u l t t o e x p l a i n the d i f f e r e n c e between the v a l u e s f o r the two t y p e s of c h i c k e n wastes w h i c h o n l y d i f f e r f r o m one another i n t h a t C h i c k e n A does not have the g a l l b l a d d e r and a n a l p o r t i o n removed whereas C h i c k e n B d o e s . The d i f f e r e n c e i n t h e s e v a l u e s can b e s t be e x p l a i n e d on the b a s i s of t h e v a r i -a b i l i t y of c o m p o s i t i o n s i n c e t h e c h i c k e n waste used i n the e x p e r -iment was o b t a i n e d f r o m d i f f e r e n t s o u r c e s and a t d i f f e r e n t t i m e s of the y e a r . 9 . The R e l a t i o n s h i p Between Maintenance Feed Consumption  and Body Weight i n A d u l t Mink Mink are n o r m a l l y f e d a wet r a t i o n w h i c h has a hamburger-l i k e c o n s i s t e n c y . The normal p r a c t i c e i s t o f e e d t h e r a t i o n on t o p of the w i r e cage and l e t t h e mink p u l l a t the r a t i o n w i t h i t s t e e t h . The mink o f t e n p u l l s more t h a n i t can e a t i n one b i t e and i n v a r i a b l y some of the r a t i o n d r ops t h r o u g h the w i r e bottom of the cage onto the ground. Some mink pack t h e i r f e e d i n t o the n e s t box where t h e y w i l l o f t e n l e a v e some on t h e bottom of the box. 62 I f the mink i s g i v e n an excess of f e e d , some w i l l be l e f t on t h e w i r e t o d r y and harden. I t i s d i f f i c u l t t o remove q u a n t i t a t i v e l y u n l e s s the mink i s t a k e n f rom the cage. P r a c t i c a l o b s e r v a t i o n s over an extended p e r i o d suggests t h a t the f e e d l o s s f r o m t h e s e v a r i o u s causes may be from 10-25 per cent of the f e e d o f f e r e d . A c c u r a t e f e e d consumption d a t a f o r the mink a r e e x t r e m e l y d i f f i -c u l t t o o b t a i n u n l e s s time consuming t e c h n i q u e s a r e employed. I f such t e c h n i q u e s are used one i s s e v e r e l y l i m i t e d i n the number of a n i m a l s t h a t c a n be s t u d i e d a t any one t i m e . S i n c e one h a l f of the r a t i o n s used f o r t h e maintenance experiment were canned, t h e r e was an o p p o r t u n i t y t o r e c o r d f e e d consumption w i t h some degree of a c c u r a c y . I t was soon observed t h a t the mink a t e u n i f o r m l y i n t o the canned f e e d and t h a t t h e r e was l i t t l e or no wastage. The d a i l y f e e d consumption c o u l d e a s i l y be r e c o r d e d by d a i l y w e i g h i n g of the f e e d c a n s . D a i l y f e e d consumption f o r a l l t h e a d u l t mink (82 mink) on the canned r a t i o n s , w i t h the e x c e p t i o n of those mink r e c e i v i n g t h e canned h e r r i n g r a t i o n s , were r e c o r d e d f o r a f i v e day p e r i o d f r om Feb. 25 t o March 1, 1956. The mink r e c e i v i n g the h e r r i n g r a t i o n s were e x c l u d e d s i n c e t h e y a l l had l o s t w e i g h t p r e v i o u s t o t h i a m i n e s u p p l e m e n t a t i o n and a t t h i s t i m e t h e y were r e g a i n i n g t h e i r l o s t w e i g h t . F o r t h i s r e a s o n t h e y had t o be e x c l u d e d f r o m the maintenance c a t e g o r y . A f i v e day p e r i o d was s e l e c t e d f o r r e c o r d i n g f e e d consumption i n t h e hope t h a t i t would p e r m i t some assessment of the v a r i a b i l i t y i n the d a i l y i n t a k e v a l u e s . 63 I t was assumed t h a t t h e body w e i g h t s of t h e mink would not change over t h e s h o r t e x p e r i m e n t a l p e r i o d and as a r e s u l t the mink were o n l y weighed a t t h e b e g i n n i n g of the e x p e r i m e n t . The r e s u l t s of t h e maintenance experiment w h i c h showed no s i g n i -f i c a n t w e i g ht changes d u r i n g t h i s p e r i o d f u r t h e r v a l i d a t e d t h i s a s s u m p t i o n . S i n c e temperature changes can i n f l u e n c e f e e d consump-t i o n (57) the d a i l y minimum and maximum t e m p e r a t u r e s were r e -c o r d e d . The average minimum tem p e r a t u r e over t h e f i v e day p e r i o d was 33.6°F. whereas t h e average maximum d a i l y t e mperature was MD.^F. The s m a l l v a r i a t i o n i n the d a i l y t e m p e r a t u r e over the e x p e r i m e n t a l p e r i o d would reduce the day t o day v a r i a t i o n i n f e e d i n t a k e t h a t might have o c c u r r e d had the t e m p e r a t u r e s been more v a r i a b l e . I t i s p e r t i n e n t t o r e c o r d t h a t t h e a n i m a l s n e s t boxes were bedded w i t h s h a v i n g s and hence no o p p o r t u n i t y was o f f e r e d t o produce a n e s t . More r e c e n t e v i d e n c e s u g g e s t s t h a t f e e d c o n -sumption i s markedly i n f l u e n c e d by n e s t i n g c o n d i t i o n s . Feed consumption was r e c o r d e d on a wet weight b a s i s s i n c e the d r y matter c o n t e n t of the canned r a t i o n s averaged 3 7 . 7 + -2 .1 per c e n t . The e r r o r , i n w e i g h i n g a 1000 gm. mink i s a t l e a s t 2 per cen t s i n c e the s c a l e used was marked o f f i n 20 gm. de-v i a t i o n s . The average d a i l y f e e d consumption of the average a d u l t mink f o r each canned r a t i o n i s g i v e n i n T a b l e 20 . 6h T a b l e 20 Average D a i l y Feed Consumption of the A d u l t Mink R a t i o n Ave. Feed Ave. Gr oup We HAC-2 130 gm. 951 gm. EC-k 121 929 WAC-6 13^ 828 WC-8 130 903 CACA-10 163 913 CAC-12 165 803 CBAC-1>+ 167 903 CBC-16 177 807 Average lh8 880 The f e e d consumption of the mink on the horse meat and whale meat r a t i o n s are s i m i l a r and lower t h a n t h o s e of the a n i -mals on t h e c h i c k e n waste r a t i o n s . I t i s p e r t i n e n t t o note t h a t the average w e i g h t s of the mink on t h e horse meat and t h e whale meat r a t i o n s are h i g h e r t h a n t h o s e on the c h i c k e n waste r a t i o n s but t h e i r f e e d consumption i s l o w e r . I f the r a t i o n s were of the same n u t r i t i v e v a l u e , the mink w i t h the h i g h e r body w e i g h t would be expected t o e a t s l i g h t l y more t h a n t h o s e of lower body w e i g h t . Thus, t h e r e i s an i n d i c a t i o n f r o m T a b l e 20 t h a t t h e r e a r e d i f f e r -ences i n the n u t r i t i v e v a l u e of the v a r i o u s r a t i o n s . The method of p r e s e n t i n g the f e e d consumption d a t a i n T a b l e 20 does not g i v e any r e l a t i o n s h i p between f e e d consumption 65 and body w e i g h t nor does i t g i v e any i n d i c a t i o n of v a r i a b i l i t y . I n order t o e s t a b l i s h the r e l a t i o n s h i p between f o o d consumption and body w e i g h t , t h e average f e e d consumption f o r each mink over t h e f i v e day p e r i o d was p l o t t e d aga.nst i t s body w e i g h t on l o g - l o g paper as shown i n F i g . 