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The nutrition of the female pastel mink (Mustela vison) Farrell, David James 1966

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THE NUTRITION OF THE FEMALE PASTEL MINK (Mustela v l s o n )  by DAVID JAMES FARRELL Diploma i n A g r i c u l t u r e , The R o y a l A g r i c u l t u r a l Cirencester, B.S.A., U n i v e r s i t y  England,  1954  o f B r i t i s h Columbia, 1964  A T h e s i s Submitted  i n Partial  Fulfilment  of the Requirements f o r the Degree o f  MASTER OF SCIENCE IN AGRICULTURE i n the D i v i s i o n o f Animal 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 conforming standard r e q u i r e d  College,  t o the  from c a n d i d a t e s f o r the  Degree o f Master o f S c i e n c e i n A g r i c u l t u r e  THE UNIVERSITY OF BRITISH COLUMBIA J u l y , 1966  In presenting 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 of the requirements for an advanced degree a t the U n i v e r s i t y of B r i t i s h Columbia, I agree that 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 reference and study.  I f u r t h e r agree that permission., f o r extensive  copying of 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 granted by the Head of my Department or by h i s representatives.  I t i s understood that copying  or 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 gain s h a l l not be allowed without my w r i t t e n permission.  Department of  ^UtA^a£  </c •  The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8 , Canada  ABSTRACT A s t u d y , comprised o f f i v e p a r t s , has been p a r r i e d out on seven a d u l t , f e m a l e , p a s t e l mink.  M e t a b o l i c r e s p o n s e s t o ambient  temperature have shown t h a t t h e s e mink cannot t o l e r a t e t e m p e r a t u r e s much above 29°C, but a r e n o t unduly d i s t u r b e d by low temperatures around 0 ° C  Under s l e e p i n g c o n d i t i o n s , and w i t h i n t h e i r t h e r m a l  n e u t r a l zone (25_2 C) , the t h r e e a n i m a l s measured d i d n o t  demonstrate  an a b n o r m a l l y h i g h m e t a b o l i c r a t e . Under c o n d i t i o n s p f p r o l o n g e d f a s t , t h e s e mink appeared t o m a i n t a i n normal a c t i v i t y , a l t h o u g h they l o s t much bodyweight. The a p p a r e n t l y h i g h , d a i l y , u r i n a r y , n i t r o g e n e x c r e t i o n , when r e l a t e d t o h e a t p r o d u c t i o n , gave a v a l u e of 2.5 mg o f u r i n a r y n i t r o g e n per C a l o r i e  (A.D.E.).  The e f f e c t o f a d d i t i o n s o f f i b r e t o a b a s a l r a t i o n has shown an i n v e r s e r e l a t i o n s h i p between t h i s component and t h e t i m e o f passage o f the f e e d .  The apparent d i g e s t i b i l i t y o f the ash  component i n the r a t i o n was markedly d e c r e a s e d w i t h i n c r e a s i n g i n c r e m e n t s of d i e t a r y f i b r e , b u t t h a t o f the f a t was o n l y v e r y s l i g h t l y reduced.  Under t h e s e e x p e r i m e n t a l c o n d i t i o n s , n i t r o g e n  r e t e n t i o n appears t o be always p o s i t i v e , p o s s i b l y r e f l e c t i n g a c o n s t a n t demand f o r f u r growth, and a c o n s t a n t l o s s o f n i t r o g e n i n the form o f ammonia. Maintenance energy (A.D.E.) r e q u i r e m e n t s of t h e s e mink have been q u a n t i t a t e d .  The e f f e c t s o f a d e c r e a s e i n cage c a p a c i t y  and the a d d i t i o n s o f f i b r e t o the r a t i o n appear animal's energy r e q u i r e m e n t s .  t o decrease the  The C a l o r i c i n t a k e o f a one kg  mink i s almost i d e n t i c a l t o t h a t suggested by t h e N.R.C. Water i n t a k e , when r e l a t e d t o energy appreciably  (A.D.E.), i s  l e s s than the 1 gm / C a l o r i e o f heat  g e n e r a l l y a c c e p t e d f o r mammals.  produced  However, i t i s i n c l o s e  ment w i t h f i g u r e s o b t a i n e d f o r the c a t and f o r the mouse.  agreeThe  a d d i t i o n o f a n o n - n u t r i t i v e b u l k t o the r a t i o n s i g n i f i c a n t l y increases ration.  the water i n t a k e when r e l a t e d t o the A.D.E. o f the  iv  TABLE OF CONTENTS Page ABSTRACT  v  TABLE OF CONTENTS  •..  i i iv  LIST OF TABLES  v i i  LIST OF FIGURES  viii  ACKNOWLEDGEMENTS .  x  INTRODUCTION  • , .  1  PART I - THE METABOLIC RATE OF THE MINK Introduction  3  . . . . . . . .  3  Experimental  3  Animals Apparatus Acclimation Metabolic determinations  4 4 4 4  R e s u l t s and D i s c u s s i o n ; . . A. M e t a b o l i c Rate i n R e l a t i o n t o Ambient Temperature . . . . . . . . . . . B. B a s a l Metabolism  5 5 9  Bibliography  14  PART I I - STUDIES ON THE MINK DURING STARVATipN  16  Introduction  •  Experimental  16  Animals Housing Data C o l l e c t i o n . . . . . Chemical A n a l y s i s Results  , • . . . . . . . . . . . . . ,  16 16 17 17 18  Discussion Bibliography  16  23 . . . . .  28  V  TABLE OF CONTENTS  (cont'd) Page  PART I I I - THE EFFECT OF THE ADDITION OF FIBRE TO THE RATION  30  Introduction Experimental  . . . ."  .  and D i s c u s s i o n Time o f Passage Apparent D i g e s t i b i l i t y Nitrogen Retained  31 31 31 34 34  General Animals A n a l y t i c a l Methods Time o f Passage S t u d i e s Results 1. 2. 3.  30  . . . . . .  35 35 35 38 42  Bibliography  44  PART IV - ENERGY REQUIREMENTS FOR MAINTENANCE Introduction  44  Experimental  46 46 46 46 46 47  Animals and Treatment Rations . . . . Housing S p e c i a l Equipment Data C o l l e c t i o n Results  48  Discussion  55  Bibliography  60  PART V - WATER REQUIREMENTS FOR MAINTENANCE Introduction Experimental S p e c i a l Equipment Feed M o i s t u r e M e t a b o l i c Water Results  . . . . . . . . . . . .  63 63 64 64 64 64 65  vi  TABLE OF CONTENTS (cont'd) Page Discussion Bibliography  . , . .  65 71  APPENDICES I II III IV  An I n d i r e c t A n i m a l C a l o r i m e t e r  73  Mink C e r e a l G r a i n P e l l e t s  78  I n d i v i d u a l Weight Records (grams) o f C o n t r o l s . .  79  I n d i v i d u a l Weekly Weight Records (grams)  80  V  I n d i v i d u a l D a i l y Feed I n t a k e Records (grams)  VI  D a i l y Feed ( d r y ) I n t a k e and Mean Body Weight of Mink D u r i n g D i g e s t i b i l i t y T r i a l s i n M e t a b o l i s m Cages  85  Mean Net D a i l y Water I n t a k e f o r Each Mink (grams)  86  I n d i v i d u a l Weekly Weigh-back o f Feed (grams)  , .  87  Mean D a i l y U r i n e Volume Voided by Mink Housed i n M e t a b o l i s m Cages and Measured D u r i n g S t a r v a t i o n and D i g e s t i b i l i t y T r i a l s . , . .  88  VII VIII IX  . .  81  vii  LIST OF TABLES TABLE  Page PART I :  I  THE METABOLIC RATE OF THE MINK  The r e s p i r a t i o n r a t e of mink no. P7 r e c o r d e d metabolism t r i a l s  II III  a t v a r i o u s ambient temperatures  Measurements o f the b a s a l m e t a b o l i c Heat p r o d u c t i o n  II  III  IV  . . .  r a t e o f t h r e e mink  8 10  of f a s t i n g a d u l t mink  PART I I : STUDIES ON THE MINK DURING I  during  12 STARVATION  The mean d a i l y f a e c a l e x c r e t i o n , and i t s from mink f a s t e d  composition 19  D a i l y l o s s i n body weight of t h r e e f a s t e d mink d u r i n g January  20  The d a i l y n i t r o g e n e x c r e t i o n o f f a s t e d mink d u r i n g September and January  22  The r e l a t i o n s h i p between the heat p r o d u c t i o n q f an u n t r a i n e d f a s t e d mink i n the r e s p i r o m e t e r and the animal's c a l c u l a t e d b a s a l metabolism r a t e .  25  PART I I I : . THE ...EFFECT OF. THE -ADDITION OF FIBRE TO THE RATION I  II  III  IV  The c o m p o s i t i o n basis  o f the b a s a l r a t i o n on an "as mixed"  Composition and mean r e s u l t s of a n a l y s e s d i e t s used  32 o f the .  33  Time (minutes) r e q u i r e d f o r a marked feed t o appear i n the f a e c e s o f female p a s t e l mink on d i e t s c o n t a i n i n g various fibre levels  35  The apparent n i t r o g e n r e t a i n e d by female p a s t e l mink d u r i n g metabolism s t u d i e s , .  39  viii  LIST OF FIGURES FIGURE  Page PART I :  1  2  THE METABOLIC RATE OF THE MINK  The r e l a t i o n s h i p between r a t e of oxygen and ambient temperature f o r mink no. P7  consumption  The r e l a t i o n s h i p between r a t e of oxygen and ambient temperature f o r mink no. P5  consumption  PART I I I : 1  2  3  4  ENERGY REQUIREMENTS FOR  36  MAINTENANCE  The r e l a t i o n s h i p between the apparent d i g e s t i b l e energy i n t a k e and the body weight o f a l l mink on a l l f o u r r a t i o n s and housed i n ranch-type cages . . . . . . . .  49  The r e l a t i o n s h i p between the apparent d i g e s t i b l e energy i n t a k e and the body weight o f those mink which showed no weight change and were housed i n ranch-type cages and m a i n t a i n e d on the b a s a l r a t i o n  50  The r e l a t i o n s h i p between the apparent d i g e s t i b l e energy i n t a k e and the body weight of mink r e c e i v i n g the b a s a l r a t i o n and housed i n metabolism cages  51  A diagrammatic r e p r e s e n t a t i o n o f the apparent d i g e s t i b l e energy i n t a k e o f each i n d i v i d u a l mink on the f o u r r a t i o n s and of t h e i r weight changes w h i l e on the rations  54  PART V: 1  7  THE EFFECT OF THE ADDITION OF FIBRE TO THE RATION  The apparent d i g e s t i b i l i t y of the f a t , p r o t e i n , ash and complete r a t i o n s as a f f e c t e d by f i b r e l e v e l i n the r a t i o n PART IV:  1  6  WATER REQUIREMENTS FOR  MAINTENANCE  The r e l a t i o n s h i p between t o t a l water and apparent d i g e s t i b l e energy i n t a k e of mink r e c e i v i n g the b a s a l r a t i o n and housed i n r a n c h - s t y l e cages  66  ix  LIST OF FIGURES (cont'd) FIGURE 2  3  Page The r e l a t i o n s h i p between water i n t a k e and body weight o f mink r e c e i v i n g the b a s a l r a t i o n and housed i n r a n c h - s t y l e cages  67  The r e l a t i o n s h i p between water i n t a k e and body weight o f mink r e c e i v i n g the b a s a l r a t i o n , housed i n r a n c h - s t y l e cages, and demonstrating weight s t a s i s  68  APPENDIX 1  A diagrammatic r e p r e s e n t a t i o n o f the r e s p i r o m e t e r  . .  74  X  ACKNOWLEDGEMENTS  I w i s h t o thank D r . B.A. E a g l e s , Dean o f t h e F a c u l t y o f A g r i c u l t u r e and Chairman o f t h e D i v i s i o n o f A n i m a l S c i e n c e , f o r his  p e r m i s s i o n t o undertake t h i s p r o j e c t and f o r t h e use o f t h e  required f a c i l i t i e s .  A l s o my thanks a r e extended  t o those a t t h e  U n i v e r s i t y o f V i c t o r i a who p e r m i t t e d t h e c o m p l e t i o n o f t h i s s t u d y at  that i n s t i t u t i o n . To D r . A . J . Wood, Dean o f A r t s and S c i e n c e a t t h e  U n i v e r s i t y of V i c t o r i a (formerly P r o f e s s o r of Animal Science a t the U n i v e r s i t y o f B r i t i s h Columbia) I w i s h t o e x p r e s s my s i n c e r e thanks for of  h i s i n t e r e s t , encouragement and guidance throughout t h e c o u r s e t h i s study. F i n a l l y , the author i s s i n c e r e l y g r a t e f u l t o h i s w i f e ,  P e a r l , whose s a c r i f i c e s and encouragement have made t h e s e y e a r s o f graduate s t u d y p o s s i b l e .  INTRODUCTION  INTRODUCTION  ".... the p r a c t i c a l problems of meeting the n u t r i t i o n a l needs of s t o c k are major i n l i v e s t o c k husbandry. At the o u t s e t i t i s important to r e a l i z e the c e n t r a l and o v e r r i d i n g importance of energy i n any c o n s i d e r a t i o n of n u t r i t i o n . " K.L.  The  general  l a c k of p r e c i s e i n f o r m a t i o n  Blaxter  on b a s i c  nutritional  requirements of the mink i s becoming more apparent w i t h the demands of the i n d u s t r y to reduce feed c o s t s . mink r e s e a r c h  has  w i t h another and q u a l i t y and  centred  To date,, the m a j o r i t y  around the replacement of one  the r e c o r d i n g  of the r e s u l t s o b t a i n e d  growth r a t e performance.  The  of  r a t i o n ingredient i n terms of p e l t  f a i l u r e to provide  i n d u s t r y w i t h a dry s y n t h e t i c d i e t on which an animal can reproduce and  increasing  the mink  grow,  l a c t a t e , i s e v i d e n c e enough t h a t t h i s r a p i d l y growing  i n d u s t r y i s i n need of a more fundamental approach to i t s r e s e a r c h problems. Because much of the f i n a n c i a l support f o r mink r e s e a r c h been p r o v i d e d  by  the feed I n d u s t r y  t h a t the r e s u l t s must be  immediate.  the mink i n d u s t r y c o n c e r n - p e l t  to mention but  healthy four. .  the mink i n d u s t r y , i t f o l l o w s  of such a n a t u r e t h a t t h e i r a p p l i c a t i o n s to  p r a c t i s e be both obvious and  of a p p a r e n t l y  and  has  q u a l i t y , k i d n e y damage, the sudden deaths  a n i m a l s , and I t may  Some c u r r e n t problems f a c i n g  be  the f a i l u r e of females to l a c t a t e ,  of some importance to re-examine  n u t r i e n t requirements of t h i s s p e c i e s , b e a r i n g  the  i n mind the e f f e c t s of  2  other r a t i o n components on the a b s o r p t i o n implications  of h i g h energy r a t i o n s , and  the a v a i l a b i l i t y and  destruction  of these n u t r i e n t s ,  the  the e f f e c t s of s t o r a g e  on  of these n u t r i e n t s p r e s e n t i n animal  proteins. I t i s the o b j e c t  of t h i s t h e s i s to study i n t e n s i v e l y a  mink under c l e a r l y d e f i n e d growth or r e p r o d u c t i v e but  they may  conditions,  stresses.  The  be siuch t h a t o t h e r s can  uncomplicated by f i n a l r e s u l t s may  few  appreciable not be  startling  study c e r t a i n i n t e r e s t i n g a s p e c t s  i n more depth. Some of t h i s s u b j e c t applicable  to the  operation  matter under c o n s i d e r a t i o n  may  of an a g r i c u l t u r a l e n t e r p r i s e .  