5 . The r e g r e s s i o n l i n e r e l a t i n g f e e d consumption, i n g.m . t o body weight i n gm. was c a l c u l a t e d by the method of l e a s t squares f o r t h e 82 mink ( 11 ) . The r e l a t i o n s h i p between f e e d consumption and body w e i g h t f o r a l l t h e mink i n the t r i a l may be e x p r e s s e d by t h e f o l l o w i n g e q u a t i o n : .ho F l = 9.97 W ; + s r = 25 .9$ ; - S r = 20.6$ where F l i s t h e f e e d consumption i n gm. and W i s body w e i g h t i n gm. The c o r r e l a t i o n c o e f f i c i e n t p = .867 . R e g r e s s i o n l i n e s r e l a t i n g f e e d consumption t o body w e i g h t f o r the mink on the v a r i o u s supplementary p r o t e i n groups were a l s o c a l c u l a t e d . These e q u a t i o n s w i t h t h e i r s t a n d a r d e r r o r of e s t i m a t e are p r e s e n t e d i n T a b l e 2 1 . T a b l e 21 R e l a t i o n s h i p Between Feed Consumption and Body Weight P r o t e i n Source R a t i o n s E q u a t i o n S t a n d a r d E r r o r Horse Meat H A C ^ H C - H - F l = 2.39 W*^8 + S r = 2 1 . 8 $ : )|)| Whale Meat WAC-6; WC-8 F l = 6.69 w * +Sr = 21.8 C h i c k e n A CACA -10; C A C - 1 2 F l = 3 . 9 ^ W*^ +Sr = 18.8$; C h i c k e n B CBAC - 1 H - ; CBC-16 F l = 10.33 W*^0 +Sr = 21.8$ .ALL ALL F l = 9.97 W*14"0 +Sr = 25.9$ F l = f e e d consumption i n gm. W = body w e i g h t i n gm. -Sr = 17.9$ -Sr = 17.9$ -Sr = 15.1$ -Sr = 17.2$ -Sr = 20.6$ 66 The r e g r e s s i o n l i n e s i n T a b l e 21 w i t h t h e i r s t a n d a r d e r r o r s i n d i c a t e t h a t t h e r e i s c o n s i d e r a b l e f l u c t u a t i o n i n f e e d consumption at any g i v e n body w e i g h t . T h i s i s a l s o bourne out by the spread of p o i n t s i n F i g . 5 . Another p o i n t t o c o n s i d e r i s t h a t the mink were e a t i n g out of cans and though t h e y were checked d a i l y t h e r e was t h e p o s s i b i l i t y t h a t a mink might have been w i t h -out f e e d f o r a s h o r t p e r i o d . As a r e s u l t the f e e d consumption on the f o l l o w i n g day would be c o n s i d e r a b l y h i g h e r t h a n the p r e -v i o u s day. I t was hoped t h a t t h i s d a i l y f l u c t u a t i o n c o u l d , i n p a r t , be e l i m i n a t e d by a v e r a g i n g the f e e d consumption over t h e f i v e day p e r i o d . The exponent f o r body w e i g h t of the e q u a t i o n r e l a t i n g t h e f e e d consumption of a l l t h e mink t o t h e i r body w e i g h t i s .hO and the exponents of t h e body w e i g h t s f o r t h e e q u a t i o n s of the p r o t e i n s o u r c e s range from ,h0 t o .58 (Table 2 1 ) . The N a t i o n a l R e s e a r c h C o u n c i l N u t r i e n t Requirements f o r Foxes and Minks (*+9) have a suggested d r y matter i n t a k e f o r mature mink on a main-tenance d i e t . T h e i r suggested d r y m atter i n t a k e i s p r e s e n t e d i n A ppendix J , T a b l e 31 and T a b l e 33 . The r e g r e s s i o n l i n e r e l a t i n g body w e i g h t and d r y m a t t e r i n t a k e was c a l c u l a t e d f o r the N a t i o n a l R e s e a r c h C o u n c i l ' s recom-mendation. The r e g r e s s i o n l i n e was F l = ^ . 3 3 W,1+2; + Sr = 6 . 3 $ ; - Sr = 5.9$ where F l i s the d r y m atter i n t a k e i n gm'. and W i s the body w e i g h t i n gm. T h e i r exponent i s i n c l o s e agreement w i t h the one c a l c u l a t e d f r o m the e x p e r i m e n t a l d a t a ( T a b l e 21) w h i c h 67 r e l a t e s the f e e d consumption of a l l the e x p e r i m e n t a l mink t o t h e i r body w e i g h t s . The exponent o b t a i n e d f r o m a l l t he e x p e r i -m e n t a l mink suggest t h a t f o r a d u l t mature mink on a maintenance d i e t , a 100 per c e n t i n c r e a s e i n body w e i g h t s h o u l d l e a d t o a HO per cent i n c r e a s e i n f e e d consumption. The exponents of W o b t a i n e d f o r the v a r i o u s e x p e r i m e n t a l r a t i o n s range from .Ho t o . 5 8 . I t i s apparent t h a t f u r t h e r s t u d i e s on the r e l a t i o n s h i p between f e e d consumption and body w e i g h t are r e q u i r e d b e f o r e any sound i n t e r p r e t a t i o n of t h e p r e s e n t r e s u l t s c a n be o f f e r e d . B rody (11) c i t e s work i n w h i c h i t was found t h a t f e e d consumption v a r i e d as the .50 power of body w e i g h t i n n o n - l a y i n g d o m e s t i c f o w l s , presumably on a maintenance d i e t . He comments t h a t t h e s e r e s u l t s have t o be c o n f i r m e d b e f o r e t h e y c a n be a c c e p -t e d and he s u g g e s t s t h a t the e x p e c t e d exponent s h o u l d be . 7 0 , • s i n c e f e e d consumption s h o u l d be the same f u n c t i o n of body w e i g h t as b a s a l m e t a b o l i s m . Kansky (23) has shown t h a t the r e l a t i o n s h i p between the d r y matter i n t a k e and body w e i g h t of mature S h o r t h o r n cows i s DM = .17 where DM i s the d r y matter i n t a k e of g r a s s i n l b s . and W i s the body w e i g h t i n l b s . Stephenson (59) has measured the f e e d consumption of mature beaver on two d i f f e r e n t r a t i o n s . R e c a l c u l a t i o n of Stephenson's d a t a (59) f o r h i s normal a n i m a l s gave the f o l l o w i n g r e g r e s s i o n l i n e s r e l a t i n g f e e d i n t a k e t o body w e i g h t . 68 • F i g . ? The R e l a t i o n s h i p Between Feed Consumption and Body Weight 69 F o r h i s r a t i o n No. 20H, t h e r e g r e s s i o n l i n e was F l = 17.7 W , 9 ° ; + S r = 15 .3$ ; - Sr = 12.2$ and f o r h i s r a t i o n No. 8 , the r e g r e s s i o n l i n e was F l = 20.6 W 7 ? ; + S r = 13 .0$ ; - Sr = 11.5$ where F l i s the d a i l y f e e d i n t a k e i n gm. and W i s t h e body w e i g h t i n pounds. E s s e n t i a l l y t h e same a n i m a l s were used i n b o t h t r i a l s . Thus, two d i f f e r e n t exponents of body w e i g h t were d e r i v e d f rom f e e d i n g two n e a r l y i d e n t i c a l groups of a n i m a l s two d i f f e r e n t r a t i o n s . These r a t i o n s presumably d i f f e r e d i n n u t r i t i v e v a l u e s i n c e r a t i o n 20*+ proved u n s a t i s -f a c t o r y whereas R a t i o n 8 was adequate f o r the maintenance of the beaver. The exponent of body w e i g h t i n the r e g r e s s i o n between f e e d consumption and body w e i g h t has been shown t o v a r y c o n -s i d e r a b l y . The b i o l o g i c a l s i g n i f i c a n c e of t h e s e d i f f e r e n c e s i s not u n d e r s t o o d . The p r e s e n t r e s u l t s and t h o s e of Stephenson (59) suggest f u r t h e r e x p e r i m e n t a t i o n i s n e c e s s a r y i n order t o permit an adequate u n d e r s t a n d i n g of the r e l a t i o n s h i p between body weight and f e e d consumption. I n t h e p r e s e n t work i t was p o s s i b l e t o e s t i m a t e the i n t a k e of d i g e s t i b l e c a l o r i e s f r o m the r a t i o n c o m p o s i t i o n and the v a l u e s o b t a i n e d i n the d i g e s t i b i l i t y s t u d i e s . The d i g e s t -i b i l i t y t r i a l s were performed on the f r o z e n r a t i o n s and not on the canned r a t i o n s . I t may be argued t h a t the d i g e s t i b l e c a l -o r i e s per gram of d r y matter s h o u l d be h i g h e r i n the canned r a t i o n s . Canning c o u l d make the c e r e a l p o r t i o n more d i g e s t i b l e 70 and hence i n c r e a s e t h e d i g e s t i b l e energy c o n t e n t of the r a t i o n . T h i s r e a s o n i n g i s supported by r e p o r t s f r o m A l b e r t a r a n c h e r s who have been a b l e t o r a i s e mink s u c c e s s f u l l y on d i e t s c o n t a i n i n g a h i g h percentage of cooked c e r e a l ( 6 3 ) . However, Madramootoo (70) has shown w i t h two d i f f e r e n t r a t i o n s t h a t c o o k i n g f o r 30 minutes at 15 l b s . p r e s s u r e does not i n c r e a s e the d i g e s t i b i l i t y . The q u e s t i o n of c o o k i n g c e r e a l s f o r mink i s t h e n s t i l l d e b a t a b l e . I n o r d e r t o c a l c u l a t e the d i g e s t i b l e c a l o r i e s per gm. of r a t i o n , the average d i g e s t i b i l i t i e s f r o m T a b l e 17 were us e d . The average per c e n t c o m p o s i t i o n of t h e r a t i o n s was t a k e n from T a b l e 6 . The f o l l o w i n g v a l u e s f o r d i g e s t i b l e energy were used (11 ) ; P r o t e i n ^ . 