not But  be such  a p p a r e n t l y i m p r a c t i c a l i n v e s t i g a t i o n s are extremely important because they  "have d i g n i f i e d the c a l l i n g of a g r i c u l t u r e and have g i v e n the farmer an i n t e l l e c t u a l background and b a s i s f o r h i s t h i n k i n g t h a t cannot be e a s i l y measured." F.B.  Mumford.  THE NUTRITION OF THE FEMALE PASTEL MINK (Mustela  PART  I:  THE METABOLIC RATE OF THE MINK  vison)  3  INTRODUCTION  B a s a l metabolism v a l u e s lishing  serve as a u s e f u l b a s e l i n e i n e s t a b -  the energy requirements of a s p e c i e s f o r maintenance and  production  (2, 5, 7, 8 ) .  The main o b j e c t of t h i s study has been to  measure the b a s a l m e t a b o l i c  r a t e of the mink.  Relatively l i t t l e  i n f o r m a t i o n i s a v a i l a b l e on the heat p r o d u c t i o n  of f u r b e a r i n g  (11, 12).  f o r the heat  R u s s i a n workers have r e p o r t e d v a l u e s  of a d u l t s i l v e r foxes  for  (13) and  of mink  animals  production  (10).  EXPERIMENTAL  The  energy metabolism of an animal may  l e v e l by removing those production; stimulus  i n f l u e n c e s t h a t tend to i n c r e a s e i t s heat  i n p a r t i c u l a r , the i n f l u e n c e of f e e d , a c t i v i t y and  of heat or c o l d .  For the purposes of t h i s study,  c o n d i t i o n s were e s t a b l i s h e d f o r the m e t a b o l i c 1.  be reduced to a minimum  The b a s a l m e t a b o l i c l e s s than f i v e and  the f o l l o w i n g  r a t e measurements:  r a t e measurements commenced not one h a l f hours a f t e r f e e d i n g .  of passage s t u d i e s had  Time  shown t h a t the mink becomes p o s t -  a b s o r p t i v e about f i v e hours a f t e r the i n g e s t i o n of i t s last 2.  The  feed. animal was  Observations  i n a s t a t e of complete r e s t .  had  shown t h a t a s t a t e of complete r e s t  i n the mink can o n l y be assured  i n the n a t u r a l l y  sleeping, s t a t e ; hence a l l measurements have been made w i t h animals  asleep.  the  4  3.  The a n i m a l was w i t h i n i t s t h e r m o n e u t r a l  zone.  Animals Two female p a s t e l r a n c h mink s e l e c t e d from a group o f s i x animals  (3) were used t o determine  and the b a s a l m e t a b o l i c r a t e .  b o t h t h e zone o f t h e r m o n e u t r a l i t y  A t h i r d mink from t h e same group was  s e l e c t e d f o r t h e d e t e r m i n a t i o n o f b a s a l metabolism  only.  Apparatus The apparatus  used f o r m e t a b o l i c r a t e measurements was an  i n d i r e c t , c l o s e d c i r c u i t respirometer„  A d e s c r i p t i o n o f t h e apparatus  and i t s o p e r a t i o n appears i n Appendix I . Acclimation Because t h e mink becomes h y p e r a c t i v e f o r p r o l o n g e d  periods  when p l a c e d i n a c o n f i n e d space and i n u n f a m i l i a r s u r r o u n d i n g s , i t was f i r s t n e c e s s a r y t o t r a i n t h e a n i m a l s f o r p e r i o d s up t o f o u r weeks to accept t h e environment o f t h e r e s p i r o m e t e r (Appendix any m e t a b o l i c  I) prior to  trials.  Metabolic determinations A l l t r i a l s were c a r r i e d out between 1400 and 1700 hours„ E x t e n s i v e o b s e r v a t i o n s showed t h i s t o be t h e p e r i o d o f m i n i m a l a c t i v i t y A t the o u t s e t i t was n e c e s s a r y of t h i s s p e c i e s .  t o a s c e r t a i n t h e t h e r m a l n e u t r a l zone  D u r i n g these d e t e r m i n a t i o n s , t h e mink had c o n t i n u o u s  a c c e s s t o t h e i r normal f e e d .  The a n i m a l s were a s l e e p d u r i n g t h e  0  5  p e r i o d of measurement.  The mink might t h e r e f o r e be c o n s i d e r e d  to  be  i n the r e s t i n g s t a t e (2) r a t h e r than i n the b a s a l s t a t e .  RESULTS AND  DISCUSSION  A. M e t a b o l i c Rate i n R e l a t i o n to Ambient The  Temperature  response of the mink, i n terms of oxygen consumption, to  changes i n ambient temperature i s i l l u s t r a t e d The  equations  f o r the near l i n e a r p o r t i o n s of these  u s i n g the method of l e a s t squares. oxygen consumption changed 1.00 f o r mink No.  P5  consumption was f o r mink No. two  i n F i g u r e 1 and  P5.  Over t h i s temperature range,  v a l u e was  0.92.  40.4cc02/gm/24hr f o r mink No.  P7,  At 0°C and  P7,  significantly different  the oxygen  41.4cc02/gm/24hr the  (F=.05).  I t seems s a f e to conclude t h a t b a s a l m e t a b o l i c  r a t e can  determined w i t h i n the thermal n e u t r a l zone shown i n F i g u r e 1 F i g u r e 2.  the  and  A t e s t of s i g n i f i c a n c e shows t h a t the s l o p e s of  response l i n e s are not  2.  l i n e s were c a l c u l a t e d  cc/gm/24hr/°C f o r mink No.  the c o r r e s p o n d i n g  Figure  be  and  With the a v a i l a b l e i n s t r u m e n t a l procedures i t i s not p o s s i b l e  to measure, m e t a b o l i c  r a t e w i t h s u f f i c i e n t p r e c i s i o n to d e l i n e a t e a  c r i t i c a l thermal n e u t r a l p o i n t . uptake i s r e l a t i v e l y constant r e s p i r a t o r y r a t e f o r one observation.  F o r example, i n the case of P7,  between 17 and  27°C.  The  r e c o r d of  of the mink (Table I) agrees w i t h  this  oxygen the  6  \  FIGURE  1:  THE RELATIONSHIP BETWEEN RATE OF OXYGEN CONSUMPTION AND AMBIENT TEMPERATURE FOR MINK NO. P7  40  FIGURE 2 : THE RELATIONSHIP BETWEEN RATE OF OXYGEN CONSUMPTION AND AMBIENT TEMPERATURE FOR MINK NO. P5  TABLE I ; THE RESPIRATION RATE OF MINK NO. P7 RECORDED DURING METABOLISM TRIALS AT VARIOUS AMBIENT TEMPERATURES  Temperature TC)  R e s p i r a t i o n Rate (Respirations/Min)  16.2 18.5 22.6 24.2 26.1 29.0  21 21 21 19 20 21  Subsequent measurements of Basal Metabolic rate were c a r r i e d out at a temperature of 25±2°C. E x t r a p o l a t i o n of the l i n e a r p o r t i o n of the temperature response l i n e does not i n t e r c e p t the abscissa p r e c i s e l y at predicted normal body temperature.  This departure i s not unexpected since the  determinations were c a r r i e d out over an extended period of time; hence, some f l u c t u a t i o n : i n the body weight of the mink was unavoidable, and as stated the animals were i n the r e s t i n g rather than i n the basal state. A close observation of both animals during thermal adjustment t r i a l s showed that the mink has e x c e l l e n t powers of thermoregulation. At very low temperatures the mink takes the shape of a b a l l and with increasing ambient temperatures slowly unfolds.  Mink No. P5 appeared  more r e l u c t a n t to regulate by changing body shape than d i d mink No. P7, Measurements could not be c a r r i e d out on e i t h e r animal at temperatures  9  above 29°C.  Both animals became r e s t l e s s and the r e q u i r e d  sleeping  c o n d i t i o n c o u l d not be a t t a i n e d f o r a s u f f i c i e n t l e n g t h of time. I t would appear,  t h e r e f o r e , t h a t under p r a c t i c a l ranch c o n d i t i o n s  an ambient temperature  approaching 29°C s h o u l d be avoided when  c o n d i t i o n s of h i g h h u m i d i t y e x i s t . of about  On the o t h e r hand, a  2°C d i d not unduly d i s t u r b e i t h e r  temperature  animal.  B. B a s a l Metabolism B a s a l heat p r o d u c t i o n per u n i t of body weight  i n mature  animals of d i f f e r e n t s p e c i e s decreases r a p i d l y w i t h i n c r e a s i n g body weight, but remains surface area.  r e l a t i v e l y c o n s t a n t when expressed per u n i t of  The l a t t e r parameter  is difficult  to measure w i t h any  degree of p r e c i s i o n and f o r t h i s r e a s o n i s not a good r e f e r e n c e base ( 2 ) . Kleiber  On the b a s i s of i n t e r s p e c i e s comparisons,  Brody  (5) have f o r m u l a t e d e q u a t i o n s r e l a t i n g body weight  heat production,,  (2) and to b a s a l  At the p r e s e n t time, t h e r e are i n s u f f i c i e n t d a t a t o  suggest t h a t i n t r a and i n t e r s p e c i f i c r e l a t i o n s of body s i z e m e t a b o l i c r a t e are the same. r e p r e s e n t e d metabolism  Lee  and  (6) r e p o r t e d t h a t a l i n e a r e q u a t i o n  d a t a on r a b b i t s as w e l l as a power f u n c t i o n .  Haywood (4) found t h a t the b a s a l m e t a b o l i c r a t e of the genus Peromyscus does not d i f f e r from Brody's  i n t e r s p e c i e s approximation.  However, w i t h i n r a c e s of the genus, the weight 0.54  and 0.94.  Some of t h i s v a r i a t i o n was  i n t i s s u e metabolism  exponents  (2) ranged between  a t t r i b u t e d to d i f f e r e n c e s  a r i s i n g from d i f f e r e n c e s between i n d i v i d u a l s  10  TABLE I I : MEASUREMENTS OF THE BASAL METABOLIC RATE OF THREE MINK  No, o f Trials  Body Weight Kg  Cal/Kg BW * /24hr 1  Cal/24hr  0  Cal/Kg BW' /24hr  73  Cal/Kg BW' /24hr  Mink No. P7 3 1 3 Mean  . 0.655 0.640 0.633  52.4 53.4 60.9  80.0 83.4 91.8  71.5 74.5 82.4  72.0 74.7 83.1  0.653  55.6  85.1  76.1  76.6  Mink No. P5 3 2 2 3 Mean  0.656 0.648 0.670 0.692  57.4 56.3 49.2 58.5  87.5 86.9 73.4 84.5  78.2 77.4 64.7 76.6  78.8 78„3 66.5 77.3  0.667  55.4  83.1  74.3  75.2  Mink No. P3 2 4 6 3 Mean  0.795 0.790 0.785 0.781  66.3 61.2 68.5 68.3  83.3 77.5 87.3 87_A  77.4 72.7 79.1 79J5  78.7 73.0 82.1 82.3  0.788  66.1  83.9  77.2  79.0  84.0  75.9  76.9  Mean o f a l l Measurements  75  i n the c o m p o s i t i o n of the p h y s i o l o g i c a l l y a c t i v e body mass.  Haywood's  h y p o t h e s i s i s not i n agreement w i t h work c i t e d by B l a x t e r ( 1 ) . For comparative  purposes,  the d a t a p r e s e n t e d i n T a b l e I I  has been c a l c u l a t e d by r a i s i n g body weight t o three d i f f e r e n t power functions. Each b a s a l m e t a b o l i c r a t e used  i n the p r e p a r a t i o n of the  t a b l e i s the mean of a number of d e t e r m i n a t i o n s , each of which of not l e s s than t e n minutes d u r a t i o n when the mink was be i n the s t a t e d e f i n e d as b a s a l a t the o u t s e t .  was  observed  These r e s u l t s  to  suggest  t h a t the b a s a l m e t a b o l i c r a t e of the s l e e p i n g , c o n d i t i o n e d mink i s not abnormally  high.  The v a l u e s o b t a i n e d are s l i g h t l y h i g h e r than would  be p r e d i c t e d by the r e g r e s s i o n e q u a t i o n s proposed  by K l e i b e r  (5)  and  f i g u r e s r a n g i n g from 111.0  to  Brody ( 2 ) . Oldfield 250  Cal/kg  1 , 0  /24hr  d i f f i c u l t y was  (9) o b t a i n e d average f o r t h r e e mink.  encountered  t h a t a c e r t a i n amount of  i n m a i n t a i n i n g a q u i e s c e n t s t a t e i n the  animals a f t e r a 24 hour f a s t . lower  He noted  The p r e s e n t f i n d i n g s a r e c o n s i d e r a b l y  than those r e p o r t e d by P e r e l ' d i k and T i t o v a ( 6 ) .  are p r e s e n t e d i n summary form i n T a b l e I I I .  These r e s u l t s  12  TABLE I I I ;  HEAT PRODUCTION OF FASTING ADULT MINK ( P e r l e ' d i k & T l t o v a , 1950)  D a i l y Heat P r o d u c t i o n , K C a l Per Kg Body Weight  Season  Per Sq. M.. o f S u r f a c e Area  140 149 170 151 129 150  January, February March, A p r i l May, J u l y August, October November, December Mean f o r Year  1748 1840 2001 1778 1627 1815  U n f o r t u n a t e l y , a c c e s s t o t h e i r o r i g i n a l paper was n o t p o s s i b l e . The apparent  s e a s o n a l f l u c t u a t i o n s i n the heat p r o d u c t i o n appear t o  f o l l o w c l o s e l y the s e a s o n a l p r o d u c t i v i t y o f the mink, as w e l l as changes i n p h y s i o l o g i c a l l y a c t i v e body mass. not r e p r e s e n t t r u e b a s a l v a l u e s .  F o r these r e a s o n s , the data may  Scholander  ( 1 1 ) , i n h i s study on  A r c t i c mammals, found t h a t one of the few mammals which had a d e v i a t i o n of g r e a t e r than 20% i n b a s a l m e t a b o l i c r a t e from Brody's i n t e r s p e c i e s equations was the A r c t i c Weasel (Mustela r i x o s a ) . d a t a on two weasels the s t a n d a r d c u r v e . weasels weight  However, s i m i l a r  from W i s c o n s i n showed o n l y a s l i g h t e l e v a t i o n above The b a s a l m e t a b o l i c r a t e o f one o f Scholander's  compared w i t h the other was g r e a t l y e l e v a t e d , and the body o f these A r c t i c weasels  immature.  i n d i c a t e d t h a t they were p r o b a b l y  The B.M.R„/24hr f o r one weasel was 31 C a l a t 70 gm, the  other 29 C a l a t 38 gm„  When the data,are transformed  t o body  weight  13  the  heat p r o d u c t i o n becomes 228 Cal/Kg/24hr and 333 Cal/Kg/24hr  respectively. Because of the numbers of mink i n v o l v e d i n these b a s a l m e t a b o l i c r a t e d e t e r m i n a t i o n s and because of t h e i r narrow weight range, i t has not been p o s s i b l e to f o r m u l a t e an e q u a t i o n r e l a t i n g  b a s a l heat  p r o d u c t i o n t o body weight i n the mink as was done i n the cases of the interspecific  comparisons mentioned  previously.  14  BIBLIOGRAPHY  1.  B l a x t e r , L.K. 1962. The energy metabolism H u t c h i n s o n and Co., London.  2.  Brody, S. 1945. New York.  3.  F a r r e l l , D.J. 1966. P a r t IV. Energy requirements f o r maintenance. (Included i n t h i s t h e s i s )  4.  Haywood, J.S. 1965. M e t a b o l i c r a t e and i t s temperature - a d a p t i v e s i g n i f i c a n c e i n s i x geographic r a c e s of Peromyscus. Can. J . Zoo. 43, 309-323.  5.  K l e i b e r , M.  6.  Lee, R.C. 1939. S i z e and b a s a l metabolism J . N u t r i t i o n , 18, 489-500.  7.  M i t c h e l l , H.H. L.E. Card, and T.S. Hamilton. 1931. study of the growth of White l e g h o r n c h i c k e n s . Agr. Expt. S t a . B u l l . No. 376, 83-139.  8.  M o r r i s o n , F.B. 1959. Feeds and f e e d i n g . 22nd. ed., M o r r i s o n P u b l i s h i n g Co., C l i n t o n , Iowa.  9.  O l d f i e l d , J.E. 1949. A study of n i t r o g e n metabolism w i t h s p e c i a l r e f e r e n c e t o mink. Unpublished Master's T h e s i s , Dept. of Animal S c i . , U n i v e r s i t y of B r i t i s h Columbia.  1961.  B i o e n e r g e t i c s and growth.  The F i r e of L i f e .  of ruminants.  R e i n h o l d Pub.  