0 Cal./gm.; F a t 9 .0 Cal./gm.; and C a r b o h y d r a t e ^ . 0 Cal./gm. The d i g e s t i b l e C a l o r i e s per gm. of d r y r a t i o n a r e p r e s e n t e d i n T a b l e 22 f o r each r a t i o n group. A l s o p r e s e n t e d i n T a b l e 22 are the t o t a l d a i l y i n t a k e of d i g e s t i b l e c a l o r i e s f o r each r a t i o n group whose average d a i l y f e e d consumption was r e -corded i n T a b l e 20 . The d a i l y i n t a k e of d i g e s t i b l e C a l o r i e s f o r each r a t i o n group tends t o be s i m i l a r . The horse meat r a t i o n s have a h i g h d i g e s t i b l e c a l o r i c v a l u e per gm. and as a r e s u l t the f e e d c o n -sumption i s l o w e r . The r e v e r s a l i s t r u e w i t h the c h i c k e n waste r a t i o n s i n t h a t t h e y have a low c a l o r i c v a l u e per gm. and as a r e s u l t f e e d consumption i s h i g h . T h i s d a t a s u g g e s t s t h a t f e e d i n t a k e i s governed by the d i g e s t i b l e c a l o r i c c o n t e n t of the r a t i o n s and the v a r i a t i o n s of f e e d consumption as p r e s e n t e d i n T a b l e 20 are due t o t h i s d i f f e r e n c e . . 7 1 T a b l e 22 D i g e s t i b l e C a l o r i e s per Gram of D r y M a t t e r f o r the R a t i o n Groups Group D i g e s t i b l e C a l . / g m . D a i l y D i g e s t i b l e C a l o r i e s Horse Meat 3.21 152 Whale Meat 2.87 1H-3 C h i c k e n Waste A 2.68 166 C h i c k e n Waste B 2.2h lh$ H e r r i n g 3 • Oh A v e . 152 - 10.8 Another s t u d y of feed consumption of mink r e c e i v i n g the canned r a t i o n s was made d u r i n g a s i x week p e r i o d from M a r . 6 to A p r i l 15, 1956. In t h i s s t u d y , cans of f eed consumed per week were r e c o r d e d f o r a l l the r a t i o n g r o u p s . At t h i s t ime the H e r r i n g groups were supplemented d a i l y w i t h t h i a m i n e . The a v -erage weekly"feed consumption i s r e c o r d e d i n T a b l e 3*+, Appendix J . The average d a i l y d r y matter i n t a k e per mink was c a l c u l a t e d from the average number of cans of f eed consumed, the number of mink per group and the d r y matter content of the canned r a t i o n s . The d a i l y i n t a k e of d i g e s t i b l e C a l o r i e s was c a l c u l a t e d from the d r y matter i n t a k e and the d i g e s t i b l e C a l o r i e s per gm. of d r y r a t i o n as presented i n T a b l e 22. T h i s e s t i m a t i o n of the d a i l y i n t a k e of d i g e s t i b l e C a l -o r i e s should be an e s t i m a t i o n of the d i g e s t i b l e energy r e q u i r e d 72 t o m a i n t a i n an average mink (The mink were i n t h e r a t i o of 5 f e m a l e s t o one m a l e ) . An e s t i m a t i o n of the r e q u i r e m e n t f o r d i g e s t i b l e C a l o r i e s may be made fr o m a t h e o r e t i c a l b a s i s as d e s c r i b e d by Brody (11). The maintenance energy i n d i g e s t i b l e C a l o r i e s tends t o be t w i c e t h e b a s a l energy as c a l c u l a t e d f r o m • 73 B.M. = W* where B.M. i s the b a s a l e n ergy i n C a l o r i e s and W i s body w e i g h t i n K i l o g r a m s . I n o r d e r t o f a c i l i t a t e t h i s c a l c u -l a t i o n the mean body w e i g h t s f o r each r a t i o n group were r e c o r -ded. T h i s c a l c u l a t i o n and the one mentioned above a r e p r e s e n t e d i n T a b l e 23 w h i c h compares the c a l c u l a t e d d i g e s t i b l e energy c o n -sumed t o t h a t d e r i v e d f r o m t w i c e B.M. = 70.5 . The average d a i l y i n t a k e of d i g e s t i b l e C a l o r i e s per mink was 151 - 7.9. The same v a l u e , as computed f r o m the f i v e day f e e d i n g t r i a l was 152 - 10.8 C a l o r i e s ( T a b l e 22). The agree ment between t h e s e two t r i a l s i s e x c e l l e n t . I n a l l c a s e s , the r e c o r d e d d a i l y i n t a k e of d i g e s t i b l e C a l o r i e s per mink was g r e a t e r t h a n t h a t computed from t h e o r y . On the a v e r a g e , the mink r e c e i v e d 16.7 per c e n t above the t h e o r -e t i c a l v a l u e . However, the t h e o r e t i c a l v a l u e does not t a k e i n t o a ccount any energy r e q u i r e d f o r a c t i v i t y . A n o r m a l a l l o w a n c e f o r a c t i v i t y i s about 10 per cent of t h e c a l o r i c i n t a k e but t h i s a l l o w a n c e would p r o b a b l y be t o o low f o r the mink s i n c e i t i s v e r y a c t i v e . A more r e a s o n a b l e v a l u e would be 15 per cent of the c a l o r i c i n t a k e . I f t h i s a s s u m p t i o n were c o r r e c t , t h e n the e x p e r i m e n t a l mink were consuming s u f f i c i e n t C a l o r i e s t o meet t h e i r energy r e q u i r e m e n t s f o r maintenance and a c t i v i t y . 73 An e s t i m a t i o n of the d a i l y i n t a k e of d i g e s t i b l e C a l -o r i e s f o r a 1000 gm. mink may be c a l c u l a t e d . The d a i l y f e e d consumption was computed from the e q u a t i o n r e l a t i n g f e e d c o n -sumption t o body w e i g h t ( T a b l e 21). T h i s was 165 gm. of wet f e e d or 62.3 gm. of d r y m a t t e r , assuming 37.7 per ce n t d r y matter i n the f e e d . The average d i g e s t i b l e C a l o r i e s per gm. of d r y matter i s 2.81 C a l o r i e s . Then the e s t i m a t e d d a i l y i n t a k e of d i g e s t i b l e C a l o r i e s f o r a 1000 gm. mink would be 175. I t i s r e a l i z e d t h a t the c a l c u l a t i o n s performed i n t h i s s e c t i o n are s u b j e c t t o e r r o r because of the assumptions made but t h e y are o n l y i n t e n d e d t o o f f e r an a p p r o x i m a t i o n u n t i l s t u d i e s on t h e e n e r g e t i c s of mink n u t r i t i o n a re i n i t i a t e d . 7k T a b l e 23 Com p a r i s o n of t h e Consumed D i g e s t i b l e C a l o r i e s t o the Computed C a l o r i e s f o r Maintenance Canned R a t i o n P e r Cent Ave. Dry M a t t e r Group Mean Ave. D i g e s t i b l e C a l . ^Computed D i g . Group D r y M a t t e r Consumed per day Body Weight Consumed per day C a l . f o r M a i n t e n a n c e Horse Meat 39 .5 k5.k - 2 .7 gm. 899 gm. lk6 130 Whale Meat 38 .5 52.k ± 8 .2 826 150 120 C h i c k e n A 37.7 59.2 - k.2 77k 159 117" C h i c k e n B 35 .0 62.7 - 11 .1 932 _+0 134-H e r r i n g 39 .8 53.3 - k.l 916 162 130 9 From 2 t i m e s B.M. = 70.5W .73 827 151 - 7 .9 75 VI. Summary The p r i m a r y o b j e c t i v e of t h i s s t u d y was t o compare horse meat, whale meat, two t y p e s of c h i c k e n waste and h e r r i n g as supplementary a n i m a l p r o t e i n s o u r c e s i n r a t i o n s f o r mink d u r i n g maintenance, r e p r o d u c t i o n and growth. P a r t of the r a t i o n s were canned i n an attempt t o p r e v e n t m i c r o b i a l s p o i l a g e . A nother p a r t , c o n t a i n e d a c o m m e r c i a l a n t i o x i d a n t i n the hope t h a t i t would p r e v e n t o x i d a t i v e r a n c i d i t y . The e x p e r i m e n t a l r e s u l t s may be summarized as f o l l o w s : 1 . One hundred and s e v e n t y one female mink of a s s o r t e d c o l o u r phases were f e d the e x p e r i m e n t a l r a t i o n s d u r i n g the main-tenance p e r i o d . There were no s t a t i s t i c a l d i f f e r e n c e s between any of the r a t i o n s . 2 . I n the r e p r o d u c t i v e phase of the e x p e r i m e n t , the mink r e c e i v i n g the canned r a t i o n s had e s s e n t i a l l y complete r e p r o d u c t i v e f a i l u r e . Only 1 2 k i t s were b o r n f r o m 7 9 f e m a l e s b r e d . From th e mink r e c e i v i n g t h e f r o z e n r a t i o n s , 1 9 ^ k i t s were b o r n f r o m 8 8 f e m a l e s b r e d . The average of 2 . 2 k i t s per female was below n o r -mal. The average g e s t a t i o n p e r i o d f o r a l l the mink was 5 3 - ^.0 d a y s . 3 . S i x t y female and 6 0 male k i t s were f e d t h e f r o z e n r a t i o n s d u r i n g the growth phase. The r a t i o n s c o n t a i n i n g Horse Meat, Whale Meat and C h i c k e n Waste A were s t a t i s t i c a l l y s u p e r i o r t o those c o n t a i n i n g C h i c k e n Waste B and H e r r i n g a t p = . 0 1 . The d i f f e r e n c e between the two c h i c k e n wastes has been a t t r i b u t e d t o 76 the v a r i a b i l i t y of t h e c o m p o s i t i o n of c h i c k e n w a s t e s . The below average performance of the mink on the H e r r i n g r a t i o n s was not due t o p r o t e i n of i n f e r i o r q u a l i t y , as e v i d e n c e d by i t s h i g h Net P r o t e i n U t i l i z a t i o n v a l u e , but p r o b a b l y due t o the r e s u l t s of o x i d a t i v e r a n c i d i t y . k. The a n t i o x i d a n t d e p r e s s e d growth of t h e k i t s . T h i s suggests t h a t at the l e v e l u s e d , the a n t i o x i d a n t possessed some degree of t o x i c i t y . 5. The average percentage of t h i a m i n e d e s t r o y e d i n the r a t i o n s d u r i n g a 110 day s t o r a g e p e r i o d at 0°F. was 2 9 . 2 . The average percentage of t h i a m i n e d e s t r o y e d between t h a w i n g the r a t i o n s and subsequent consumption was 1 6 . 0 . The a n t i o x i d a n t d i d not p r o t e c t the d e s t r u c t i o n of t h i a m i n e i n e i t h e r of t h e s e two t r i a l s . 6 . The average per cent d i g e s t i b i l i t y f o r v a r i o u s r a t i o n components were d e t e r m i n e d by the chromic o x i d e method f o r 50 a d u l t female mink r e c e i v i n g t h e f r o z e n r a t i o n s . They were: D i g e s t i b i l i t y C l a s s P e r Cent D i g e s t i b i l i t y F a t T o t a l N i t r o g e n it C a r b o h y d r a t e " 61.5 - 5.1 70.6 - 6 .9 87.9 - 1.9 26.9 - >+.0 7. The Net P r o t e i n U t i l i z a t i o n v a l u e s of t h e f a t e x t r a c t e d supplementary p r o t e i n s o u r c e s were d e t e r m i n e d i n o r d e r t o have an 77 assessment of t h e i r amino a c i d c o m p o s i t i o n . They were: Horse Meat .5H Whale Meat . 5 * C h i c k e n Waste A .>+3 C h i c k e n Waste B .33 H e r r i n g .65 8. The r e l a t i o n s h i p between f e e d consumption and body w e i g h t f o r a l l the mink r e c e i v i n g the canned r a t i o n s was: F l = 9.97 W , I f 0 where F l i s the f e e d consumption i n gm. and W i s the body weight i n gm. R e g r e s s i o n e q u a t i o n s were a l s o d e t e r -mined f o r the o t h e r r a t i o n g r o u p s . 9 . The v a r i a b i l i t y i n f e e d consumption of the mink r e -c e i v i n g the canned r a t i o n s was a t t r i b u t e d t o the d i f f e r e n c e s i n the d i g e s t i b l e energy c o n t e n t s of the r a t i o n s . The average d a i l y d i g e s t i b l e C a l o r i e s f o r mink whose average weight was 827 gm. was c a l c u l a t e d t o be 151 - 7 . 9 . 78 Appendix A k Maintenance Weight Data F o r The Female A d u l t Mink R a t i o n No. of Ave. Wt. Ave. Wt. Ave. Wt. Ave. Wt, Females J a n . 6 Feb.20 Mar. 21 Gained HAF -1 9 792 801 860 68 HAC-2 10 756 799 779 23 HF -3 10 762 875 796 3 k HC-H- 9 712 770 7 L 5 33 WAF-5 10 711 696 7^0 29 Y/AC-6 10 717 802 811 9 L WF-7 9 768 702 807 39 WC-8 10 732 7^9 7*+3 11 CAAF -9 10 7^8 708 752 h CAAC-10 8 70h 7k3 709 5 CAF -11 9 705 711 7 8 L 79 CAC-12 7 788 771 81^- 26 CBAF -13 8 829 796 829 0 CBAC-lif 8 835 806 816 -19 CBF -15 8 789 769 832 h-3 CBC-16 7 783 761 79^ 11 Ave. or T o t a l l k 2 758 766 788 30 k A l l w e i g h t s are i n gm. 79 Appendix B  The H e r r i n g Mink D u r i n g Maintenance T a b l e 2k Wo. of Ave. I n i t i a l Ave. Wt. Ave. Wt. R a t i o n Females Wt. Mar. 2 Loss FAF -17 8 815 gm. 80k gm. 11 gm. FAC -18 8 87*+ ?kl 133 FF-19 8 899 839 60 FC-20 5 858 60k 25k Ave. or T o t a l 29 862 7^7 115 T a b l e 25 Weight Data and Feed Consumption A f t e r V i t a m i n S u p p l e m e n t a t i o n Supplement Females Ave. Wt. Data-gms. ^Ave. Feed i n Gms. per Day Mar.2 Mar.10 Mar.15 P r i o r V i t a m i n s A f t e r V i t a m i n s 132 13k 157 15k Thiamine 9 721 7k9 791 15 F o l i c & B]_ 6 7k3 788 823 62 F o l i c 8 7k0 693 68k 58 1% W.B.C. 6 870 805 837 60 5 Mink on Canned R a t i o n s Only T a b l e 26 Average Weight of H e r r i n g Female Mink R a t i o n J a n . 20 Mar. 2 A p r i l 15 FAF - 17 815 gm. 80k gm. 951 gm. FAC -18 87k 7kl 879 FF - 1 9 899 839 995 FC - 20 858 60k 875 80 Appendix C Mean Body Weight and Feed Consumption of Male Mink  Receiving a Canned Horse Meat and Herring Ration Fig. 1  The Horse Meat Group ihOO 1300 -1600 IkOO 1200 Weeks Fig . 2  The Herring Group wt; Feed t t Began Thiamine 0 6 Weeks 8 1 .10 _ 1500 . 1000 c •H c o •H -P a OT o o T3 <D O) P>4 03 Q) - 1000 . 500 81 Appendix D Reproduction and Yifeaning Data for the Experimental Groups Total Females Kits Kits Kits Born Kits Weaned Ration Females Littered Born Weaned per Female per F< HAF-1 9 if 8 2 0 .9 0 .2 HAC-2 10 2 • 0 0 .0 0 .0 HF-3 9 6 13 7 l A 0.8 HC-^f 8 0 0 0 0 .0 0 .0 WAF-5 10 2 5 0.5 0 .5 WAC-6 9 1 1 1 0.1 0.1 WF-7 9 6 39 30 k . 3 3 .3 WC-8 10 0 0 0 0 .0 0 .0 CAAF-9 10 7 22 18 2 .2 1.8 CAAC-10 8 0 0 0 0 .0 0 .0 CAF-11 9 k 12 6 1.3 0 .7 CAC-12 7 0 0 0 0 .0 0 .0 CBAF-13 8 5 30 27 3.8 3 . L CBAC-l*f 8 0 0 0 0 .0 . 