W i l e y and Sons. of the a d u l t  New  Corp.,  York.  rabbit.  A technical Illinois  10.  P e r e l ' d i k , M.N. and M.I. T i t o v a . 1950. (Experimental d e t e r m i n a t i o n o f f e e d i n g standards f o r a d u l t b r e e d i n g mink.) K a r a k u l . Zver., _3_, No. 2, 29. (Quoted by A i t k e n , F.C. 1963 i n F e e d i n g of f u r - b e a r i n g a n i m a l s . T e c h n i c a l Communication No. 23, Commonwealth Bureau of Animal N u t r i t i o n , Aberdeen.)  11.  S c h o l a n d e r , P.F. 1950 a. R.-Hock, V. W a l t e r s , and L. I r v i n g . A d a p t a t i o n to c o l d i n a r c t i c and t r o p i c a l mammals and b i r d s i n r e l a t i o n to body temperature, i n s u l a t i o n and basal metabolic r a t e . B i o l . B u l l . £ 9 , 237-258.  15  12.  Scholander, P.F. 1950 b. V. W a l t e r s , R. Hock and L. I r v i n g . Body i n s u l a t i o n of some a r c t i c and t r o p i c a l mammals and birds. B i o l . B u l l . 99, 237-258.  13.  T i t o v a , M.I. 1950. ( I n f l u e n c e of l e n g t h of d a y l i g h t on b a s a l m e t a b o l i c r a t e i n s i l v e r foxes.) K a r a k u l . Zver., _3, No. 3, 55. (Quoted by A i t k e n , F.C. 1963 i n Feeding of f u r - b e a r i n g a n i m a l s . T e c h n i c a l Communication No. 23, Commonwealth Bureau of Animal N u t r i t i o n , Aberdeen.)  THE NUTRITION OF THE FEMALE PASTEL MINK (Mustela  PART I I :  STUDIES ON THE MINK DURING STARVATION  vison)  INTRODUCTION  I t i s common ranch p r a c t i s e , i n p r e p a r a t i o n f o r to r e s t r i c t  the feed i n t a k e of the mink i n o r d e r to induce  body weight.  Because the mink has  time (10, 18,  t r a c t and  a loss i n  T h i s leads to the consumption of the d a i l y feed  i n a few h o u r s . transit  breeding,  20,  26)  offering  an e x c e p t i o n a l l y r a p i d feed  i t w i l l r a p i d l y evacuate i t s d i g e s t i v e  i n so doing e n t e r s a s t a t e of endogenous c a t a b o l i s m .  i s of i n t e r e s t , t h e r e f o r e , to study  the metabolism of t h i s  It  species  under such c o n d i t i o n s , p a r t i c u l a r l y i t s endogenous e x c r e t i o n s . d a t a has been p u b l i s h e d on the e f f e c t s of s t a r v a t i o n on man on the dog  (13), on the r a t ( 2 ) , and  but much of i t may  Much  (3, 4 ) ,  on other domestic s p e c i e s  (13)  not be r e l e v a n t to the s m a l l c a r n i v o r e .  EXPERIMENTAL  Animals F i v e a d u l t female p a s t e l mink, s e l e c t e d from a group of seven animals  (10), were used i n two  s e r i e s of t r i a l s c a r r i e d out f o r a  p e r i o d of f i v e days i n September, and January. ration  f o r t h r e e days i n the f o l l o w i n g  P r i o r to t h i s experiment, the animals were f e d a b a s a l  (10).  Water was  provided  ad l i b i t u m i n c o n v e n t i o n a l water cups.  Housing The metabolism room was and  adequately  l i g h t e d and v e n t i l a t e d ,  s u b j e c t to the p r e v a i l i n g o u t s i d e e n v i r o n m e n t a l temperatures.  17  The mink were housed i n mesh w i r e ,  galvanized, rectangular  cages  measuring 43 cm. i n h e i g h t , 30 cm. i n w i d t h , and 36 cm. i n l e n g t h . The  cages s a t above aluminum f u n n e l s .  A p i e c e of fine-mesh w i r e  s c r e e n was p l a c e d i n the f u n n e l o u t l e t .  A glass cylinder containing  1 ml. of s u l p h u r i c a c i d , p l a c e d beneath the f u n n e l , trapped  the v o i d e d  urine.  Data C o l l e c t i o n The mink were c o n s i d e r e d  to be i n the p o s t a b s o r p t i v e  f i v e and one h a l f hours f o l l o w i n g the removal of f e e d .  Animals were  weighed a t t h i s time and a g a i n a t the end of the e x p e r i m e n t a l During  the l a t e r t r i a l s , The  state  period.  the animals were weighed d a i l y .  volume of the u r i n e was r e c o r d e d  following  decantation  of the u r i n e from the c y l i n d e r s , which were then washed s e v e r a l times w i t h d i s t i l l e d water, the washings b e i n g added t o the c o l l e c t e d u r i n e .  Chemical A n a l y s i s The m e t a b o l i c  f a e c e s were c a r e f u l l y scraped  o f f the f u n n e l  and p l a c e d i n a p r e v i o u s l y e x t r a c t e d , t a r e d , f a t - e x t r a c t i o n thdanble. The m a t e r i a l was d r i e d a t 100°C t o a constant weight, then e x t r a c t e d for  16 hours w i t h petroleum e t h e r The  and  pestle.  (30-60°C b o i l i n g  range).  e x t r a c t e d r e s i d u e was ground to a powder w i t h a mortar Representative  d u p l i c a t e samples were analyzed f o r  n i t r o g e n , u s i n g a m i c r o - k j e l d a h l procedure. as a c a t a l y s t .  Mercuric  oxide was used  Ash was determined by h e a t i n g d u p l i c a t e samples a t  600°C f o r twelve h o u r s .  18  F o l l o w i n g the removal o f a l l f a e c a l m a t t e r , the aluminum f u n n e l s were r i n s e d s e v e r a l times w i t h h o t d i s t i l l e d water, washings b e i n g added t o the v o i d e d u r i n e . to  Every p r e c a u t i o n was taken  a v o i d c o n t a m i n a t i o n o f the f a e c e s w i t h u r i n e .  The t o t a l u r i n e  c o l l e c t i o n was f i l t e r e d under vacuum through a No. 1 Whatman paper.  these  filter-  The t o t a l volume o f the f i l t r a t e was r e c o r d e d and d u p l i c a t e  a l i q u o t s were assayed f o r n i t r o g e n u s i n g a m i c r o - k j e l d a h l p r o c e d u r e .  RESULTS  The mean d a i l y q u a n t i t y and c o m p o s i t i o n o f the endogenous f a e c e s , t o g e t h e r w i t h the mean d a i l y weight presented i n Table I .  l o s s o f each a n i m a l , i s  The low e t h e r e x t r a c t and the h i g h p r o t e i n  c o n t e n t may be worthy o f note i n t h a t they d i f f e r t h a t r e p o r t e d f o r the young c a l f  a p p r e c i a b l y from  (6) and f o r man ( 8 ) .  Reflecting  these  d i f f e r e n c e s i n c o m p o s i t i o n , t h e c a l c u l a t e d energy content o f the faeces i s a p p r o x i m a t e l y 4.9 C a l o r i e s p e r gm and i s lower than v a l u e s c i t e d by McKenzie (15) f o r o t h e r s p e c i e s .  The d a i l y mean weight  loss  was 41.0 gm f o r the mink i n the September t r i a l and 44.1 gm f o r those in  the January t r i a l .  h i g h weight  The former f i g u r e i n c l u d e s the e x c e p t i o n a l l y  l o s s o f mink No. P6 which averaged  48.8 gm.  T h i s animal  became i l l d u r i n g the l a t t e r p a r t o f the f a s t i n g p e r i o d and f o r t h i s r e a s o n the d a t a from t h i s animal a r e n o t i n c l u d e d i n the c a l c u l a t i o n s . A post-mortem examination r e v e a l e d t h a t i t was s u f f e r i n g from acute  TABLE I :  Day No  No. o f Animals  Mean Body Weight  THE MEAN DAILY FAECAL EXCRETION, AND ITS COMPOSITION FROM MINK FASTED  Dry M a t t e r Gm/lOOgm Gm Body weight  Proximate a n a l y s i s E x t r a c t P r o t e i n (Nx6.25)  Ether  %  %  Ash  %  Trial  1  3  688  1.263-'  0.184  6.8  60.9  September  2  3  657  1.189  0.181  5.4  55.5  September  3  3  616  0.663  0.108  5.2  60.0  September  4  2  598  0.602  0.100  8.6  54.6  September  5  2  546  0.758  0.139  14.0  44.9  September  1  3  696  1.767  0.394  10.5  54.4  11.0  January  2  3  656  0.849  0.129  6.6  55.7  11.9  January  3  3  614  0.891  0.145  5.4  56.6  10.7  January  20  TABLE I I ;  DAILY LOSS IN BODY WEIGHT OF THREE FASTED MINK DURING JANUARY  Mink N o o  PI  P2  P5  1  2  3  1  2  3  1  2  3  756  718  672  666  623  583  668  628  586  D a i l y Weight Loss (gm)  52  38  46  45  43  40  49  44  43  Weight l o s s as a % o f the mean D a i l y Weight  6.8  5.3  6.8  6.9  6.8  6.8  7.3  7.1  7.3  Day Mean Body Weight (gm)  21  nephritis.  The d a i l y weight l o s s , when expressed  as a p e r c e n t o f  the mean d a i l y body weight f o r the January group (Table I I ) i s remarkably c o n s t a n t  and i s much g r e a t e r than f i g u r e s r e p o r t e d f o r  man, 0.6% (4) and f o r the dog, 0.83% (13) d u r i n g the f i r s t days o f f a s t i n g . obtained  I t i s , however, i n good agreement w i t h  thirty  values  on f a s t i n g w i l d r a t s ( 2 ) , b u t i s g r e a t e r than measurements  on f a s t i n g l a b o r a t o r y r a t s ( 2 ) . s t a r v a t i o n o f these  The t o t a l body weight l o s s e s  two groups o f r a t s was 35.1% and 39.0%, r e s p e c t i v e l y ,  of the s t a r t i n g weight.  These f i g u r e s a r e i n good agreement w i t h a  mean body weight l o s s of 34.6% r e c o r d e d  f o r two mink t h a t d i e d o f  s t a r v a t i o n d u r i n g a v i t a m i n B^ d e f i c i e n c y experiment a t t h i s (unpublished). The  during  laboratory  For the dog, a l o s s o f 62.7% has been r e p o r t e d ( 1 3 ) .  animal s u r v i v e d the f a s t i n g t r i a l .  The p r e s e n t  r e s u l t s would  suggest t h a t the mink has a r e l a t i v e l y h i g h maintenance energy r e q u i r e ment p e r u n i t o f body weight as has been demonstrated i n other Table  studies (11).  I I I r e l a t e s the d a i l y n i t r o g e n l o s s i n the f a e c e s and  in  the u r i n e t o body weight d u r i n g the two t r i a l s .  to  u r i n e volume r a t i o f o r a l l animals was 27 mg/cc.  has been o b t a i n e d when the mink were on f e e d . man (4) has been c a l c u l a t e d t o be 8.3 mg/cc.  The mean n i t r o g e n The same f i g u r e  This r a t i o f o r a f a s t i n g  TABLE I I I : THE DAILY NITROGEN EXCRETION OF FASTED MINK DURING SEPTEMBER AND JANUARY  Day  Body Weight (gm)  Nitrogen Faecal Urinary  Mink No,  Total  Body Weight (gm)  Nitrogen Faeca] U r i n a r y  P4  Faeca]  766  49  216  335  684  111  2  730  134  212  346  646  98  3  694  62  309  371  607  51  432  4  658  66  215  281  568  44  5  622  530  53  214  PI  341  Nitrogen Urinary  Total  Trial  P6  P5  1  Mink No,  Total  Body Weight (gm)  452  613  52  334  386  September  594  57  222  279  September  483  546  63  564  587  September  488  532  (481  15  891  1006)  September  451  504  (432  125  1199  1324)  September  P2  P5  1  756  129  428  557  666  228  395  623  668  105  544  649  January  2  718  103  387  490  623  87  427  514  628  41  517  558  January  3  672  105  513  618  586  100  420  520  586  44  462  506  January  ro  23  DISCUSSION  The marked tendency r a p i d l y i n i t i a l l y , and  of the u r i n a r y n i t r o g e n to f a l l o f f  then to i n c r e a s e on the t h i r d day  i n d i c a t i v e of the d i m i n i s h i n g glycogen r e s e r v e s (12). the i n a b i l i t y  of the adipose  d u r a t i o n without  an apparent  I t also  suggests  t i s s u e t o m a i n t a i n the animal f o r a l o n g increase i n protein catabolism.  r e s e r v e s , a l t h o u g h v i t a l as sources of energy, of  i s probably  Fat  are not always i n d i c a t i v e  s u r v i v a l time, and death o f t e n comes when a p p a r e n t l y adequate f a t  stores s t i l l  exist  (14).  D e s p i t e the s i m i l a r i t y i n the s t a r t i n g weights  of the two  of mink, the c o n s i s t e n t l y h i g h e r n i t r o g e n e x c r e t i o n of the January t o g e t h e r w i t h the i n c r e a s e d body weight l o s s suggests of  l a r g e amounts of p r o t e i n t i s s u e .  the weight l o s s i s 31.5% the September group. f a s t i n g man  the  groups group  degradation  By c a l c u l a t i o n , the c o m p o s i t i o n  p r o t e i n f o r the January  group and  27.3%  of  for  These f i g u r e s are h i g h e r than those r e p o r t e d f o r  (3, 4) and  the f a s t i n g l a b o r a t o r y r a t (2) but are i n agree-  ment w i t h those measured on f a s t i n g w i l d r a t s ( 2 ) . The r e l a t i o n s h i p between the minimal  endogenous u r i n a r y  n i t r o g e n and the b a s a l m e t a b o l i c r a t e i n a wide range of mature  animals  i s , w i t h few e x c e p t i o n s , a f a i r l y c o n s t a n t 2 mg  Calorie  (22).  The  of n i t r o g e n per  t o t a l endogenous n i t r o g e n i s about t w e n t y - f i v e per cent  h i g h e r than t h i s f i g u r e  (22).  I t i s v e r y apparent  t h a t under  these  e x p e r i m e n t a l c o n d i t i o n s , t h i s r e l a t i o n s h i p does not a p p l y t o those mink  24  which e x c r e t e d  i n excess of 5 mg o f u r i n a r y n i t r o g e n p e r C a l o r i e of  c a l c u l a t e d b a s a l heat produced is  (9).  One reason f o r t h i s h i g h f i g u r e  t h a t n i t r o g e n e x c r e t i o n d u r i n g a p e r i o d o f s t a r v a t i o n i s not the  i r r e d u c i b l e minimum.  I t i s w e l l recognized  t h a t under c o n d i t i o n s o f  f a s t the presence of c a r b o h y d r a t e has a s p a r i n g " a c t i o n on p r o t e i n catabolism  (8).  T h i s i m p l i e s t h a t n i t r o g e n i s not o n l y r e q u i r e d f o r  r e p l a c i n g endogenous p r o t e i n l o s s e s o f the a n i m a l , but i s a l s o i n t i m a t e l y associated with  the m o b i l i z a t i o n o f f a t .  Under c o n d i t i o n s o f s t a r v a t i o n ,  an i n c r e a s e i n water i n t a k e can cause a pronounced i n c r e a s e i n u r e a n i t r o g e n due t o a s t i m u l a t i o n of p r o t e i n c a t a b o l i s m  (13).  Despite  these f a c t o r s , i t does appear t h a t even under c o n d i t i o n s o f s t a r v a t i o n , the u r i n a r y n i t r o g e n e x c r e t i o n o f the mink i s e x t r a o r d i n a r i l y h i g h when compared w i t h  other  s p e c i e s under s i m i l a r c o n d i t i o n s .  Nevertheless,  the data a r e i n good agreement w i t h measurements made by O l d f i e l d ( 1 9 ) , who was working w i t h mink.  M i t c h e l l (17) s t a t e s t h a t the minimal  n i t r o g e n e x c r e t i o n and b a s a l metabolism r e p r e s e n t the organism.  the i d l i n g speed o f  There i s , however, some e v i d e n c e t h a t i n a growing a n i m a l  t h i s r e l a t i o n s h i p a l s o remains f a i r l y  constant.  