0 .0 CBF-15 8 5 28 27 3 .5 3 A CBC-16 7 0 0 0 0 .0 0 .0 FAF-17 8 3 13 2 1.6 0 .3 FAC-18 8 11 »f l.h 0.5 FF-19 8 if 2h 2L 2.8 3.0 FC-20 if 1 •> * 0 0 .0 0 .0 Total or Ave. 167 206 5153 1.2 0.9 5 7 Kits were used for enzyme studies 82 A p p e n d i x E Growth Data f o r the E x p e r i m e n t a l Groups T a b l e 27 Average W e i g h t s - of t h e Mink D u r i n g Growth Females R a t i o n HAF -1 HF -3 WAF-5 WF-7 CAAF -9 CAF -11 CBAF -13 CBF -15 FAF -17 FF - 1 9 No, •6 6 6 6 6 5 6 6 5 6 June 28 39>+ 3 k 0 333 3^7 351 3 W 3 L 0 set 368 J u l y l k 5 k 0 k 9 2 L97 537 518 5*+2 567 568 502 J u l y _J_Z_ 6k0 607 627 663 620 620 6L7 $ 583 Aug. J L Z -698 687 7 L 0 790 71G 697 723 730 730 627 S e p t . Nov. 28 11 84o 880 933 953 933 1003 1100 1120 973 1007 1012 1 0 2 k 927 8^7 9^0 9 M 968 928 823 853 T o t a l G a i n 531 613 670 773 656 684-507 III 485 Ave. 58 359 526 630 713 9 k 5 956 597 Males HAF -1 6 >+03 HF -3 5 530 WAF-5 6 382 WF-7 6 416 CAAF -9 6 446 CAF -11 6 4 o i CBAF -13 6 y30 CBF -15 6 457 FAF - 17 6 1+50 FF - 1 9 3 347 Ave. 56 426 693 856 602 685 727 638 733 728 723 527 920 1088 ,793 943 900 853 900 913 890 707 1180 1306 997 1230 1126 IO67 1023 1124 1085 807 1593 1832 1397 1587 1533 1487 1460 1413 1537 1280 1697 1952 1447 1760 1690 1607 1450 1503 l 4 l 7 1333 691 891 1095 1512 1585 1294 l 422 1065 1344 1244 1206 1020 1046 967 987 1159 6 A l l w e i g h t s a re i n grams 83 Appendix E  Growth Data f o r the E x p e r i m e n t a l Groups  Fig.. 3 Average Growth Curve of t h e Female K i t s 1200 1000 . 800 -B G •H -P X! M •H CD o 600 PQ !+00 200 0 3 0 D O 90 Days A f t e r Weaning 120 84-Appendix E  Growth Data f o r the E x p e r i m e n t a l Groups  Average Growth Curve of the Male K i t s 85 Appendix F  T e s t F o r S i g n i f i c a n c e W i t h i n a Group 1. P r o t e i n s The a n a l y s i s of v a r i a n c e f o r growth has i n d i c a t e d t h a t t h e r e are d i f f e r e n c e s i n g a i n due t o t h e d i f f e r e n t s upplementary p r o t e i n s o u r c e s . The s i g n i f i c a n c e of the d i f f e r e n c e s may be c a l -c u l a t e d by a m o d i f i c a t i o n of t h e " t " t e s t . Now " t " i s e q u a l t o s " t " = D where D i s t h e d i f f e r e n c e between two means and SE SE i s t he St a n d a r d E r r o r between the two means. The S t a n d a r d E r r o r between two means i n a v a r i a n c e a n a l y s i s i s : the square r o o t of E r r o r V a r i a n c e (2)  No. of v a r i a t e s e n t e r i n g one mean Now the minimum d i f f e r e n c e between any two v a r i a t e means r e q u i r e d f o r s i g n i f i c a n c e = M.S.D. w h i c h i s e q u a l t o : . M.S.D. = E r r o r V a r i a n c e (2) t i m e s " t " @ No. of v a r i a t e s e n t e r i n g one mean p = .05 of e r r o r degrees of freedom, ^ h i s e x p r e s s i o n i s d e r i v e d f r om t h e " t " e x p r e s s i o n where D = ( t ) SE. Any d i f f e r -ence between means w h i c h i s l a r g e r t h a n the c a l c u l a t e d M.S.D. w i l l t h e n have s i g n i f i c a n c e a t t h e p = .05 l e v e l . T h i s c a l c u -l a t i o n i s a p p l i c a b l e t o any l e v e l of p. Fo r t h e p r o t e i n s , M.S.D. i s e q u a l t o : M.S.D. = s q . r o o t of 22*+2^ (2) t i m e s " t " @ p = .01 f o r h d . f . = 33.5 (H.6) = 15H gm. 86 The mean g a i n s f o r the f i v e s u pplementary p r o t e i n groups were: Horse 965 gm. Whale 963 C h i c k e n A 9H-B C h i c k e n B 786 H e r r i n g 729 The mean d i f f e r e n c e between Horse and Whale i s 2 gm.; Horse and C h i c k e n A i s 17 gm.; Horse and C h i c k e n B i s 179 gm.; and Horse and H e r r i n g i s 236 gm.; Whale and C h i c k e n B i s 177 gm.; Whale and H e r r i n g i s 23H gm. The mean d i f f e r e n c e between C h i c k e n A and C h i c k e n B i s 162 gm.; C h i c k e n A and H e r r i n g i s 219 gm. The mean d i f f e r e n c e between C h i c k e n B and H e r r i n g i s 57 gm. A mean d i f f e r e n c e g r e a t e r t h a n 15*+ gm. i n d i c a t e s s i g n i f i c a n c e between the means a t p = .01. 2. I n t e r a c t i o n between Sex and P r o t e i n s The M.S.D. f o r t h e i n t e r a c t i o n between Sex and P r o t e i n s a t p = .05 was c a l c u l a t e d t o be 132 gm. The mean g a i n s f o r t h e fem a l e s and males r e c e i v i n g d i f f e r e n t s u pplementary p r o t e i n s o u r c e s were: Females Males Horse 572 gm. 1358 gm. Whale 722 1205 C h i c k e n A 670 1225 C h i c k e n B 539 1033 H e r r i n g H83 977 F o r t h e f e m a l e s the mean d i f f e r e n c e between Horse and Whale i s 150 gm.; Horse and C h i c k e n A i s 98 gm.; Horse and C h i c k e n B i s 63 gm.; Horse and H e r r i n g i s 89 gm. The mean d i f f e r e n c e 87 between Whale and C h i c k e n A i s 52 gm.; Whale and C h i c k e n B i s 183 gm.; Whale and H e r r i n g i s 239 gm. The mean d i f f e r e n c e be-tween C h i c k e n A and C h i c k e n B i s 131 gm.; C h i c k e n A and H e r r i n g i s I87 gm. The mean d i f f e r e n c e between C h i c k e n B and H e r r i n g i s 56 gm. F o r the males the mean d i f f e r e n c e between Horse and Whale i s 153 gm.; Horse and C h i c k e n A i s 133 gm.; Horse and C h i c k e n B i s 325 gm.; Horse and H e r r i n g i s H-79 gm. The mean d i f f e r e n c e between Whale and C h i c k e n A i s 20 gm.; Whale and C h i c k e n B i s 172 gm.; Whale and H e r r i n g i s 228 gm. The mean d i f f e r e n c e between C h i c k e n A and C h i c k e n B i s 192 gm.; C h i c k e n A and H e r r i n g i s 2H8 gm. The mean d i f f e r e n c e between C h i c k e n B and H e r r i n g i s 56 gm. Fo r s i g n i f i c a n c e between t h e means of any two r a t i o n s , t h e d i f f e r e n c e must be g r e a t e r t h a n 132 gms. 88 A p p e n d i x G  Pr o c e d u r e f o r Thiamine D e t e r m i n a t i o n s There a r e many methods f o r t h e a s s a y of t h i a m i n e w h i c h may be c l a s s i f i e d i n t o a n i m a l , m i c r o b i o l o g i c a l , c h e m i c a l and p h y s i c a l methods. The a n i m a l methods are t e d i o u s and the r e -s u l t s v a r y c o n s i d e r a b l y . The m i c r o b i o l o g i c a l methods are much more r a p i d and a c c u r a t e but t h e main d i s a d v a n t a g e i s the t e n -dency f o r s u b s t a n c e s o t h e r t h a n t h i a m i n e t o re s p o n d i n the same way as the v i t a m i n , and as a r e s u l t t h e v a l u e s may be h i g h . C o r r e c t i o n b l a n k s have improved th e s e methods c o n s i d e r a b l y but the methods are not t o o a p p l i c a b l e f o r r o u t i n e d e t e r m i n a t i o n s . C h e m i c a l a n a l y s i s are c o n s i d e r e d t o be more a p p l i c a b l e t o r o u t i n e d e t e r m i n a t i o n s t h a n most o t h e r methods. The two main c h e m i c a l methods are based on'colourimetry and f l o u r i m e t r y . The thiochrome f l u o r i m e t r i c method i s more w i d e l y a p p l i c a b l e t o fo o d s and f e e d p r o d u c t s than are the c o l o r m e t r i c methods. P h y s i c a l methods, based on s p e c t r o p h o t o m e t e r s , a re o n l y used f o r r e l a t i v e l y pure s o l u t i o n s of t h i a m i n e . The method chosen f o r the as s a y of t h i a m i n e , as recom-mended by t h e A s s o c i a t i o n of V i t a m i n C h e m i s t s , was the t h i o -chrome procedure because of i t s a d a p t a b i l i t y t o f e e d p r o d u c t s and i t s ease f o r r o u t i n e a n a l y s e s w h i c h o c c u r r e d f rom w e e k l y t o monthly time i n t e r v a l s . 89 The procedure f o l l o w e d was i d e n t i c a l t o t h a t i n the r e f e r e n c e (1*+) except f o r the f o l l o w i n g m o d i f i c a t i o n s : (1) Reagents I s o b u t y l a l c o h o l was p u r i f i e d i n the f o l l o w i n g manner t o remove any f l o u r e s c e n s e ( 5 D • I s o b u t y l a l c o h o l was d r i e d by s h a k i n g w i t h anhydrous sodium s u l f a t e . The m i x t u r e was t h e n shaken f o r f i v e minutes w i t h 5 grams of N o r i t per 100 m l . of i s o b u t y l a l c o h o l . A f t e r f i l t r a t i o n , t h e i s o b u t y l a l c o h o l was d i s t i l l e d i n an a l l g l a s s d i s t i l l i n g a p p a r a t u s and the f r a c t i o n b o i l i n g between 105-108°C. was c o l l e c t e d . (2) P r o c e d u r e (a) E x t r a c t i o n The f l u o r o m e t r i c attachment f o r t h e Beckman, Model DU S p e c t r o p h o t o m e t e r was used t o measure the f l o u r e s c e n c e produced by t h i o c h r o m e . I t was e s t a b l i s h e d t h a t t h e f l o u r o m e t r i c a t t a c h -ment was about one h a l f as s e n s i t i v e as the f l o u r o m e t e r s recom-mend f o r the p r o c e d u r e . As a consequence, the i n i t i a l sample had t o c o n t a i n 20 t o 60 meg. of t h i a m i n e i n s t e a d of 10 t o 30 meg. F o r r o u t i n e t h i a m i n e a n a l y s i s on the r a t i o n s the sample s i z e was 30 gm. because of the i n s e n s i t i v i t y of t h e f l o u r o m e t e r and the low i n i t i a l t h i a m i n e c o n t e n t of the r a t i o n s . Because of the l a r g e r sample s i z e , t h e a c i d h y d r o l y s i s was extended from 30 t o V? minutes i n o r d e r t o ensure complete s o l u t i o n of the v a r i o u s forms of t h i a m i n e . The e nzymatic h y d r o l y s i s was an o v e r - n i g h t h y d r o l y s i s . A f t e r e nzymatic h y d r o l y s i s , the e x t r a c t s were c e n -t r i f u g e d i n p l a s t i c c e n t r i f u g e tubes and t h e n f i l t e r e d . ' 90 (b) P u r i f i c a t i o n No changes were made i n the p u r i f i c a t i o n procedure but some t e c h n i q u e s a r e w o r t h n o t i n g . To a v o i d banding w h i l e f i l l i n g t he a d s o r p t i o n columns the f o l l o w i n g t e c h n i q u e was found s a t i s -f a c t o r y . A s m a l l wad of g l a s s w o o l and a s m a l l c o r k were i n -s e r t e d i n t o the s m a l l end of the column. W i t h t h e column f i l l e d t o one i n c h f r o m the t o p w i t h d i s t i l l e d w a t e r , a c t i v a t e d d e c a l s o was s l o w l y added w h i l e the w a t e r - d e c a l s o m i x t u r e i n the column was s t i r r e d v i g o r o u s l y w i t h a s t i r r i n g r o d . The c o n t i n u o u s s t i r r i n g enabled the d e c a l s o t o s e t t l e a t a u n i f o r m r a t e and thus a v o i d b a n d i n g . I t was e s t a b l i s h e d t h a t p u r i f i c a t i o n by the columns _n was n e c e s s a r y . The t e s t t h i a m i n e s o l u t i o n c o n t a i n e d 5 x 10 'gm. t h i a m i n e h y d r o c h l o r i d e per m l . and was prepared by d i l u t i n g t o 100 c c . w i t h d i s t i l l e d w a t e r , 10 .0 m l . of i n t e r m e d i a t e thiamine s o l u t i o n p l u s 75 m l . of 0 . IN H2SOL and 5 m l . of Sodium A c e t a t e s o l u t i o n . S m a l l , f u n n e l s , made f r o m t e s t t u b e s , were used t o c o l l e c t the K C l e l u t a t e f rom the columns i n t o the 25 m l . v o l u -m e t r i c f l a s k s . The use of th e s e f u n n e l s p r e v e n t e d t h e f o r -m a t i o n of a i r t r a p s i n t h e v o l u m e t r i c f l a s k s . ( c ) C o n v e r s i o n t o Thiochrome Ten ml. of t h e a c i d K C l e l u t a t e and 5 m l . of a l k a l i n e f e r r i c y a n i d e were used f o r the f o r m a t i o n of t h i o c h r o m e . The h i g h e r r e l a t i v e c o n c e n t r a t i o n of f e r r i c y a n i d e was used i n o r d e r 91 t o ensure the complete c o n v e r s i o n of t h i a m i n e t o t h i o c h r o m e . The amount of thiochrome t o be o x i d i z e d was l a r g e r because of the i n s e n s i t i v i t y of the f l o u r o m e t e r . (d) Measurement of Thiochrome Thiochrome was measured by t h e f l o u o r o m e t r i c a t t a c h -ment of the Beckman, Model DU Sp e c t r o p h o t o m e t e r u t i l i z i n g the proper f i l t e r s and t h e s e n s i t i v i t y knob s e t a t 0 . 1 . (3) Sample P r e p a r a t i o n A p p r o x i m a t e l y 500 gm. of sample were t a k e n randomly f r o m a b l o c k of f e e d i n the f e e d s t o r a g e r e f r i g e r a t o r . The sample was c u t i n t o s m a l l p i e c e s w i t h a k n i f e and t h e n ground i n a Hobart meat g r i n d e r f r o m w h i c h t h e assay samples were t a k e n . A l l samples were a n a l y z e d i n d u p l i c a t e and the a s s a y s were u s u a l l y w i t h i n 5 per c e n t of one a n o t h e r . 92 Appendix H D i g e s t i h j L i t v S t u d i e s on t h e F r o z e n R a t i o n s (1) Methods and M a t e r i a l s F i v e a d u l t female mink f r o m each of t h e t e n f r o z e n r a t i o n s ( T a ble 7) were f e d f o r a 3 day p e r i o d ( J u l y 22 -25 , 1956) t h e i r r e g u l a r r a t i o n s w h i c h c o n t a i n e d a p p r o x i m a t e l y hO mg. of chromic o x i d e per gm. of d r y r a t i o n . The chromic o x i d e was mixed i n t o a 3 day f e e d s u p p l y by means of a Hobart mixer u n t i l a u n i f o r m g r e e n c o l o u r r e s u l t e d . The f e e d was k e p t c h i l l e d i n the r e f r i g e r a t o r between f e e d i n g and j u s t p r i o r t o f e e d i n g , the f e e d was re-mixed t o ensure u n i f o r m d i s t r i b u t i o n of the i n d i c a t o r . The f a e c e s were c o l l e c t e d on wax paper w h i c h was p l a c e d below the mink cages. At the end of the c o l l e c t i o n p e r i o d , samples of f e e d and f a e c e s were c o l l e c t e d , d r i e d a t 100°C. f o r hQ hours and t h e n ground i n a W i l e y M i l l , u s i n g the hO mesh s c r e e n . The samples were s t o r e d i n t i g h t l y s t o p p e r e d b o t t l e s u n t i l a n a l y z e d . (2) C h e m i c a l P r o c e d u r e s B o t h Worthen (65) and Madramootoo (*+2) have shown t h a t t h e chromic o x i d e method i s s a t i s f a c t o r y f o r measuring t h e d i g e s t i b i l i t y of mink r a t i o n s and t h a t the method i s comparable t o t h e t o t a l c o l l e c t i o n method. Chromic o x i d e i n the f e e d and f a e c e s was d e t e r m i n e d by the method as d e s c r i b e d by B o l i n ( 10 ) . T h i s method has been used s u c c e s s f u l l y i n the A n i m a l N u t r i t i o n L a b o r a t o r y , U n i v e r s i t y of B r i t i s h C o l u m b i a , i n s t u d y i n g the 93 d i g e s t i b i l i t y of a w h e a t - h e r r i n g r a t i o n when f e d t o mink ( 65 ) . The Coleman s p e c t r o p h o t o m e t e r was used i n p r e p a r i n g a s t a n d a r d c u r v e between t h e c o n c e n t r a t i o n of 0.2 t o 0.14 mg. of chromic o x i d e per m l . of s o l u t i o n . A s t r a i g h t l i n e r e l a t i o n s h i p e x i s t e d between the l o g a r i t h i m of the per cen t t r a n s m i s s i o n and the c o n -c e n t r a t i o n of chromic o x i d e . N i t r o g e n i n the f e e d and f a e c e s were d e t e r m i n e d by a s t a n d a r d method (46). F a t i n t h e f e e d and f a e c e s was d e t e r -mined by the method d e s c r i b e d by B a i l e y (4). The per cen t t o t a l d i g e s t i b i l i t y , n i t r o g e n d i g e s t i b i l i t y , f a t d i g e s t i b i l i t y and " c a r b o h y d r a t e " d i g e s t i b i l i t y f o r each mink appears i n T a b l e 28 . The t o t a l d i g e s t i b i l i t y may be c a l c u l a t e d f r o m the d a t a so o b t a i n e d . F o r convenience the f o l l o w i n g f o r m u l a was d e r i v e d . P e r Cent T o t a l D i g e s t i b i l i t y = 100 ( 1 - per c e n t C r e t i n f e e d per c e n t Cr203in f a e c e s ) The i n d i v i d u a l n i t r o g e n d i g e s t i b i l i t i e s f o r each mink can be c a l c u l a t e d as f o l l o w s : A sample c a l c u l a t i o n i s g i v e n f o r mink No. 1 (T a b l e 2 8 ) . 