Blaxter  ( 5 ) , working  w i t h young c a l v e s , found t h a t the more i n t e n s e b a s a l metabolism o f these animals i s a s s o c i a t e d w i t h a more i n t e n s e endogenous n i t r o g e n metabolism, and t h a t the r e l a t i o n s h i p between u r i n a r y n i t r o g e n and b a s a l heat produced was 1.9 Mg/Cal.  T e r r o i n e and Sorg-Matter (23) s t u d i e d  the r a t i o s of endogenous n i t r o g e n t o b a s a l heat p r o d u c t i o n d i f f e r e n t s p e c i e s exposed t o d i f f e r e n t e n v i r o n m e n t a l  i n several  temperatures. /  25  I t was found t h a t a t t h e lower temperatures t h e e l i m i n a t i o n o f endogenous n i t r o g e n i n c r e a s e d as w e l l as d i d t h e b a s a l m e t a b o l i s m and  somewhat i n t h e same p r o p o r t i o n , so t h a t t h e r a t i o o f t h e s e two  e n t i t i e s was n o t g r e a t l y d i s t u r b e d .  I t i may be p o s t u l a t e d , t h e r e f o r e ,  t h a t under n o n - p r o d u c t i v e c o n d i t i o n s , as heat p r o d u c t i o n  increases  so t o o does endogenous n i t r o g e n l o s s , and i n such a manner t h a t t h e r e l a t i o n s h i p between these two e n t i t i e s i s n o t a p p r e c i a b l y Frequent o b s e r v a t i o n s  altered.  of these animals during the f a s t i n g  t r i a l s r e v e a l e d beyond q u e s t i o n t h a t t h e a n i m a l s c o u l d n o t be cons i d e r e d t o be i n the b a s a l s t a t e o f energy m e t a b o l i s m .  U n l i k e many  o t h e r s p e c i e s , a c t i v i t y d i d n o t appear t o d i m i n i s h w i t h f a s t i n g o v e r the p e r i o d o f these t r i a l s .  F u r t h e r m o r e , t h a t t h e normal a c t i v i t y  increment o f t h e mink i s e x c e p t i o n a l l y h i g h has been confirmed feed i n t a k e t r i a l s  through  (11) and t h r o u g h measurements (Table I¥) c a r r i e d  out on f a s t e d mink i n the r e s p i r o m e t e r  (Appendix I ) .  TABLE I V : THE RELATIONSHIP BETWEEN THE HEAT PRODUCTION OF AN UNTRAINED FASTED MINK IN THE RESPIROMETER AND THE ANIMAL'S CALCULATED BASAL METABOLISM RATE  Mink No. P5 P6 P2 P2 P4  B.W. (gms) 688 714 760 755 889  Ambient Temp. °C 17.0 21.0 16.3 16.2 16.1  C a l c u l a t e d B.M.R. (84W * ) C a l . 1  0  57.7 59.7 63.8 63.4 74.8  Period (hours) 2.32 1.22 1.16 1,20 3.46  Measured Heat Production (Cal/24hrs) 186.8 187.1 259.2 228,6 215.0  Ratio of H.P./B.M.R.  3.20 3.13 4,06 3.60 2.87  26  When one c o n s i d e r s the s m a l l dimensions o f the cage i n the respirometer,  and t h a t these animals were n o t n o t i c e a b l y a c t i v e  f o r the e n t i r e p e r i o d o f heat p r o d u c t i o n measurements, the f i g u r e s are e x t r a o r d i n a r i l y high. In o r d e r t o o b t a i n some e s t i m a t e regression equation  o f energy u t i l i z a t i o n , the  (y=0.226X+1A„0) r e l a t i n g apparent  digestible  energy i n t a k e i n C a l o r i e s t o body weight, d e r i v e d from o t h e r work w i t h these mink (11) , was used t o c a l c u l a t e heat p r o d u c t i o n and i s i n good agreement w i t h  the energy o b t a i n e d by r e l a t i n g the C a l o r i c  to weight l o s s as suggested by Wishnofsky (25)„ heat p r o d u c t i o n  this calculated  f i g u r e , the mean r a t i o o f u r i n a r y n i t r o g e n e x c r e t i o n  i n mg t o C a l (A.D.E.) f o r a l l mink becomes 2.5. t h e r e f o r e , t h a t although it  Using  equivalent  I t would appear,  the n i t r o g e n requirement o f a mink i s h i g h ,  i s n o t so when r e l a t e d t o t h i s animal's maintenance heat  production.  I t i s worthy o f note t h a t f a s t i n g s t u d i e s on w i l d and on l a b o r a t o r y rats  (2) r e v e a l e d t h a t the w i l d r a t s had a c o n s i d e r a b l y h i g h e r  production  than t h e i r c o u n t e r p a r t s ,  urinary nitrogen loss.  endogenous  The a d u l t c a t not o n l y has an a p p a r e n t l y  d i e t a r y p r o t e i n requirement but  as w e l l as a h i g h e r  heat  high  (16) i n k e e p i n g w i t h a h i g h energy i n t a k e ,  t h i s s p e c i e s e x c r e t e s about 0.4 gm o f endogenous u r i n a r y  nitrogen/kg  body weight on a n i t r o g e n - f r e e d i e t  to r e q u i r e 0.36 gm n i t r o g e n / k g  (16) and i s r e p o r t e d  body weight f o r n i t r o g e n b a l a n c e ( 1 ) .  S i n c e the C a l o r i c i n t a k e o f an a d u l t c a t has been found t o be about 80-90 C a l o r i e s / k g / d a y  (16), the r a t i o o f endogenous u r i n a r y n i t r o g e n  per C a l o r i e i s t h e r e f o r e about 4.0.  27  Mitchell  (17) and many o t h e r s have suggested t h a t  this  n i t r o g e n : e n e r g y r e l a t i o n s h i p i s a good e s t i m a t e of the minimum p r o t e i n requirements o f a mature a n i m a l .  T h i s statement must be  accepted w i t h a good d e a l of r e s e r v a t i o n when one c o n s i d e r s t h e marked decrease i n the urea f r a c t i o n o f the u r i n e from animals conditions of f a s t diet  (12).  under  ( 6 ) , and from animals r e c e i v i n g a low n i t r o g e n  The urea n i t r o g e n l e v e l can decrease t o as low as 70% o f  the t o t a l n i t r o g e n i n the f a s t i n g man (4) and 81.5% i n the f a s t i n g dog  (13) .  ruminants.  Even lower f i g u r e s have been r e p o r t e d by B l a x t e r  (6) f o r  T h i s d i s t r i b u t i o n of n i t r o g e n would n o t o n l y o v e r e s t i m a t e  the animal's minimal p r o t e i n requirements b u t , under c o n d i t i o n s o f f a s t , c o u l d o v e r e s t i m a t e the p r o t e i n t i s s u e c a t a b o l i z e d i f the t o t a l n i t r o g e n f i g u r e i s used t o determine t h i s  protein.  From these r e s u l t s , one may conclude t h a t a l t h o u g h the a d u l t mink has a h i g h d i e t a r y p r o t e i n requirement when expressed as a percentage o f the r a t i o n , i t i s n o t unduly so i f i t i s expressed on a p e r C a l o r i e b a s i s because demands.  o f t h i s animal's h i g h maintenance  energy  28  BIBLIOGRAPHY  1.  A l l i s o n , J.B., S.A. M i l l e r , J.R. McCoy and M.K. Brush. 1956. S t u d i e s on t h e n u t r i t i o n of t h e c a t . The North Am. V e t . 37, 38.  2.  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P r o t e i n requirements f o r growth of w e a n l i n g k i t t e n s and young c a t s m a i n t a i n e d on a mixed d i e t . Brit. J . Nutrition, 10, 311-316.  8.  E v e r e t t , M.R. 1942. M e d i c a l b i o c h e m i s t r y H a m i l t o n M e d i c a l Books, London.  9.  F a r r e l l , D.J. (Included  1966 a. P a r t I . i n this thesis.)  2nd ed.  The m e t a b o l i c  Carnegie  Hamish  r a t e o f t h e mink.  10.  F a r r e l l , D.J. 1966 b . P a r t I I I . The e f f e c t s of t h e a d d i t i o n of f i b r e t o t h e r a t i o n . (Included i n t h i s t h e s i s . )  11.  F a r r e l l , D.J. 1966 c. P a r t IV. Energy requirements f o r maintenance. (Included i n t h i s t h e s i s . )  12.  F i s h e r R.B.  13.  Howe, P.E., H.A. M a t t i l l and P.B. Hawk. 1912. F a s t i n g s t u d i e s . VI. D i s t r i b u t i o n o f n i t r o g e n d u r i n g a f a s t of one hundred and seventeen days. J . B i o l . Chem. 11, 103-127.  1954. P r o t e i n metabolism.  Meuthen, London.  29  14.  Lusk, G. 1928. The elements of the s c i e n c e of n u t r i t i o n . Saunders, P h i l a d e l p h i a .  15.  McKenzie, R.M. 1964. The response of the l a b o r a t o r y r a t to changes i n the c a l o r i c d e n s i t y and p r o t e i n : c a l o r i e r a t e s of i t s r a t i o n . Unpublished Master's t h e s i s , Dept. o f Animal S c i . , U n i v e r s i t y o f B r i t i s h Columbia.  16.  M i l l e r , S.A. and J.B. A l l i s o n . 1958. The d i e t a r y n i t r o g e n requirements o f the c a t . J . N u t r i t i o n , 64_, 493-501.  17.  M i t c h e l l , H.H. animals.  18.  N e s e n i , R. and B. P i a t k o w s k i . 1959. ( T r a n s i t time of feed i n mink) A r c h . T i e r e r n M h r . .8, 296. (Quoted i n N u t r . A b s t r . and Revs. 1959. 29^, 507)  19.  O l d f i e l d , J.E. 1949. A study o f n i t r o g e n metabolism w i t h s p e c i a l r e f e r e n c e t o mink. Unpublished Master's t h e s i s , Dept. of Animal S c i . , U n i v e r s i t y of B r i t i s h Columbia.  20.  S i b b a l d , I.R., D.G. S i n c l a i r , E.V. Evans and D.L.T. Smith. 1962. The r a t e of passage of feed through the d i g e s t i v e t r a c t of the mink. Can. J . Biochem. and P h y s i o l . 40-, 1391-1394.  21.  Smuts, D.B. 1935. The r e l a t i o n between the b a s a l metabolism and the endogenous n i t r o g e n metabolism, w i t h p a r t i c u l a r r e f e r e n c e t o the e s t i m a t i o n of the maintenance requirement of p r o t e i n . J . N u t r i t i o n , 9^, 403-433.  22.  T e r r o i n e , E.F. and H. Sorg-Matter. 1927. L o i q u a n t i t a t i v e de l a despense azot£e minime des homeothermes:Validite interspecifique. A r c h , intern, p h y s i o l . 29^ 121-132.  23.  T e r r o i n e , E.F. and H. Sorg-Matter. 1928. I n f l u e n c e de l a temperature exte"neure sur l a defense azot£e endogene des homeothermes. A r c h , intern, p h y s i o l . ^0, 115-125.  24.  Waterhouse, H.N. and D.S. Camer. 1962. Growth r a t e , food and c a l o r i e consumption o f l a b o r a t o r y c a t s . P r o c . Animal Care P a n e l , 12, 267-274.  25.  Wishnofsky, M. 1958. C a l o r i c e q u i v a l e n t of gained or weight. Amer. J . Anim. N u t r i t i o n , 6_, 542-546.  26.  Wood, A . J . 1956. The b l a c k fox magazine and modern mink b r e e d e r . 39_, ( 1 ) , 12.  1962. Comparative n u t r i t i o n o f man V o l . 1. Academic P r e s s , New York.  and  domestic  lost  THE NUTRITION OF THE FEMALE PASTEL MINK (Mustela  vison)  PART I I I :  THE EFFECT OF THE ADDITION OF FIBRE TO THE RATION  30  INTRODUCTION  I t i s w e l l known t h a t the time of feed passage of the mink is exceptionally rapid has  (17,  23).  been s t u d i e d by Wood (25).  The  e f f e c t s of d i f f e r e n t markers  Data from t h i s l a b o r a t o r y  (unpublished)  on the time of feed passage of the l a b o r a t o r y r a t would i n d i c a t e t h a t the l e v e l of d i e t a r y . f i b r e w i l l a f f e c t the t r a n s i t d i g e s t i v e system. may  I t has  (13).  may  has  studied  d i e t of the l a b o r a t o r y r a t and  the r a t e  of  the e f f e c t of f i b r e l e v e l i n the  i t s e f f e c t on the d i g e s t i b i l i t y of  of i t s major components.  the d i g e s t i b i l i t y 16,  tend to i n c r e a s e  intestinal  feed.  McKenzie (12)  r a t i o n and  draw m o i s t u r e i n t o the  Both these f a c t o r s w i l l  passage of the  the  been suggested t h a t the f i b r e i n a r a t i o n  i n c r e a s e p e r i s t a l s i s and  tract  time through  of v a r i o u s  feed  Much i n f o r m a t i o n  i n g r e d i e n t s by  the  i s a v a i l a b l e on  the mink (1, 10,  11,  19). The  o b j e c t of t h i s experiment i s to study the e f f e c t of  l e v e l i n a mink r a t i o n on the time of passage of the feed d i g e s t i v e t r a c t and i t s components.  through  fibre the  on the apparent d i g e s t i b i l i t y of the r a t i o n and  Nitrogen  w i t h these d i g e s t i b i l i t y  b a l a n c e s t u d i e s were c a r r i e d out trials,  i n order  to a s c e r t a i n any  of  concurrently change i n  n i t r o g e n r e t e n t i o n w i t h season or w i t h d i f f e r e n t d i e t a r y f i b r e  levels.  EXPERIMENTAL  General N i t r o g e n b a l a n c e s t u d i e s and d i g e s t i b i l i t y s t u d i e s were c a r r i e d out i n metabolism feeders  (22).  cages  ( 4 ) , f i t t e d w i t h m o d i f i e d mink  P r i o r to the s t a r t of a t r i a l ,  f o r f i v e and o n e - h a l f hours. ad l i b i t u m , a b a s a l r a t i o n  the mink were f a s t e d  They were then weighed and f e d ,  ( T a b l e I ) , or the b a s a l r a t i o n p l u s a  measured q u a n t i t y of n o n - n u t r i t i v e b u l k .  Proximate a n a l y s i s  and  c o m p o s i t i o n of these r a t i o n s are shown i n T a b l e I I . The d i g e s t i b i l i t y t h r e e and o n e - h a l f hours.  s t u d i e s c o n t i n u e d f o r a p e r i o d of  fifty-  At the end o f f o r t y e i g h t hours, feed  removed and f i v e and o n e - h a l f hours l a t e r the mink were weighed r e t u r n e d to t h e i r ranch-type  was and  pens.  During the " t e s t p e r i o d " , ( i ) the animals were f e d t h r e e times a day, (iii)  ( i i ) a l l waste feed was  gathered and weighed d a i l y ,  the t o t a l f a e c e s e x c r e t e d were c o l l e c t e d  daily.  Animals Four a d u l t female p a s t e l mink were used to determine  the  apparent d i g e s t i b i l i t y of the r a t i o n and of i t s major components. The time of passage  s t u d i e s were determined  the n i t r o g e n r e t e n t i o n  studies.  on s i x animals as were  and  TABLE I :  THE COMPOSITION OF THE BASAL RATION ON AN "AS MIXED" BASIS  Ingredient Cereal  Mix  Per 1  Cent of the R a t i o n 30.5  Horse Meat  19.3  Pork L i v e r  2.9  Fish  26.1  2  Corn O i l Water  8.7 12.5  The r a t i o n was mixed i n a s i n g l e b a t c h and then f r o z e n i n 800 gm l o t s i n p l a s t i c bags, and was s t o r e d a t -20°C.  1.  See Appendix I I  2.  E q u a l q u a n t i t i e s of grey cod (Gadus macrocephlus) and dover s o l e (Microstomus p a c i f i c u s )  33  TABLE I I :  COMPOSITION AND MEAN RESULTS OF ANALYSES OF THE DIETS USED  Ration %  Basal  Basal  100  100  -  -  65  65  Alphacel  3  MC%  1  Basal  2  B a s a l +7  B a s a l +14  B a s a l +20  93  86  80  7  14  20  65  65  65  6  6  4  29.0  27.4  26.3  22.6  8.8  6.5  A n a l y s i s % on dry weight b a s i s No. o f Samples  6  Lipids  30.8  Ash  7.. 1  Protein  30.8  8  32.4  6.1  29.1  5.7 24.8  25.3  Gross energy Cal/gm  5.81  5.81  5.58  5.51  5.28  A.D.E. Cal/gm  4.47  4.47  3.97  3.72  3.37  A.D.N.,mg A.D.E.,Cal  1.  78.4  78.4  74.0  82.9  B l i g h and Dyer - c h l o r o f o r m e x t r a c t e d  78.0 .  samples - A n a l y s i s on whole samples.  2.  Petroleum e t h e r e x t r a c t e d  samples.  A n a l y s i s on e x t r a c t e d  3.  