1 gm. f e e d has 0 .0465 gm. N = 0.041 gm. Cr203 1 gm. f a e c e s has 0 .0352 gm. N = O.OI38 gm. Cr . 2 03 F o r 1 gm. Cr 2 0 ^ i n the f e e d t h e r e i s 0.0465 = 11.34 gm. N 0.041 F o r 1 gm. Cr203 i n f a e c e s t h e r e i s 0.0352 = 2.55 gm. N 0.0138 N i t r o g e n Absorbed = 11.34-2.55 = 8.79 gm. N Per c e n t n i t r o g e n d i g e s t e d = 8.79(100) = 77.5 per c e n t . 11.34 94 The f o l l o w i n g d e r i v e d f o r m u l a can be used t o g ive d i r e c t l y the n i t r o g e n d i g e s t e d . Per cent n i t r o g e n d i g e s t e d = (1 - JN i n faeces . % Cr?0^ i n feed)100 % Cr2 0 3 i n f aeces % N i n feed The fet'djgsstibility was c a l c u l a t e d i n the same manner as the n i t r o g e n d i g e s t i b i l i t y . The term "carbohydrate" used i n t h i s s t u d y r e q u i r e s some e x p l a n a t i o n . When a r a t i o n i s viewed on the b a s i s of i t s proximate c o m p o s i t i o n , the main c o n s t i t u e n t s are p r o t e i n ( N i t r o g e n 6 . 2 5 ) , f a t or e ther e x t r a c t , w a t e r , a s h , f i b r e and n i t r o g e n f r e e e x t r a c t . In t h i s s tudy the term " c a r b o h y d r a t e " r e f e r s t o the f i b r e and n i t r o g e n f r e e e x t r a c t terms of a proximate a n a l y s i s s i n c e these two are c h i e f l y composed of c a r b o h y d r a t e s . S i n c e t h i s s tudy was done on mature a d u l t mink and the ash content of the r a t i o n was low, the per cent d i g e s t i b i l i t y of the ash was assumed to be z e r o f o r the purpose of c a l c u l a t i n g the per cent "carbohydrate" d i g e s t i b i l i t y . "Carbohydrate" d i g e s t i b i l i t y can then be c a l c u l a t e d from the per cent t o t a l d i g e s t i b i l i t y , n i t r o g e n d i g e s t i b i l i t y , f a t d i g e s t i b i l i t y , per cent feed f a t and the per cent feed n i t r o g e n as d e s c r i b e d i n the f o l l o w i n g f o r m u l a : "Carbohydrate" D i g e s t i b i l i t y = Per cent t o t a l d i g e s t i b i l i t y - f{% feed f a t ) ( f a t d i g e s t i b i l i t y ) 100 plus (% Feed N i t r o g e n ) ( 6 . 2 5 ) ( N i t r o g e n d i g e s t i b i l i t y ) 1 100 A sample c a l c u l a t i o n f o r mink No. 1 i s : "Carbohydrate" D i g e s t i b i l i t y = 70.3 - [ ( 17 .3 ) (92 .2 ) p lus ( 4 . 7 ) ( 6 . 2 5 ) ( 7 7 . 5 ) ] = 31 .5 per c e n t . 100 100 T a b l e 28 . T o t a l D i g e s t i b i l i t y . N i t r o g e n D i g e s t i b i l i t y . F a t D i g e s t i b i l i t y and " C a r b o h y d r a t e D i g e s t i b i l i t y " f o r I n d i v i d u a l Mink Mink P e r Cent Per Cent R a t i o n No. F a e c a l N F a t F a e c a l HAF-1 1 2 3 h 5 HF-3 25 26 27 28 30 WAF-5 H-9 50 51 52 53 WF-7 73 7k 75 77 79 CAAF-9 97 98 99 100 101 CAF-11 120 121 122 12h 125 CBAF-131H-5 lk6 lh7 IkQ lk9 CBF-15 169 170 171 172 173 FAF-17 196 198 199 200 201 FF-19 217 218 219 220 221 3,5 1:1 3.k k.7 k.2 k.l .3 .0 3.1 k.5 3.3 3.3 2.7 2.2 k.l k.6 3.6 3.8 2.8 3.0 2.9 k.6 5.3 k.5 3.8 3.9 k.5 3.7 k.O 3.8 £ 1 k.6 k.6 k.5 3.8 k.5 3.9 k.l k.7 k.9 2.9 3.9 2.7 3.0 2.6 k.3 2.6 k.5 k.O k.Q 2.9 k.5 3.5 5.2 3-3 2.8 k.2 5.8 7.2 k.l 3.3 k.5 k.9 3.8 k.5 5.5 3.5 k.Q k.Q 1.8 k.5 2 4 2.5 3.5 I'l 3.8 I f . l 5.1 5.0 3.2 3.2 3.2 3.3 3.9 k.Q 3.3 3.7 6.0 l \ l k.3 3.5 3.5 k.3 5.3 P e r Cent Feed Cr?03 k.l k.l k.l k.l k.l k.2 k.2 k.2 k.2 k.2 k.9 k.9 k.9 k.9 k.9 k.O k.O k.O k.O k.O k.k k.k k.k k.k k.k k.l k.l k.l k.l k.l k.7 k.7 k.7 k.7 k.7 k.6 k.6 k.6 k.6-k.6 k.5 k.5 ^ k.5 k.2 k.2 k.2 k.2 k.2 P e r Cent Faeces C2O3 13.8 13.7 11.1 10.1 10.2 10.6 17.5 13.9 18.6 15.8 13.9 10.9 13.1 12.6 13.8 11.8 8.8 10.3 9.0 10.7 lk.6 9.6 11. k 11.6 10.3 9.6 11.9 12.6 9.3 9.8 12. k 11.6 12.1 12.6 lk.1 10.9 12.1 11.5 11.0 9.9 8.6 9.7 10.9 10.0 8.3 11.6 13.2 13. k 7.7 9.7 P e r Cent P e r Cent P e r Cent T o t a l N i t r o g e n F a t C a l c u l a t e d Feed N Feed F a t D i g e s t i b i l i t y D i g e s t i b i l i t y D i g e s t i b i l i t y "CHO" D i g e s t i b i l i t y k.7 k.7 k.7 k.7 k.7 5.3 5.3 5.3 5.3 5.3 k.9 k.9 ^ . 9 k.9 k.9 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.2 5.0 5.0 5.0 5.0 5.0 5.3 5.3 5.3 5.3 5.7 5.7 5.7 5.7 5.7 k.6 k.6 k.6 k.6 k.6 k.k k.k k.k k.k k.k 17.3 17.3 17.3 17.3 17.3 1 9 . 5 1 9 . 5 1 9 . 5 1 9 . 5 1 9 . 5 15.0 15.0 15.0 15.0 15.0 11.2 11.2 11.2 11.2 11.2 9 . 7 9 . 7 9 . 7 9 . 7 .9.7 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 10.0 12.7 12.7 12.7 12.7 12.7 lk.5 lk.5 lk.5 lk.5 lk.5 19.8 19.8 1 9 . 8 19.8 19.8 70.3 70.1 63.I 59. k 59.8 60. U-76.0 69.8 77.k 73.k 6k.5 65.0 62.6 6 l.l 6k.5 66.1 5k.5 61.2 55.6 62.6 69.9 5k.2 61. k $2.1 57.3 57.3 65.5 67.5 55.9 58.2 62.1 59.5 61.2 62.7 66.7 57.8 62.0 60.0 58.2 53.5 k7.7 53.6 58.7 6.0 63.8 68.2 68.7 k5.k 56.7 77.5 79.0 6k.O 70.0 78.5 68.6 82.8 69.6 83.O Qk.5 67.7 69.5 75.1 Qk.2 73.2 59.6 72.6 71.2 79.5 82.5 7k.3 65.6 61.0 63.2 67. k 73.0 70.2 67.2 66.2 72.6 59.2 68.2 67.7 71.7 66.6 7k.6 68.9 71.6 66.5 k6.3 k9.9 7k.l 61.5 68.3 75.0 81.8 81.6 k7.l 7k.k 92.2 93.1 89.7 93.2 89.5 92.9 93.6 9k.9 96.7 9k.3 89.9 82.6 82.0 89. k 92.0 Q6.k 80.2 86.8 82.1 81.6 89.1 77.3 81.9 93.0 80.2 89.3 92.3 88.6 86.8 82.H 85.6 83.3 8 0 . 2 81.3 Q9.k Q9.k 90.if 89.6 87.2 82.if 88.1 88.6 82.9 87.9 8if.3 9 2 . 1 9k.k 9k.5 88.1 88A 31.5 30.8 28.8 22.7 21.2 1 9 . 6 30.3 28.2 31.3 27.0 30.3 31.3 27.3 23.7 2k.9 32.6 26.1 27.9 23.3 27.7 3 .^5 22.6 32.3 33.3 2 9 . 0 27.3 33.5 36.7 26.2 29.3 29. k 31.6 30.6 32.2 3H-.0 22.7 23.9 2if.l 21.6 19.3 21.6 26.5 25. k 2k.6 lk.2 25.0 27.0 27.6 15.0 18.7 96 Appendix I The Net P r o t e i n U t i l i z a t i o n of the Supplementary P r o t e i n s ( 1 .) P r e p a r a t i o n of the Samples About 1000 gm. of each p r o t e i n sample were d r i e d a t 60°C. i n a t u n n e l d r i e r . Each sample was t h e n b r o k e n i n t o f i n e p i e c e s , wrapped i n f i l t e r paper and cheese c l o t h and e x t r a c t e d t e n t i m e s w i t h e t h y l e n e d i c h l o r i d e i n the l a r g e f a t e x t r a c t o r (12 h o u r s ) . The f a t was removed t o ensure a u n i f o r m sample s i n c e the p r o t e i n s v a r i e d i n t h e i r f a t c o n t e n t . The samples were a i r d r i e d and t h e n ground i n t o a f i n e powder i n a W i l e y hammer m i l l . D u p l i c a t e samples of each p r o t e i n s o u r c e were a n a l y z e d f o r p r o t e i n (N x 6 .25) ) by a s t a n d a r d method (k6). The average r e s u l t s of the per c e n t p r o t e i n of the f a t e x t r a c t e d supplementary p r o t e i n s o u r c e s are p r e s e n t e d i n T a b l e 29. T a b l e 29 Average Per Cent P r o t e i n o f the F a t E x t r a c t e d P r o t e i n S o u r c e s  P r o t e i n Source P e r Cent P r o t e i n Horse Meat Whale Meat C h i c k e n Waste A C h i c k e n Waste B H e r r i n g C a s e i n ( V i t a m i n F r e e ) 82.2 