N u t r i t i o n a l B i o c h e m i c a l Corp., C l e v e l a n d ,  Ohio.  samples.  A n a l y t i c a l Methods (a) Dry matter was  determined by d r y i n g  samples a t 100°C to a constant  weight.  (b) Crude p r o t e i n (Nx6.25) and determined by a m i c r o - k j e l d a h l (c) N o n - v o l a t i l e ash was  representative  urinary nitrogen  was  procedure. determined by h e a t i n g  samples  at 600°C f o r twelve h o u r s . (d) T o t a l l i p i d s were e x t r a c t e d u s i n g modified  method ( 3 ) .  petroleum e t h e r  The  b a s a l r a t i o n was  (30-60°C b o i l i n g r a n g e ) .  the B l i g h and also extracted  A n a l y s i s f o r ash  n i t r o g e n were then c a r r i e d out on the e x t r a c t e d r e s i d u e . comparative purposes, these two shown i n Table  Dyer with and For  s e t s of proximate a n a l y s i s are  II.  (e) Gross energy v a l u e s were o b t a i n e d  by combustion i n a  P a r r a d i a b a t i c oxygen bomb. ( f ) Dry matter d i g e s t i b i l i t y was c o l l e c t i o n of the feed and  Time of Passage  measured through  total  faeces.  Studies  Time of passage s t u d i e s on mink housed i n r a n c h - s t y l e cages commenced a t 8:30  a.m.  At t h i s time, feed c o n t a i n e r s were washed  r e p l e n i s h e d w i t h a f e r r i c oxide-marked f e e d .  The mink c o u l d  be  observed through a window i n an a d j o i n i n g room w i t h a minimum of disturbance  to the  animals.  and  35  RESULTS AND DISCUSSION  1. Time o f Passage The e f f e c t o f r a t i o n f i b r e l e v e l on the times of passage has been summarized i n T a b l e I I I .  TABLE I I I :  Ration  Basal  Mean time of passage (mins.)  TIME (MINUTES) REQUIRED FOR A MARKED FEED TO APPEAR IN THE FAECES OF FEMALE PASTEL MINK ON DIETS CONTAINING VARIOUS FIBRE LEVELS  B a s a l +7  137  Standard deviation  31.6  No. o f Determinations  10  B a s a l +14  B a s a l +20  109  102  119  21.8  28.5  29.7  10  There appears t o be an i n v e r s e r e l a t i o n s h i p between t h e time of passage of the feed through the d i g e s t i v e t r a c t and the f i b r e l e v e l i n the r a t i o n .  The i n d i v i d u a l times o f passage ranged from 73 minutes  on the h i g h e s t f i b r e r a t i o n t o 200 minutes on the b a s a l f e e d .  2. Apparent D i g e s t i b i l i t y The apparent d i g e s t i b i l i t y o f the r a t i o n and o f i t s major components a r e p r e s e n t e d i n F i g u r e 1.  A l l d e t e r m i n a t i o n s were c a r r i e d  FIGURE  1:  THE APPARENT DIGESTIBILITY OF THE FAT, PROTEIN, ASH AND COMPLETE RATIONS, AS AFFECTED BY FIBRE LEVEL IN THE RATION  ADDED FIBRE TO THE RATION, %  37  out on the same t h r e e mink, except f o r those on the h i g h e s t f i b r e r a t i o n , when two mink were used. The r e s u l t s c l e a r l y show t h a t the apparent  digestibility  of the ash component of the r a t i o n i s g r e a t l y decreased by  increased  f i b r e l e v e l i n the r a t i o n and decreases more or l e s s i n a l i n e a r fashion.  The apparent d i g e s t i b i l i t y of the f a t i s o n l y s l i g h t l y  reduced a t the 20% f i b r e l e v e l w h i l e the p r o t e i n f r a c t i o n s t a r t s to decrease a t l e v e l s of d i e t a r y f i b r e i n excess o f  7%.  S i n c e an i n v e r s e r e l a t i o n s h i p e x i s t s between the r a t e o f passage of the feed through the d i g e s t i v e t r a c t and the r a t i o n  fibre  l e v e l , t h e r e would be a decrease i n the time d u r i n g which the d i g e s t i v e enzymes are i n c o n t a c t w i t h t h e i r s u b s t r a t e s .  The  inclusion  of a n o n - n u t r i t i v e b u l k i n the r a t i o n would presumably s h i e l d r a t i o n components from the enzymes.  the  McKenzie (12) has shown t h a t w i t h  the l a b o r a t o r y r a t , a decrease i n the apparent d i g e s t i b i l i t y of both p r o t e i n and f a t d i d not o c c u r a t r a t i o n f i b r e l e v e l s below McKenzie (12) suggests t h a t t h i s decrease i n apparent may  24%.  digestibility  be due i n p a r t t o an i n c r e a s e i n endogenous f a e c a l f a t and  p r o t e i n as measured by Meyer (14).  faecal  The a b i l i t y of the mink to  e f f i c i e n t l y d i g e s t f a t suggests t h a t t h i s animal i s p r o v i d e d w i t h an abundance of l i p a s e .  I t has been r e c o g n i z e d f o r some time t h a t the  a d u l t mink can e f f e c t i v e l y handle h i g h l e v e l s of d i e t a r y f a t ( 2 4 ) . The a d u l t c a t can e q u a l l y w e l l acept h i g h f a t d i e t s  (19).  S i n c e the  38  f a t content it  of mink m i l k on a d r y weight b a s i s i s about 35% ( 7 ) ,  i s reasonable  t o expect t h a t the mink k i t can a l s o r e a d i l y d i g e s t  fat. Of some p r a c t i c a l s i g n i f i c a n c e i s the marked d e p r e s s i o n o f the apparent d i g e s t i b i l i t y o f the ash component even a t low f i b r e levels.  T h i s low d i g e s t i b i l i t y o f ash c o u l d c o n c e i v a b l y  mineral  d e f i c i e n c y during periods  mineral  requirements o f t h i s s p e c i e s must t h e r e f o r e r e c o g n i z e the  l e v e l of d i e t a r y f i b r e i n order  of s t r e s s .  lead to a  A c o n s i d e r a t i o n of the  t o ensure an adequate a b s o r p t i o n of  these elements.  3. N i t r o g e n  Retained  The measurements r e l a t i n g t o the n i t r o g e n b a l a n c e s t u d i e s c a r r i e d out on each mink a r e p r e s e n t e d  i n T a b l e IV.  The n i t r o g e n r e t a i n e d has been expressed i n mg. N / 1 0 0 gm o f body weight and as a percentage o f the absorbed feed n i t r o g e n .  This  l a t t e r f i g u r e , o f t e n used as a measure o f n i t r o g e n r e t e n t i o n , has l i t t l e v a l u e when each mink r e c e i v e s d i f f e r e n t q u a n t i t i e s of p r o t e i n . The r e t a i n e d n i t r o g e n may remain r e l a t i v e l y constant to i n c r e a s e w i t h  decreasing  but i t w i l l  appear  n i t r o g e n i n t a k e when expressed as a  percentage o f the absorbed n i t r o g e n . The n i t r o g e n r e t a i n e d appears t o be g r e a t e s t i n September and  tends t o decrease t h e r e a f t e r .  increment a s s o c i a t e d w i t h  T h i s t r e n d may r e f l e c t  f u r growth.  the p r o t e i n  I t i s , however, d i f f i c u l t t o  TABLE IV:  Mean Body Weight gm  THE APPARENT NITROGEN RETAINED BY FEMALE PASTEL MINK DURING METABOLISM STUDIES  Weight Change gm  Absorbed Feed Nitrogen gm  Urinary Nitrogen gm  Nitrogen Retained for period gm  Nitrogen Retained  Nitrogen Retained /day  Nitrogen Retained Mg/day /100 gm B.W.  Mink No  Month  Ration  P4 P5 P6  Sept Sept Sept  Basal Basal Basal  804 722 650  -5 +23 +2  2.632 2.323 3.865  2.060 2.180 2.642  0.572 0.143 .1.223  21.7 6.2 31,6  257 64 548  32.0 8.8 84.3  PI P2 P5  Jan Jan Jan  Basal Basal Basal  821 724 730  -9 -28 -16  .2.674 2.643 2.332  2.640 2.394 2.116  0.034 0.249 0.216  1.3 9.4 9.3  15 117 97  1.8 16.3 29.5  PI P2 P5  Jan Jan Jan  B a s a l +7 B a s a l +7 B a s a l +7  717 703 701  -2 -6 +4  3.427 3.422 3.538  3.105 3.052 3.262  0.322 0.370 0.276  9.4 10.8 7.8  144 166 124  20.1 23.6 17.7  PI P2 P5  Dec Dec Dec  B a s a l +14 B a s a l +14 B a s a l +14  852 722 690  +15 -13 +1  2.988 2.746 3.004  2.786 2.529 2.918  0.202 0.217 0.086  6.8 7.9 2.9  91 97 38  P4 P5  Nov Nov  B a s a l +20 B a s a l +20  666 660  +9 +9  2.715 2.783  2.336 2.460  0.379 0.323  14.0 11.6  170 145  %  rricr  10.6 13.5 5,6: 25.5 21.8  40  account f o r the h i g h n i t r o g e n r e t e n t i o n f i g u r e s o b t a i n e d  f o r mink  d u r i n g January, e s p e c i a l l y when the animals were l o s i n g weight. c o r r e c t i o n f o r endogenous n i t r o g e n retained figure. c a r r i e d out by  l o s s e s would merely i n c r e a s e  These d a t a are i n c l o s e agreement w i t h  S i n c l a i r & Evans (21).  gave v a l u e s 5.6,  22.4,  of n i t r o g e n r e t a i n e d 29.6  being u t i l i z e d  and  14.8.  The  (mg  low  per  100  gm  eight.mink,  of body weight) of  and  the animals:'' p r o t e i n  requirements second, when other n u t r i e n t s i n the r a t i o n are to meet the a n i m a l s ' energy r e q u i r e m e n t s . ( 2 ) .  insufficient  Roberts and K i r k  working w i t h a d u l t female mink, have r e p o r t e d o f f e r no  data  f i g u r e i s a good example of p r o t e i n  to meet energy purposes f i r s t ,  of n i t r o g e n r e t a i n e d , but  the  studies  R e c a l c u l a t i o n of t h e i r  from f o u r of t h e i r groups of animals, each c o n t a i n i n g  Any  even g r e a t e r  explanation  (13),  quantities  f o r the magnitude of  these f i g u r e s . The  c o n t i n u a l replacement of dermal and  account f o r p a r t of the n i t r o g e n r e t a i n e d . these l o s s e s and  and  Elvehjerh  Oldfield  found them to be n e g l i g i b l e .  of f u r growth i s not (9).  M i t c h e l l (15)  has  f o r h a i r growth would be 100  gm  may  measured  A continual high  rate  Leoschke  c a l c u l a t e d t h a t the d a i l y growth N/day on the  t h a t the r a t c y c l e s i t s h a i r every 35 days.  f o r the mink per  (18)  l i k e l y on the b a s i s of the work done by  of h a i r i n the r a t w i l l account f o r 42 mg  nitrogen  hair losses  assumption  T h i s increment of  i n the same range as t h a t measured  of body weight.  A f i n a l p o s s i b i l i t y i s a l o s s of n i t r o g e n i n the form o f ammonia, through pathways o t h e r  than those measured i n t h i s  study.  Because ammonia has a h i g h d i f f u s i o n r a t e through t i s s u e s ( 6 ) , and because h i g h l e v e l s o f meat p r o t e i n can e l e v a t e b l o o d ammonia ( 7 ) , l o s s e s of; n i t r o g e n through the lungs substantialo  levels  and i n the f a e c e s may be  The ammonia i n the l a t t e r component c o u l d o n l y be  measured i f the f a e c e s were c o l l e c t e d i n a c i d o r almost  immediately  following defecation. The  c o n s i s t e n t l y small p o s i t i v e n i t r o g e n balance  t h a t the mink has a c o n s t a n t  suggests  demand f o r p r o t e i n which i s u t i l i z e d  f o r p r o d u c t i v e purposes, the most obvious o f which i s f u r growth, and  i s l o s i n g n i t r o g e n as ammonia through v a r i o u s  channels.  42  BIBLIOGRAPHY  lo  B e r n a r d , R., S.E. Smith and L.A. Maynard. 1942. D i g e s t i o n o f c e r e a l s by minks and foxes w i t h s p e c i a l r e f e r e n c e t o s t a r c h and crude f i b r e . C o r n e l l V e t . 32_, 29-36.  2.  B l a x t e r , K.L. and W.A. Wood. 1952. N u t r i t i o n of t h e young Ayrshire c a l f . 4. Some f a c t o r s a f f e c t i n g the b i o l o g i c a l v a l u e o f p r o t e i n determined by n i t r o g e n - b a l a n c e methods. B r i t . J . N u t r i t i o n , _5, 55-67.  3.  B l i g h , E.G. and W.J. Dyer. 1959. A r a p i d method o f t o t a l l i p i d e x t r a c t i o n and p u r i f i c a t i o n . Can. J . Biochem and P h y s i o l . 37, 911.  4.  F a r r e l l , D.J. 1966. P a r t I I . S t u d i e s on the f a s t i n g mink. (Included i n t h i s thesis)  5.  F a r r e l l , D.J.  1966. P a r t  maintenance.  IV. Energy requirements f o r  (Included i n t h i s  1966. P e r s o n a l  thesis)  6.  Groves, T.D.D.  communication.  7.  Harper, H.A. 1963. Review of p h y s i o l o g i c a l c h e m i s t r y . 9th ed. Lange M e d i c a l P u b l i c a t i o n s , Los A l t o s .  8.  Jorgensen, G. 1960. (Composition and n u t r i t i v e v a l u e of mink m i l k . ) Dansk Pelsdr-avi:, 23, 119-137. (Quoted i n N u t r . A b s t r . & Revs. 1960, 30, 1219.)  9.  Leoschke, W.L. and C.A. Elvehjem.. 1959. The importance o f a r g i n n i n e and methionine f o r growth and f u r development of mink f e d p u r i f i e d d i e t s . J . N u t r i t i o n , 69_, 147-150.  10.  Leoschke, W.L. 1959. The d i g e s t i b i l i t y o f animal f a t s and p r o t e i n s by mink. Am. J . V e t . Res. 20, 1086-1089.  11.  L o o s l i , J.K. and L.A. Maynard. Animal P r o d . , Dec. 400.  12.  McKenzie, R.M. 1964. The response o f t h e l a b o r a t o r y r a t t o changes i n the c a l o r i c d e n s i t y and p r o t e i n : c a l o r i e r a t i o of i t s r a t i o n . Unpublished Master's t h e s i s , Dept. of Animal S c i . , U n i v e r s i t y o f B r i t i s h Columbia.  1939. P r o c . Am. Soc. of  43  13.  Maynard, A.B. and J.K. L o o s l i . 1962. Animal N u t r i t i o n 5th ed. McGraw-Hill Book Company, I n c . , T o r o n t o .  14.  Meyer, J.H. 1956. I n f l u e n c e of d i e t a r y f i b r e on m e t a b o l i c and endogenous n i t r o g e n e x c r e t i o n . J . N u t r i t i o n , 58, 407-414.  15.  M i t c h e l l , H.H. animals.  16.  N o r d f e l t , S., G. M e l i n and B. T h e l a n d e r . 1955. (Digestion experiments w i t h mink.) K g l . L a n t l o u k s hogsk. S t a t e n s H u s d j u r s f o r s o k Sagtyck No. 114, 14. (Quoted i n N u t r . A b s t r . and Revs. 1956, 26^ 830.)  17.  N e s e n i , R. and B. P i a t k o w s k i . 1958. ( T r a n s i t time o f feed i n the mink.) A r c h . Turernahning J3, 296-308. Quoted i n N u t r . A b s t r . and Revs. 1959, 29, 507.  18.  O l d f i e l d , J . E . 1949. A study of n i t r o g e n metabolism w i t h s p e c i a l r e f e r e n c e t o mink. Unpublished Master's t h e s i s , Dept. of Animal S c i . , U n i v e r s i t y o f B r i t i s h Columbia.  19.  R o b e r t s , W.K. and R.J. K i r k . 1965. D i g e s t i b i l i t y and n i t r o g e n u t i l i z a t i o n o f raw f i s h and dry meals by mink. Fur o f Canada. 30, ( 3 ) , 3.  20.  S c o t t , P.P.  21.  S i n c l a i r , D.G., E.V. Evans and I.R. S i b b a l d . 1962 a. The i n f l u e n c e o f apparent d i g e s t i b l e energy and apparent d i g e s t i b l e n i t r o g e n i n the d i e t on weight g a i n , feed consumption and n i t r o g e n r e t e n t i o n of growing mink. Can. J . Biochem. and P h y s i o l . 40, 1375-1589.  22.  S i n c l a i r , D.G. and E.V. Evans. 1962 b. A metabolism cage designed f o r use w i t h mink. Can. J . Biochem. and P h y s i o l . 40, 1395-1399.  23.  S i b b a l d , I.R., D.G. S i n c l a i r , E.V. Evans and D.L.T. Smith. 1962. The r a t e of passage of feed through the d i g e s t i v e t r a c t of the mink. Can. J . Biochem. and P h y s i o l . 40, 1391-1394.  24.  T r a v i s , H.F. and P.J. S c h a i b l e . 1961. E f f e c t of d i e t a r y f a t l e v e l s upon r e p r o d u c t i v e performance o f mink. Quart. B u l l . Michigan A g r i c . Expt. Stat. 43, 518.  25.  Wood, A . J . 1956. The b l a c k f o x magazine and modern mink breeder. 39, ( 1 ) , 12.  1962. Comparative n u t r i t i o n o f man V o l . 1. Academic P r e s s , New York.  1960.  I I . The C a t .  V e t . Record. 72^,  and domestic  6-9.  THE  NUTRITION OF THE FEMALE PASTEL MINK (Mustela  PART IV:  ENERGY REQUIREMENTS FOR MAINTENANCE  vison)  44  INTRODUCTION  The a c c u r a t e measurement of the energy i n t a k e o f an animal under d e f i n e d c o n d i t i o n s i s of prime importance s i n c e i t i s t h i s component of the r a t i o n which p r i m a r i l y governs feed i n t a k e . f a c t has been proven e x p e r i m e n t a l l y w i t h r a t s (9,  2 9 ) , swine  This  (18, 3 1 ) , c h i c k e n s  ( 2 4 ) , dogs ( 2 6 ) , lambs ( 4 ) , c a l v e s  ( 1 5 ) , c a t t l e (3)  and mink k i t s ( 3 3 ) . Some d a t a a r e a v a i l a b l e on the energy requirements f o r maintenance  o f a d u l t mink (10, 25, 2 7 ) . These workers do not  g e n e r a l l y s p e c i f y the sex, s t r a i n , season or c o n d i t i o n s under which the  measurements were made.  Because of the f e e d i n g h a b i t s o f the  mink, i t i s extremely d i f f i c u l t t h i s animal^s d a i l y feed i n t a k e .  to measure w i t h any degree of p r e c i s i o n The d i f f i c u l t y  of m a i n t a i n i n g weight  s t a s i s d u r i n g the f e e d i n g t r i a l can o f t e n l e a d t o erroneous conc l u s i o n s s i n c e the energy increment a s s o c i a t e d w i t h weight change i s both v a r i a b l e and d i f f i c u l t  to measure.  F u r t h e r , the energy a s s o c i a t e d  w i t h weight g a i n i s i n excess o f t h a t r e l e a s e d t o the system through weight l o s s o f body t i s s u e .  K i e l o w i o w s k i (12) has e s t i m a t e d the  m e t a b o l i z a b l e energy of 1 gm of p r o t e i n g a i n t o be 7-8 C a l o r i e s , and for  f a t t h i s f i g u r e i s 15 C a l o r i e s f o r the lamb and 11.7 f o r t h e baby  pig.  S i n c e the o x i d a t i o n o f f a t and p r o t e i n y i e l d o n l y 9.3 and 5.6  C a l o r i e s / g m r e s p e c t i v e l y , i t i s c l e a r one cannot v a l i d l y the  associate  same energy v a l u e t o one gram of weight change, even though the  45  composition  of the g a i n and  working w i t h humans, has  l o s s may  estimated  Wishnofsky  (35),  the c a l o r i c e q u i v a l e n t of 1  of body weight g a i n or l o s s to be 4.5 ditions, this figure f a l l s  be i d e n t i c a l .  to 3.2  Calories.  Under f a s t i n g  gm con-  Cal/gm of body weight l o s t .  The  mink, w i t h such a r a p i d time of passage (32, 37), under c o n d i t i o n s of i n f r e q u e n t f e e d i n g , c o u l d be almost c o n s t a n t l y degrading  and  s y n t h e s i z i n g body t i s s u e depending on the presence or absence of In o r d e r to o b t a i n a t r u e p i c t u r e of t h i s animal's energy the presence of feed a t a l l times i s The  i n the course twenty-eight rations  of a study  requirements,  necessary.  enormous weight f l u c t u a t i o n t h a t can occur  mink and between sexes was  among a d u l t  apparent from work done by M c M i l l a n  on f u n g a l t o x i c o s i s .  During  male mink f o r t h a t p e r i o d was on the other hand, gained  The  mean body weight g a i n r e c o r d e d  398  gm.  90 gm.  One  During  gained  740  (17)  a p e r i o d of  days i n January, 12 a d u l t mink were p l a c e d on h i g h  (6000 gross C a l / k g ) .  feed.  gm.  experimentation,  The  energy for females,  o f t e n no  d i s t i n c t i o n between sexes i s made. The  o b j e c t of t h i s experiment i s the a c c u r a t e measurement of  the feed i n t a k e of one  s t r a i n of mink under d e f i n e d c o n d i t i o n s ,  and  of the e f f e c t of f e e d i n g r a t i o n s w i t h v a r y i n g l e v e l s of a v a i l a b l e energy.  46  EXPERIMENTAL  Animals  and  Treatment  F i v e mink were s e l e c t e d  from a group  of seven a d u l t  p a s t e l s of s i m i l a r age, s t r a i n and n u t r i t i o n a l h i s t o r y . i n f e r t i l e males,  female  Because of  these mink d i d not produce k i t s the season p r e c e d i n g  the e x p e r i m e n t a l p e r i o d . With received  the e x c e p t i o n of t h r e e two-weekly p e r i o d s when the mink  'bulked' r a t i o n s , o r when undergoing metabolism  t r i a l s , the  animals were m a i n t a i n e d on the b a s a l r a t i o n .  Rations D e t a i l s of the c o m p o s i t i o n and of the a n a l y s i s of the e x p e r i m e n t a l r a t i o n s a r e o u t l i n e d i n P a r t I I I of t h i s t h e s i s  {8).  Housing The mink were housed i n r e c t a n g u l a r w i r e mesh ranch-type cages, 40 cm h i g h , 45 cm wide and 60 cm l o n g , arranged i n banks of t h r e e and d i v i d e d by means of a double w i r e mesh p a r t i t i o n . cages were suspended  from the w a l l of a room which was  l i g h t e d and v e n t i l a t e d but exposed mental  These  adequately  t o the p r e v a i l i n g o u t s i d e e n v i r o n -  temperatures.  S p e c i a l Equipment The animals were f e d i n mink f e e d e r s ( 3 4 ) . m o d i f i e d i n o r d e r to permit b o l t i n g d i r e c t l y  These were  to the cage.  slightly  A small  47  t r a y was  suspended below the w i r e mesh c y l i n d e r to c o l l e c t  feed  spillage.  Data  Collection  (a) F e e d i n g : The mink were f e d t h r i c e d a i l y a measured q u a n t i t y of feed of known m o i s t u r e c o n t e n t .  Any weigh-back  from the p r e v i o u s  feed was r e c o r d e d . (b) D a i l y R o u t i n e : At 0800 hours - P r i o r to f e e d i n g the a n i m a l s , the feed cups were washed and  dried.  - A l l waste feed was  c o l l e c t e d from the f e e d e r s and from  the aluminum t r a y s . - Faeces and u r i n e were removed from the aluminum t r a y s , which were r e p l a c e d w i t h c l e a n ones. - Water b o t t l e s were checked and r e p l e n i s h e d i f n e c e s s a r y . (c) Feed  weigh-back:  Waste feed c o l l e c t e d  from the t r a y s was  weight.  added any feed a d h e r i n g to the f e e d e r s  To t h i s was  or cage f l o o r which was and was  c o l l e c t e d on wax  d r i e d to a constant  removed by means of a s t e e l w i r e b r u s h , paper.  (d) Weighing: For the purposes of t h i s study, one week c o n s t i t u t e s the i n t e r v a l from 0800 hours Tuesday  to 0800 hours the f o l l o w i n g Tuesday.  On  48  t h i s day the f e e d was then weighed  removed a t 0800 h o u r s , the mink were  a t 1030 hours on a beam b a l a n c e to an attempted  a c c u r a c y of ± 1  gm.  C o n t r o l a n i m a l s , m a i n t a i n e d on a nearby mink r a n c h , were weighed  a p p r o x i m a t e l y each month (Appendix I I I ) .  RESULTS  Because  of the lower s t a n d a r d e r r o r , i t was  found t h a t the  d a t a i s b e s t r e p r e s e n t e d by an a r i t h m e t i c r a t h e r than a l o g a r i t h m i c regression equation. energy  The r e l a t i o n s h i p between apparent  digestible  (A.D.E.) i n t a k e and the mean body weight of a l l mink housed i n  ranch-type cages d u r i n g L t h e p e r i o d September 1 and January 21, has been summarized  i n F i g u r e 1.  Symbols have been s e l e c t e d i n o r d e r t o  d i s t i n g u i s h between those animals which showed no weight change (± 10 gm)  from those which gained or l o s t weight  seven day  period. The mean A.D.E. i n t a k e  weight s t a s i s  (± 10 gms)  (>± 10 gm)  ( C a l s ) of those mink t h a t  during a  demonstrated  on the b a s a l r a t i o n f o r a p e r i o d o f seven  days between September 1 and November 29 has been p l o t t e d body weight and i s p r e s e n t e d i n F i g u r e 2.  Because  against  of the h i g h l y  significant correlation  (r=0.805) of the d a t a and because the mink  showed no weight change,  t h i s e q u a t i o n w i l l r e p r e s e n t the s t a n d a r d  curve f o r these] mink m a i n t a i n e d under r e c o g n i z e d t h a t the maintenance  the s t a t e d c o n d i t i o n s .  energy i n c l u d e s an increment  It i s  FIGURE 1: THE RELATIONSHIP BETWEEN THE APPARENT DIGESTIBLE AND  ENERGY INTAKE  THE BODY WEIGHT OF ALL MINK ON ALL FOUR RATIONS AND  HOUSED IN RANCH-TYPE CAGES.  (Symbols have been used i n order t o d i f f e r e n t i a t e between those animals which l o s t weight from those which gained or m a i n t a i n e d body weight.)  FIGURE 2: THE RELATIONSHIP BETWEEN THE APPARENT D I G E S T I B L E ENERGY INTAKE AND THE BODY WEIGHT OF THOSE MINK WHICH SHOWED NO WEIGHT CHANGE AND WERE HOUSED I N RANCH-TYPE CAGES AND MAINTAINED ON THE BASAL RATION  IOOU  TOO  !  i BODY WEIGHT, grams  8  0  0  5  0  0  FIGURE 3: THE RELATIONSHIP BETWEEN THE APPARENT DIGESTIBLE ENERGY INTAKE AND THE BODY WEIGHT OF MINK RECEIVING THE BASAL RATION AND HOUSED IN METABOLISM  CAGES  (Data from o t h e r sources have been i n c l u d e d f o r comparative purposes.)  BODY WEIGHT, grams  52  a s s o c i a t e d w i t h f u r growth and temperature f l u c t u a t i o n s . d i d the temperature f a l l below 7°C. the e n t i r e p e r i o d was  At no time  The mean d a i l y temperature f o r  10.7°C.  In view of the above r e s u l t s , the q u e s t i o n a r i s e s as to whether  r e s t r i c t i o n of the cage c a p a c i t y w i l l i n f l u e n c e feed  intake.  For t h i s r e a s o n , the A.D.E. ( C a l ) i n t a k e by animals m a i n t a i n e d f o r s h o r t p e r i o d s of time i n the s m a l l e r metabolism cages on the b a s a l r a t i o n has been p l o t t e d a g a i n s t mean body weight of s i g n i f i c a n c e  (Figure 3).  A test  ('t'=6.672 f o r 24df) shows t h a t these animals consumed  s i g n i f i c a n t l y l e s s feed than when housed i n r a n c h - t y p e cages.  For  comparative purposes, p l o t t e d on t h i s same graph i s the d a t a o f Hodson and Smith (10) on which the 1953 N.R.C. (23) maintenance requirements f o r energy f o r thei mink a r e based.  Measurements o b t a i n e d by  S i n c l a i r , e t a l (33) have been p l o t t e d on the same graph.  These d a t a  have been s e l e c t e d because they were o b t a i n e d from mink housed i n s m a l l metabolism cages. In o r d e r to t e s t the h y p o t h e s i s t h a t a mink e a t s to meet an energy requirement, a comparison of the mean c a l o r i c i n t a k e of those mink which were m a i n t a i n e d on the b a s a l r a t i o n w i t h o u t weight change w i t h the energy i n t a k e of those mink r e c e i v i n g the b a s a l r a t i o n p l u s added  f i b r e , showed no s i g n i f i c a n t d i f f e r e n c e  between energy i n t a k e and body weight.  ('t'=0.851 f o r 41df)  However, when a comparison  was made between the same group on the b a s a l r a t i o n and those mink on the r a t i o n s w i t h added  f i b r e a l s o showing no weight change,  there  was  a significantly  the l a t t e r group. Figure  4.  ('t'=3.892 f o r 26df) lower energy i n t a k e by The d a t a has been i l l u s t r a t e d g r a p h i c a l l y i n  FIGURE 4:  A DIAGRAMMATIC REPRESENTATION OF THE APPARENT DIGESTIBLE ENERGY INTAKE OF EACH INDIVIDUAL MINK ON THE FOUR RATIONS AND OF THEIR WEIGHT CHANGES WHILE ON THE RATIONS  Each b a r r e p r e s e n t s the mean d a i l y A.D.E. i n t a k e expressed i n Cal/100 gm body weight f o r a one week period. The h e a v i l y shaded areas r e p r e s e n t weight g a i n , i f p l a c e d a t the top of a b a r , and weight l o s s i f p l a c e d a t the bottom of a b a r . One c e n t i m e t r e i s e q u a l t o t h i r t y grams o f weight change. The b a r r e p r e s e n t i n g the b a s a l r a t i o n (unshaded) i s the mean f i g u r e o f a l l measurements d u r i n g which the animal demonstrated weight s t a s i s .  DISCUSSION  The main purpose of t h i s study has been to e s t a b l i s h a r e l a t i o n s h i p between body weight and the energy u t i l i z e d by s t r a i n of mink f o r maintenance purposes.  this  In t h i s experiment, i t has  been c o n s i s t e n t l y found t h a t energy e x p e n d i t u r e f o r maintenance purposes tends to v a r y d i r e c t l y w i t h body weight and not w i t h body weight r a i s e d to some f r a c t i o n a l power, as has been found by workers  (1, 5,13)  several  f o r i n t e r s p e c i f i c comparisons of b a s a l metabolism.  Without much e x p e r i m e n t a l e v i d e n c e , these f i n d i n g s a r e o f t e n extended i n order to e s t i m a t e i n t r a s p e c i f i c energy requirements f o r maintenance (22).  Because  the p r e s e n t measurements r e l a t i n g energy i n t a k e t o  body weight cover animals d i s p l a y i n g o n l y a narrow weight range, a curve j o i n i n g the two weight e x t r e m i t i e s would appear to be almost l i n e a r i f i t were p l a c e d on the e n t i r e i n t e r s p e c i f i c s c a l e as c a l c u l a t e d from Brody's e q u a t i o n ( 5 ) .  The p r e s e n t d a t a , even i f i t  were expressed as body weight to a power f u n c t i o n of 0.73, f a l l w i t h i n the s t a n d a r d e r r o r l i m i t s of Brody's d a t a .  would  still  Some i n t r a -  s p e c i f i c d a t a on b a s a l or r e s t i n g metabolism of h o r s e s (5) and rabbits  (14) show t h a t heat p r o d u c t i o n does not i n f a c t v a r y w i t h body  weight r a i s e d to some f r a c t i o n a l power but w i t h body weight r a i s e d to unity.  T h i s phenomenon i s l e s s s u r p r i s i n g w i t h the mink s i n c e the  increment of energy a s s o c i a t e d w i t h a c t i v i t y i s i n excess o f 200% above the b a s a l energy e x p e n d i t u r e .  