86.6 67 .1 59. V 79.7 91 .0 97 (2 . ) Method of A s s a y The method of a s s a y i n g the net p r o t e i n u t i l i z a t i o n of the supplementary p r o t e i n s o u r c e s i s e s s e n t i a l l y t he method of M i l l e r and Bender (47) as m o d i f i e d by R o b e r t s o n (52) f o r the W i s t a r R a t . D e t a i l s of the method are d e s c r i b e d under E x p e r i -m e n t a l . ( 3 .) E x p e r i m e n t a l (a) A n i m a l s The r a t s used were of the W i s t a r s t r a i n whichware weaned a t 20 days and f e d f o r a week p r i o r t o the expe r i m e n t on a s t o c k r a t i o n . Each e x p e r i m e n t a l group c o n s i s t e d of 3 f e m a l e s whose i n i t i a l w e i g h t s were between 65-70 gm. and 3 males whose i n i t i a l w e i g h t s were between 65-70 gm. The t o t a l i n i t i a l w e i g h t s of a l l the groups were b a l a n c e d w i t h r e s p e c t t o one a n o t h e r . There were 7 e x p e r i m e n t a l groups of r a t s ; one group f o r each of the f i v e s upplementary p r o t e i n s t o be t e s t e d , one group on a known p r o t e i n , c a s e i n , t o s e r v e as a c o n t r o l and one group on a n o n - p r o t e i n d i e t . The a n i m a l s were housed i n i n d i v i d u a l pans and were p r o v i d e d w i t h f r e s h water d a i l y . (b) R a t i o n s The M i l l e r and Bender as s a y method (47) r e q u i r e s t h e t e s t p r o t e i n s t o be f e d a t the 10 per cen t l e v e l i n a common n o n - p r o t e i n b a s a l r a t i o n w h i c h i s f e d t o the n o n - p r o t e i n group. The c o m p o s i t i o n of the n o n - p r o t e i n b a s a l r a t i o n i s g i v e n i n Ta b l e 30 . 98 T a b l e 30 C o m p o s i t i o n of the N o n - P r o t e i n B a s a l R a t i o n L a r d 22.3 Corn S t a r c h 61 .2 Sucrose 7 .5 V i t a m i n M ix (NBC) 1.5 S a l t s (U.S.P . No. 2) 7 .5 100.0 gm. Each e x p e r i m e n t a l d i e t , w i t h t h e e x c e p t i o n of the n o n - p r o t e i n d i e t , was a d j u s t e d t o the 10 per c e n t p r o t e i n l e v e l w i t h the r e s p e c t i v e p r o t e i n s o u r c e , ( c ) P r o c e d u r e Each e x p e r i m e n t a l group was f e d t h e i r r e s p e c t i v e d i e t f o r seven d a y s . Weight gained or l o s t and t o t a l f e e d consump-t i o n were r e c o r d e d f o r each r a t . At the end of t h e e x p e r i m e n t a l p e r i o d , the r a t s were k i l l e d w i t h c h l o r o f o r m and the a b d o m i n a l , t h o r a c i c and c r a n i a l c a v i t i e s were opened by i n c i s i o n w i t h s c i s s o r s . The r a t s were t h e n d r i e d a t 105 deg. C. f o r 48 hours i n the t u n n e l d r i e r i n order t o d e t e r m i n e body water c o n t e n t . The n i t r o g e n c o n t e n t of the r a t i o n s were d e t e r m i n e d by a s t a n d a r d method ( 4 6 ) . F i n a l w e i g h t , i n i t i a l w e i g h t , d r y w e i g h t , body n i t r o g e n , f e e d consumption, per ce n t n i t r o g e n of the r a t i o n s and group t o t a l s are g i v e n i n T a b l e 3 1 . 99 (d) C a l c u l a t i o n s Body n i t r o g e n was c a l c u l a t e d from the body water con-t e n t of the r a t s . M i l l e r and Bender (47) have shown a h i g h c o r r e l a t i o n between body n i t r o g e n and body w a t e r f o r r a t s of the hooded s t r a i n w h i c h were f r o m 33-57 days o l d . R o b e r t s o n (52) has v e r i f i e d t h i s r e l a t i o n s h i p i n t h e W i s t a r r a t by d e t e r m i n i n g the n i t r o g e n t o water r a t i o i n 33 r a t s whose w e i g h t s ranged from 40-100 gm. and developed the f o l l o w i n g e q u a t i o n f o r the c a l c u l a t i o n of body n i t r o g e n f r o m body w a t e r . y = 27.89 x 1 , 0 7 7 y = mg. body n i t r o g e n + S r = 3.74$ x = gm. body water - S r = 3.61$ Prom the above e q u a t i o n t h e body n i t r o g e n of each r a t was c a l -c u l a t e d . The net p r o t e i n u t i l i z a t i o n (N.P.U.) was d e t e r m i n e d f r o m the f o l l o w i n g e q u a t i o n as p r e s e n t e d by M i l l e r and Bender (47). N.P.U. = B - ( B k - 1^) I B and B k are the t o t a l body n i t r o g e n of t h e a n i m a l s on t h e t e s t and n o n - p r o t e i n d i e t s r e s p e c t i v e l y , and I and I k are the n i t r o g e n i n t a k e of the two gr o u p s . 100 Table 31 Data For Net P r o t e i n U t i l i z a t i o n C a l c u l a t i o n s P r o t e i n  Source Horse Meat 9fcN = 1 . 6 5 Rat F i n a l I n i t i a l Dry No. Wt. Wt. Wt. Gm. Gm. Gm. I f 2 f 3 f, 4 m 5 m 6 m 88 69 82 75 V 87 86 £ 5 63 62 71 70 68 22 28 23 23 28 28 Body N i t r o g e n mg. 1758 2037 1959 2037 2244 2203 Feed Consumption Gm. 35 52 46 49 54 58 T o t a l 399 12238 294 Whale 1 f 76 63 24 1959 43 Meat 2 f 80 67 27 2000 48 t/oN = 1.60 3 f 83 65 27 2123 54 4 m' 83 69 26 2163 50 "5 m 77 67 25 1959 49 6 m 81 70 25 2123 59 T o t a l 401 12327 303 Chicken Waste A 96N = 1.50 1 2 3 4 I f f f m m m 74 P 67 76 l l 65 62 62 69 65 73 24 25 20 23 23 28 1880 1880 1758 2000 2037 2123 58 49 53 43 49 54 T o t a l 396 , I I678 306 Chicken 1 f 74 26 1758 58 Waste B 2 f 75 62 24 1923 49 9*>N = 1.75 3 f 67 62 25 1553 53 4 m 76 69 27 1837 5 m 77 65 23 2037 49 6 m 86 73 24 2366 54 T o t a l 396 11477 306 7 f = female 88 m = male 101 Table 3 1 (Continued) F i n a l I n i t i a l Dry P r o t e i n Rat Wt. Wt. Wt. Source No. Gm. Gm. Gmf H e r r i n g 1 f 8 0 6 5 2 3 F^W = 1 . 6 0 2 f 8 4 6 6 2 7 3 f 7 4 60 2 4 4 m 85 7 1 28 5 m 7 7 62 2 3 6 m 9 2 7 2 2 8 T o t a l 3 9 6 Body Feed N i t r o g e n Consumption Gm. 2163 49 2163 4 8 1880 47 2163 54 2 0 3 7 46 2 4 4 9 56 12855 300 C a s e i n 1 f 69 60 20 1837 4 6 9fcN = 1.60 2 f 83 65 27 2123 56 3 f 80 63 26 2037 4 8 4 m 86 65 27 2 2 4 4 60 5 m 81 63 26 2 0 8 0 52 6 m 88 77 26 2366 4 2 T o t a l 393 304 Non- 1 f P r o t e i n 2 f Q6N - = 0.00 3 f 4 m 4 m 4 m T o t a l 54 61 16 59 66 17 56 63 16 59 67 16 62 70 19 6 4 71 19 398 1 4 0 0 43 1556 23 1469 25 1596 31 1596 36 2101 38 9718 196 102 Appendix J The R e l a t i o n s h i p Between Feed Consumption and Body Weight T a b l e ^2 N a t i o n a l R e s e a r c h C o u n c i l D a i l y D ry M a t t e r I n t a k e f o r Mink on a Maintenance D i e t (11) Wt. l b s . Food l b s . Wt. l b s . Food l b s . U n d e r - l b s . 2.0 .18 1.5 .15 l b s . 2.0 - 3.0 .19 1.5 - 2.0 .16 Over l b s . 3.0 .20 2.0 .17 T a b l e 32 was r e c a l c u l a t e d t o g i v e an average r e l a t i o n -s h i p between body w e i g h t and d r y matter i n t a k e and t h i s i s r e p -r e s e n t e d i n Table 33. T a b l e 33 Computed N a t i o n a l R e s e a r c h C o u n c i l R e l a t i o n s h i p Between Body Weight and Feed I n t a k e Wt. l b s . Food l b s . 1.5 .15 1.75 .16-2.0 .175 2.5 .19 3.0 .20 T a b l e 34 Weekly Feed Consumption of Mink on the Canned R a t i o n s Horse C h i c k e n C h i c k e n Meat Whale Waste A Yfaste B H e r r i n g Week T23T T24T" (19) Tl9) (17) 1 30 cans 38 3 k 32 27 2 35 40 36 40 25 3 36 51 38 52 33 4 33 41 41 52 32 5 34 32 40 42 30 6 34 45 40 42 27 Ave. 37.7 1 2 .05 41.7±6.40 3-82*2.73 43.3*7.66 29.0*2.23 The average w e i g h t of one can of f e e d was 548 gm. The numbers i n b r a c k e t s are t h e number of mink per group. 103 V I I I . 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