There i s some e v i d e n c e t h a t the  energy e x p e n d i t u r e a s s o c i a t e d w i t h muscular a c t i v i t y may  vary d i r e c t l y  56  w i t h body weight maintenance  (21, 5 ) .  On would, t h e r e f o r e , expect the t o t a l  energy requirement of the mink to v a r y w i t h body weight  r a i s e d to a f r a c t i o n a l power c l o s e r to one than t o 0.7, a c t i v i t y i s such an u n u s u a l l y l a r g e p o r t i o n o f the t o t a l energy of t h i s  because maintenance  species.  Of p a r t i c u l a r i n t e r e s t are the measurements a s s o c i a t e d w i t h mink housed  i n metabolism  cages.  The h i g h l y s i g n i f i c a n t  decrease  a s s o c i a t e d w i t h confinement i s expected and i s a l s o of a p p r o x i m a t e l y the  same magnitude as t h a t found i n the c a t ( 2 0 ) .  and Smith  (10) on mink, u n s p e c i f i e d as to sex, s t r a i n or time of y e a r ,  were s e l e c t e d from d i f f e r e n t f e e d i n g t r i a l s , out  The data of Hodson  i n metabolism  they demonstrated  cages.  a l l of which were c a r r i e d  The animals were c a r e f u l l y s e l e c t e d  a fairly  c o n s t a n t body weight  because  throughout the  However, two of the s i x s e l e c t e d mink gained i n excess of 50  trial.  gm.  D e s p i t e the s c a t t e r and apparent l a c k of c o r r e l a t i o n of the d a t e , the requirement of a 1 kg mink i s i n p r e c i s e agreement w i t h t h a t  predicted  by the p r e s e n t e q u a t i o n c a l c u l a t e d from the d a t a on measurements made on mink i n metabolism cages For the  (Figure 3).  p r e s e n t purposes, t h e r e i s l i t t l e  advantage  to c o r r e c t i n g  apparent d i g e s t i b l e energy f o r endogenous f a e c e s and f o r u r i n a r y  nitrogen losses.  The energy a s s o c i a t e d w i t h m e t a b o l i c f a e c e s (7) and  t h a t a s s o c i a t e d w i t h the u r i n e , c o r r e c t e d f o r endogenous n i t r o g e n , i s theoretically self-cancelling.  The c o n c l u s i o n i s t h a t the apparent  d i g e s t i b l e energy of the b a s a l r a t i o n i s approximately e q u a l to i t s metabolizable  energy.  57  When the b a s a l r a t i o n p l u s 20% or 14% added f i b r e was f e d to these mink, they g e n e r a l l y l o s t weight f o r t h e f i r s t on the second week they e i t h e r m a i n t a i n e d or even gained  week, but body weight,  d e s p i t e a s i g n i f i c a n t l y lower apparent d i g e s t i b l e energy i n t a k e when r e c e i v i n g the b a s a l r a t i o n . explanations  f o r these  than  There a r e s e v e r a l p o s s i b l e  observations:  (a) The i n i t i a l weight l o s s may be a s s o c i a t e d w i t h a l a c k of a c c e p t a b i l i t y of t h e r a t i o n supplemented w i t h h i g h f i b r e . i s n o t l i k e l y s i n c e the mink d i d n o t go o f f feed but i n f a c t  This increased  feed consumption on a u n i t weight b a s i s . (b) The mink may have become q u i e s c e n t and  thereby conserved energy.  during  the second week  T h i s was n o t apparent through  observations. (c) The d i s t e n t i o n of t h e gut may have o c c u r r e d therefore increased  g r a d u a l l y and  the mink's c a p a c i t y t o handle l a r g e r q u a n t i t i e s  of the feed concurrent  with a gradual  i n c r e a s e i n feed time o f  passage, thereby p e r m i t t i n g a l a r g e r i n t a k e o f feed per u n i t time. (d) The mink may have been a b l e t o u t i l i z e t h e heat increment of f e e d i n g , c a l l e d the s p e c i f i c dynamic a f f e c t , or S.D.A. ( 5 , 1 3 ) , which would be d i s s i p a t e d as waste heat w i t h i n the animal's comfort zone b u t u t i l i z e d w i t h d e c r e a s i n g mean d a i l y temperature d u r i n g  ambient temperatures.  S i n c e the  the p e r i o d when t h e animals r e c e i v e d  the b a s a l r a t i o n and the b a s a l r a t i o n p l u s the 20% added f i b r e was 10.7°C i n both cases,  t h i s c o u l d not have been a factor„  But i t  58  may  have been a f a c t o r when the mink r e c e i v e d the o t h e r  r a t i o n s when the temperature was (e) These o b s e r v a t i o n s  as low  two  as 2.7°C„  on the e f f e c t s of added d i e t a r y f i b r e  on the apparent economy of energy are i n agreement w i t h B i e l y Marsh (2) and w i t h McKenzie (18) , who  a t t r i b u t e s these  discrepancies  to the use of apparent d i g e s t i b l e energy, which does not account the i n c r e a s e i n m e t a b o l i c feed i n t a k e (30) , and  and  take i n t o  faeces a s s o c i a t e d w i t h i n c r e a s i n g  i n c r e a s i n g l e v e l s of d i e t a r y f i b r e  (19).  This  would tend to underestimate the t r u e energy i n t a k e of a mink and i s one  probable  e x p l a n a t i o n f o r the apparent c o n s e r v a t i o n of energy.  ( f ) A more l i k e l y e x p l a n a t i o n of the apparent decrease i n energy requirements w i t h  i n c r e a s i n g r a t i o n f i b r e by the mink may  be  the i n c r e a s e i n net energy, which c o u l d r e s u l t from a lower S.D.A. because of lower n u t r i e n t c o n c e n t r a t i o n s , p a r t i c u l a r l y p r o t e i n , at any  one  time r e l a t i v e to the h i g h c o n c e n t r a t i o n of n u t r i e n t s i n the  basal ration. decreasing  I t i s therefore postulated that concurrent  with  r a t i o n q u a l i t y , t h e r e i s a g r e a t e r i n c r e a s e i n the  energy than would be p r e d i c t e d on the b a s i s of the apparent energy of each r a t i o n , i n keeping w i t h  net  digestible  the law of d i m i n i s h i n g  returns  as o u t l i n e d i n d e t a i l by Brody ( 5 ) . These measurements r e l a t i n g apparent d i g e s t i b l e energy i n t a k e of the mink on the b a s a l r a t i o n without difficult  to compare w i t h other data  the l a c k of d e f i n e d c o n d i t i o n s .  (6, 10,  any weight change are  16,  25,  27)  Over the weight range  because of considered,  59  they do agree w e l l w i t h an e q u a t i o n f o r m u l a t e d by Wood and F a r r e l l (36) r e l a t i n g the apparent d i g e s t i b l e i energy o f a d u l t female mink a g a i n s t body weight.  T h i s d a t a has been c o l l e c t e d from many s o u r c e s .  Because o f the good agreement between the p r e s e n t measurements and those c a r r i e d out by Jorgensen  (11) d u r i n g a f o u r t e e n day  p e r i o d a t the end <5f October, i t i s a n t i c i p a t e d t h a t the standard curve r e p r e s e n t i n g the d a t a i n F i g u r e 2 may be u t i l i z e d as a b a s i s on which t o p r e d i c t the energy requirements o f female mink m a i n t a i n e d under p r a c t i c a l ranch c o n d i t i o n s d u r i n g the autumn.  60  BIBLIOGRAPHY 1.  B e n e d i c t , F.G. 1938. V i t a l e n e r g e t i c s . A study i n comparative b a s a l metabolism. C a r n e g i e I n s t . Wash. P u b l . No. 503.  2.  B i e l y , J . and B. March. 1961. Some h i g h l i g h t s o f n u t r i t i o n r e s e a r c h i n the p o u l t r y s c i e n c e department o f the U n i v e r s i t y o f B r i t i s h Columbia. F e e d s t u f f s . 33, (23), 26.  3.  B l a x t e r , K.L., F.W. Wainman, and J . L . Davidson. 1966. The v o l u n t a r y i n t a k e o f food by sheep and c a t t l e i n r e l a t i o n t o t h e i r energy requirements f o r maintenance. Animal Prod. .8_, 75-83.  4.  B r e n t , B.E., D. R i c h a r d s o n , W.S. T i e n and C.S. Menzies. 1961. D i g e s t i b i l i t y s t u d i e s on l e v e l s o f c o n c e n t r a t e s i n complete p e l l e t e d r a t i o n s f o r f a t t e n i n g lambs. J . Animal S c i . 20_, 526-528„  5.  Brody, S. New York.  6.  Ebner, K.E. 1955. S t u d i e s i n mink n u t r i t i o n w i t h s p e c i a l r e f e r e n c e to supplementary p r o t e i n s o u r c e s . Unpublished Master's t h e s i s , Dept. o f Animal S c i . , U n i v e r s i t y o f B r i t i s h Columbia.  7.  F a r r e l l , D.j.~. 1966 a. P a r t I I . S t u d i e s on the mink d u r i n g starvationI (Included i n t h i s t h e s i s ) .  8.  F a r r e l l , D.J. 1966 b . P a r t I I I . The e f f e c t s o f the a d d i t i o n o f f i b r e t o the r a t i o n . 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McKenzie, R„M. 1964, The response o f t h e l a b o r a t o r y r a t t o changes i n t h e c a l o r i c d e n s i t y and p r o t e i n : c a l o r i e r a t i o o f i t s r a t i o n . U n p u b l i s h e d M a s t e r ' s t h e s i s , Dept. o f A n i m a l S c i . , U n i v e r s i t y o f B r i t i s h Columbia,  19.  Meyer, J.H, 1956, I n f l u e n c e o f d i e t a r y f i b r e on m e t a b o l i c and endogenous n i t r o g e n e x c r e t i o n . J , N u t r i t i o n , 58, 493-500.  20.  M i l l e r , S,A„ and J.B. A l l i s o n . 1958, The d i e t a r y n i t r o g e n r e q u i r e m e n t s of t h e c a t . J . N u t r i t i o n , 64^ 493-500.  21.  M i t c h e l l , H.H. 1962. Comparative n u t r i t i o n o f man and d o m e s t i c a n i m a l s . V o l , I , Academic P r e s s , New Y o r k ,  22.  M o r r i s o n , F,B. 1959. Feeds and f e e d i n g . Co., C l i n t o n , Iowa,  23.  N a t i o n a l r e s e a r c h c o u n c i l , committee on a n i m a l n u t r i t i o n , U.S.A. 1953, N u t r i e n t r e q u i r e m e n t s f o r domestic a n i m a l s . 7, N u t r i e n t r e q u i r e m e n t s f o r f o x e s and minks, N a t , Acad. S c i e n c e : - N a t , Res. C o u n c i l , Washington, P u b l . No, 296.  24.  N o l a n d , P.R. and K,W. S c o t t . I960, E f f e c t o f v a r y i n g p r o t e i n and energy i n t a k e s on growth and c a r c a s s q u a l i t y o f swine, J , A n i m a l S c i , 19 67-74.  25.  N o r d f e l d t , S, 1947. ( S t u d i e s o f t h e f e e d consumption o f mink) Lantbrukshogsk„ H u s d j u r s f o r s o k s a n s t , S a r t r y c k Forhandsmedd No 62„ (as quoted i n N u t r . A b s t r . Rev. 1948, 18, 4 5 3 ) .  1961„  The f i r e o f l i f e .  W i l e y and Sons, I n c . New Y o r k .  22nd, e d , , M o r r i s o n P u b l i s h i n g  0  26.  Outko, J.A., R,E. W u t h i e r , and P . H . P h i l l i p s , 1957, The e f f e c t s o f i n c r e a s e d d i e t a r y f a t upon t h e p r o t e i n r e q u i r e m e n t o f t h e growing dog. J . N u t r i t i o n , 62_, 163-169.  62  27.  Palmer, L.S. 1927 - 28, D i e t i c s and i t s r e l a t i o n t o f u r p r o d u c t i o n . Amer.-Fox and Fur Farmer, 7_, 22; 3_, 18.  28.  P e r e l ' d i k , M.N. and M.I. T i t o v a . 1950. ( E x p e r i m e n t a l d e t e r m i n a t i o n o f f e e d i n g standards f o r a d u l t b r e e d i n g mink) K a r a k u l . Z v e r . 3, No. 2, 29. (As quoted by A i t k e n , F.C. 1953. Feeding o f f u r - b e a r i n g a n i m a l s , T e c h n i c a l Communication No. 23 Aberdeen: Commonwealth Bureau o f A n i m a l Nutrition.  29.  P e t e r s o n , D.W., C.R. Gran, and N.F. Peek. 1954. Growth and food consumption i n r e l a t i o n t o d i e t a r y l e v e l s o f p r o t e i n and f i b r o u s b u l k . J . N u t r i t i o n , 5 2 , 241-257.  30.  S c h n e i d e r , B.H. 1935. The r e l a t i o n s h i p o f m e t a b o l i c n i t r o g e n . i n t h e f a e c e s o f t h e r a t , swine and man. Biochem. J , 28, ,360.  31.  S i b b a l d , I.R., R.T. B e r g , and J.P. Bowland. 1956. D i g e s t i b l e energy i n r e l a t i o n t o food i n t a k e and n i t r o g e n r e t e n t i o n i n t h e weanling r a t . J . N u t r i t i o n , 5 9 , 385-392.  32.  S i b b a l d , I.R., D.G. S i n c l a i r , E.V.Evans, and D.L.T.Smith. 1962. The r a t e o f passage o f feed through t h e d i g e s t i v e t r a c t o f t h e mink. Can. J . Biochem. and P h y s i o l . 40, 1391-1394.  33.  S i n c l a i r , D.G., E.V.Evans, and I . R . S i b b a l d . 1962. The i n f l u e n c e apparent d i g e s t i b l e .energy and apparent d i g e s t i b l e n i t r o g e n i n t h e d i e t on weight g a i n , feed consumption,.and n i t r o g e n r e t e n t i o n o f growing mink. Can. J . Biochem. and P h y s i o l . 40_, 1375-1389.  34.  S i n c l a i r , D.G, and E.V.Evans. 1962. A metabolism cage designed f o r use w i t h mink. Can. J . Biochem and P h y s i o l . 40_, 13.95-1399.  35.  Wishnofsky, M. 1958. C a l o r i c e q u i v a l e n t s o f gained o r l o s t w e i g h t . Am. J . C l i n . N u t r i t i o n , 6_ 542-546.  Nitrogen  s  36.  Wood, A . J . and D.J. F a r r e l l , 1965. Some o b s e r v a t i o n s , on mink n u t r i t i o n . West. Fur Farmer, j4, ( 8 ) , 12,  37.  Wood, A . J .  1956. The b l a c k f o x magazine and modern>mink b r e e d e r .  39, ( 1 ) , 12.  THE  NUTRITION OF THE FEMALE PASTEL MINK (Mustela  PART  V:  WATER REQUIREMENTS FOR MAINTENANCE  vlson)  63  INTRODUCTION  Even under c o n t r o l l e d c o n d i t i o n s , the task o f measuring the water r e q u i r e m e n t s o f a s p e c i e s over a r e l a t i v e l y l o n g p e r i o d o f time p r e s e n t s many problems.  One o f these I s the measurement o f the water  a s s o c i a t e d w i t h a change i n body c o m p o s i t i o n , which may o r may not occur w i t h a change i n body weight.  Presenting similar d i f f i c u l t i e s  i s the  measurement o f the m e t a b o l i c water o r water o f o x i d a t i o n o f the f e e d . S e v e r a l e q u a t i o n s have been formulated  (12,16,18) which attempt t o  c o r r e c t f o r the above and o t h e r v a r i a b l e s by u t i l i z i n g  s e v e r a l paramaters  which would be extremely d i f f i c u l t t o c o n t r o l and measure i n the mink for  a l e n g t h y p e r i o d under maintenance  conditions.  Of p r a c t i c a l s i g n i f i c a n c e i s the measurement o f the t o t a l water i n t a k e by a s p e c i e s under n o n - s t r e s s c o n d i t i o n s and the r e l a t i o n of  t h i s d a t a t o some parameter which w i l l p e r m i t a comparison w i t h the  water i n t a k e o f o t h e r s p e c i e s .  Richter  (19) and Adolph (1) have  expressed water requirements per C a l o r i e o f heat produced, t h e r e b y i m p l y i n g t h a t the dominant r o l e o f water i n the animal i s c l o s e l y r e l a t e d t o the heat produced by the system. Many f a c t o r s can change the water r e q u i r e m e n t s o f a s p e c i e s , such as temperature (2,5), s a l t s i n the feed adaptation  (20), t o name but a few.  (10), as w e l l as p h y s i o l o g i c a l  The o b j e c t o f t h i s experiment i s the  a c c u r a t e measurement o f water consumption by the mink under n o n - s t r e s s c o n d i t i o n s , s i n c e no such datum i s a v a i l a b l e f o r t h i s  species.  64  EXPERIMENTAL Because water i n t a k e was measured c o n c u r r e n t s t u d i e s , d e t a i l s of animals, i d e n t i c a l t o those  housing,  w i t h feed  intake  n u t r i t i o n and management a r e  o u t l i n e d i n t h a t study ( 8 ) .  S p e c i a l Equipment For each mink, water was p r o v i d e d  ad l i b i t u m from an i n v e r t e d  four-ounce b o t t l e c l o s e d by a one-hole No. 8 rubber stopper was  i n s e r t e d a s t r a i g h t l e n g t h o f Pyrex g l a s s t u b i n g .  through which  By means o f a s t r o n g  rubber band, the b o t t l e was f a s t e n e d onto a s t r i p o f m e t a l b o l t e d a t e i t h e r end  to wall brackets.  mesh o f the cage r o o f . v i b r a t i o n s i n the cage.  The water b o t t l e tube was i n s e r t e d through the w i r e The b o t t l e was t h e r e f o r e independent o f any Any d r i p s from the b o t t l e were c o l l e c t e d i r i m i n e r a l  o i l p l a c e d i n a m e t a l c o n t a i n e r d i r e c t l y below the g l a s s t u b i n g o u t l e t . T h i s c o n t a i n e r s a t on the aluminum t r a y beneath the cage. Feed  Moisture T r i p l i c a t e feed samples were d r i e d a t 100° C t o a c o n s t a n t  i n order feeders  t o determine t h e i r m o i s t u r e c o n t e n t .  weight  Because o f the s p e c i a l mink  (21) and because the mink were f e d t h r i c e d a i l y , e v a p o r a t i v e  losses  o f m o i s t u r e from the feed were c o n s i d e r e d  t o be n e g l i g i b l e .  was  the s m a l l q u a n t i t i e s o f waste feed  made f o r the m o i s t u r e a s s o c i a t e d w i t h  collected  daily.  Metabolic  Water A c o r r e c t i o n has been' made f o r the m e t a b o l i c  with  the f e e d , by u t i l i z i n g  equations  the c o e f f i c i e n t s o b t a i n e d  o f t y p i c a l p r o t e i n s , f a t s and  carbohydrates.  A correction  water a s s o c i a t e d  from the o x i d a t i o n  65  RESULTS The r e l a t i o n s h i p between  total"*" water i n t a k e and apparent  d i g e s t i b l e energy ( A D E . ) i n C a l o r i e s f o r those mink r e c e i v i n g t h e b a s a l 0  0  2 r a t i o n and housed i n ranch-type cages i s p r e s e n t e d i n F i g . 1. i n t a k e , when r e l a t e d t o bodyweight  The water  ( F i g . 2) shows a poor c o r r e l a t i o n  But when o n l y those animals a r e i n c l u d e d t h a t showed no weight (- 10 gm) a r e i n c l u d e d , a h i g h c o r r e l a t i o n two  (r=0.278).  fluctuations  (r=0.901) e x i s t s between these  variables. When f i b r e was added t o t h e b a s a l r a t i o n , t h e r e was a s i g n i f i c a n t  increase  (t=.01) i n the t o t a l water i n t a k e when expressed on a p e r  c a l o r i e b a s i s , but was about t h e same when expressed on a d r y matter intake basis  (2.80 gm water/gm d r y m a t t e r ) .  When t h e mink were on t h e  h i g h e s t f i b r e r a t i o n , they consumed more water (t=.01) than when they r e c e i v e d t h e o t h e r two r a t i o n s w i t h l e s s added  fibre.  DISCUSSION The c o n s i s t e n t r e l a t i o n s h i p between  the energy (A.D„E„) o f  the feed and water i n t a k e suggests t h a t on the b a s a l r a t i o n the mink consumed 0.68 gm o f t o t a l water p e r C a l o r i e  (A„D.E„) o f b a s a l  ration  and somewhat more (0„77 gm/Calorie) when f i b r e was added t o t h e b a s a l ration.  I t i s , however, p o s s i b l e t h a t these two f i g u r e s may agree i f  the water i n t a k e were expressed on a n e t energy b a s i s .  The r e l a t i o n s h i p  i s i n good agreement w i t h t h e f i g u r e o f 0.78 c a l c u l a t e d from water i n t a k e and feed i n t a k e data f o r the c a t (7) and t h e f i g u r e o f 0.61 f o r the mouse ( 1 7 ) .  Adolph (1) has concluded t h a t under n o n - s t r e s s  lo T o t a l water intake=the summation o f feed water, m e t a b o l i c water and b o t t l e water, 2„ Water intake=the summation o f feed water and b o t t l e water o n l y .  FIGURE 1: THE RELATIONSHIP BETWEEN TOTAL WATER AND APPARENT DIGESTIBLE ENERGY INTAKE OF MINK RECEIVING THE BASAL RATION HOUSED IN RANCH-STYLE  AND CAGES  150  O  O  o 100  o  o y  = 0.442x + 40.8  S R  = 5.7  r  = 0.622 f o r 43df  50  170  190  210  APPARENT DIGESTIBLE ENERGY, C a l o r i e s  230  250  FIGURE 2: THE RELATIONSHIP BETWEEN WATER INTAKE AND BODYWEIGHT OF MINK RECEIVING THE BASAL RATION AND HOUSED IN RANCH-STYLE  CAGES  150  BODYWEIGHT, grams  FIGURE 3: THE RELATIONSHIP BETWEEN WATER INTAKE AND BODYWEIGHT OF MINK RECEIVING THE BASAL RATION, HOUSED IN RANCH-STYLE CAGES, AND DEMONSTRATING WEIGHT STASIS  WATER INTAKE, grams o o  o  <J1  o  >  o o  >  0  o  00 H  o o  CO  > rt II  O  •  o  <J5 O  II  •  II  >  o  *  o t-  1  or  Hi  CO  +  vO CX rh  OJ • On  69  conditions  the v o l u n t a r y consumption f o r a l l mammals i s 1 gm  per C a l o r i e . steers  and  Mitchell  has  (15)  has  Bell  (14)  of 1.01  gm/  gm  of water per  Benedict's  (4)  a s i m i l a r f i g u r e has  per  been  figure for a fasting  the mean t o t a l water i n t a k e  e l e v e n female mink r e c e i v i n g h i g h energy s y n t h e t i c gm  by  man  C a l o r i e of heat produced. I t i s worthy of note t h a t  0.52  of  Calorie,  gm/gross C a l o r i e r e p o r t e d  f o r l a c t a t i n g cows and  measured f o r the monkey (23). i s 0.81  d a t a on water i n t a k e  o b t a i n e d a mean f i g u r e of 1.21  i n c l o s e agreement w i t h t h a t Macdonald and  recalculated  of water  calculated  Calorie  levels, calculated  from the  l e s s than 0.4%  the  and  ash  r a t i o n s , fed d r y ,  (A.D.E.) ( u n p u b l i s h e d ) .  c o m p o s i t i o n of the c o n t e n t s d i d not  of  The  fibre  ration ingredients  exceed 6%  was  on a dry  were  weight  basis. Richter this varied  (19)  has  between 1050  c a t s , monkeys and  gm  humans.  any  degree of p r e c i s i o n .  the  l i v e mink, and  intake  and  1238  gm  per  This  not  to measure w i t h i n the  case  of  been used as a b a s i s  on  intake.  h i g h c o r r e l a t i o n between dry matter consumed and  ( F i g , 3) d u r i n g weight s t a s i s i s i n c o n t r a s t  weight s t a s i s i s feed  area,  sq. meter f o r dogs, r a t s ,  i s p a r t i c u l a r l y true  o b t a i n e d d u r i n g weight f l u c t u a t i o n s . i T h i s  intake.  to body s u r f a c e  S u r f a c e area i s d i f f i c u l t  f o r t h i s r e a s o n , i t has  which to express water The  r e l a t e d water i n t a k e  intake  domestic a n i m a l s , L e i t c h and  suggests t h a t  a good base a g a i n s t  N e v e r t h e l e s s , i t i s the  one  to the  low  correlation  only during  which to r e l a t e water  which i s most g e n e r a l l y  Thomson (13)  water  used  for  have r e p o r t e d r a t i o s of  2:1  f o r sheep and  3:1  f o r horses  bacon p i g s showed l i t t l e l b . of feed.  and  pigs.  Holine  (11) has  e f f e c t when l i m i t e d to 1:5  P r o v i s i o n o f an u n r e s t r i c t e d supply  reported  that  l b s of water per  of water i n a d d i t i o n  to the allowance of 1% l b added to each l b of meal, r e s u l t e d i n a marked improvement i n the d a i l y feed consumption and weight g a i n  (3).  The  f i g u r e of 2.8:1  f o r the c a t  i n the r a t e of  (7) i s i d e n t i c a l  to t h a t measured f o r the mink, but much h i g h e r than f o r the mouse ( 3 ) , when a f i g u r e of o n l y 1.3:1  has  been  obtained.  The mere f a c t t h a t the average water i n t a k e per gram of dry feed i n g e s t e d was  the same on the b a s a l and  r a t i o n s suggests t h a t w i t h d e c r e a s i n g content with  of the faeces decreased  on the added  r a t i o n d i g e s t i b i l i t y the water  s i n c e the f a e c a l output  increasing dietary fibre levels.  fibre  increases  T h i s , then, tends to oppose a  theory which attempts to e x p l a i n the i n v e r s e r e l a t i o n s h i p between the time of passage of the feed and  ration fibre level  ( 9 ) , u n l e s s water  i s withdrawn from the faeces i n the l a r g e i n t e s t i n e . From the water measurements c a r r i e d out on these mink, i t may  be concluded  t h a t the water i n t a k e of a 900  weight s t a s i s i s 110.2  gm per day,  gm mink demonstrating  u s i n g the e q u a t i o n  from F i g . 3.  Based on the c a l c u l a t e d A.D.E. i n t a k e f o r the same mink (8) and the e q u a t i o n  r e l a t i n g water to energy  i n t a k e would be  117.4  gm per  day.  using  (A.D.E.) i n F i g . 1, the water  71  BIBLIOGRAPHY 1.  Adolph, E.F. 1933, The metabolism and d i s t r i b u t i o n o f water i n body and t i s s u e s . P h y s i o l , Revs. 13_, 336-371.  2.  B a i l e y , C,B. 1964, E f f e c t of e n v i r o n m e n t a l temperature on f e e d , d i g e s t i o n , water metabolism, body temperature and c e r t a i n b l o o d c h a r a c t e r i s t i c s o f sheep. Can, J . Animal S c i . 44, 68-75.  3.  Barber, R.S., R. Braude, and K . G . M i t c h e l l , 1963. Further s t u d i e s on the water requirements o f the growing p i g . Animal Prod. 5_, 277-282,  4.  B e n e d i c t , F.G. 1915, A s t u d y o f prolonged f a s t i n g . I n s t . Wash. P u b l . No. 203.  5.  B e n e d i c t , F.G. 1923. Under n u t r i t i o n i n s t e e r s . I n s t . Wash. P u b l . No. 203.  6.  B i n g , F.G. 1923. and L.B. Mendel. 1931. The r e l a t i o n s h i p between food and water i n t a k e i n mice. Am. J . P h y s i o l . 169-179.  Carnegie  Carnegie  98,  7.  C a r v e r , D.S. and H.N. Waterhouse. water consumption of c a t s .  1962. The v a r i a t i o n i n the P r o c . Animal Care P a n e l 12_, 267-270.  8.  F a r r e l l , D. J . 1966. P a r t IV. Energy requirements f o r maintenance. (Included i n t h i s t h e s i s ) .  9.  F a r r e l l , D.J. 1966. P a r t I I I . The e f f e c t s o f the a d d i t i o n o f f i b r e to the r a t i o n . (Included i n t h i s t h e s i s ) .  10.  Gamble, J . L . , M.C. Putnam, and C.F. McKhaun. 1929. The o p t i m a l water requirements i n r e n a l f u n c t i o n . I . Measurements o f water d r i n k i n g by r a t s a c c o r d i n g to increments o f u r e a and of s e v e r a l s a l t s i n the f o o d . Am. J . P h y s i o l . 88_, 571-580.  11.  H o l i n e , D.W. and K.L. Robinson. 1965. A study o f water allowance f o r bacon p i g s . Animal Prod, 7_, 377-384,  12.  L a v i e t e s , P.H. 1935. The m e t a b o l i c measurement o f water J . C l i n . I n v e s t . 14, 57-69.  13.  L e i t c h , I . and J.S. Thomson. 1944. The water economy o f farm a n i m a l s . N u t r i t i o n A b s t r . Revs. 14, 197-223.  exchange.  72  14.  MacDonald, M.A. and J.M. B e l l . 1958. E f f e c t s o f low f l u c t u a t i n g temperatures on farm a n i m a l s : I I . I n f l u e n c e o f ambient a i r temperature on water i n t a k e o f l a c t a t i n g H o l s t e i n - F r i e s i a n cows. Can. J . Anim. S c i . 38_, 23-32.  15.  M i t c h e l l , H.H. 1962. Comparative n u t r i t i o n o f man and domestic a n i m a l s . V o l . I . Academic P r e s s , New York.  16.  Newburgh, L . H „ , M.W. Johnston, and F a l c o n - L e e v e s . 1930. Measurements o f t o t a l water exchange. J . C l i n . I n v e s t . 8^, 161-166.  17.  Nishimura, T.  18.  P e t e r s , J.P., D.M. K y d e l , and P.H. L a v i e t e s . A note on t h e c a l c u l a t i o n o f water exchange. J . C l i n . I n v e s t . 12_, 689-693.  19.  R i c h t e r , C P . 1938. F a c t o r s d e t e r m i n i n g v o l u n t a r y water i n g e s t i o n i n normals and i n i n d i v i d u a l s w i t h maximum d i a b e t e s i n s i p i d u s . Am. J . P h y s i o l . 122, 668-675.  20.  S c h m i d t - N i e l s e n , K. and B. S c h m i d t - N i e l s e n . 1952. Water i n d e s e r t mammals. P h y s i o l . Revs. 32_, 135-166.  21.  S i n c l a i r , D.G. and E.V. Evans. 1962. A metabolism cage designed f o r use w i t h mink. Can. J . Biochem. and P h y s i o l . 40_, 1395-1399.  22.  Wayner, M.J.  23.  Wood, A . J . and M.A. Kennard. 1956. The f e e d i n g , housing and management o f a s m a l l monkey c o l o n y . Can, J . Comp. Med. 20, 294-301.  1966. P e r s o n a l communication.  0  1964. T h i r s t .  metabolism  The M a c m i l l a n Pub. Co., New York.  APPENDICES  73  APPENDIX I AN INDIRECT ANIMAL CALORIMETER FOR MINK  INTRODUCTION  An e f f e c t i v e c a l o r i m e t e r must p r o v i d e  f o r the study o f mink metabolism  an animal chamber of s u f f i c i e n t  s i z e t o permit the mink  to l i v e w i t h i n the chamber f o r p r o l o n g e d p e r i o d s .  E x p e r i e n c e has  shown t h a t a l o n g p e r i o d o f t r a i n i n g i n the c a l o r i m e t e r if  i s essential  the mink i s t o be persuaded t o remain i n a s t a t e o f complete r e s t  for periods of m e t a b o l i c  of s u f f i c i e n t d u r a t i o n t o a l l o w the a c c u r a t e  measurements  rate.  PRINCIPLE The c a l o r i m e t e r developed t o meet t h i s requirement i s o f the closed c i r c u i t volumetric  type.  The carbon d i o x i d e produced by the  a n i m a l i s absorbed by an a g i t a t e d sodium h y d r o x i d e s o l u t i o n . consumed by the animal i s r e p l a c e d aid of a pressure-sensing  Oxygen  through a m e t e r i n g d e v i c e w i t h  the  manostat.  DESCRIPTION OF THE CALORIMETER A schematic r e p r e s e n t a t i o n o f the b a s i c d e s i g n c a l o r i m e t e r i s shown i n F i g u r e 1.  The p e r t i n e n t r e g u l a t o r y  are enumerated i n the f i g u r e a c c o r d i n g 1.  f e a t u r e s o f the devices  t o the f o l l o w i n g sequence:  A c y l i n d e r o f oxygen ( A ) , (99.6% minimal oxygen c o n t e n t ) w i t h the  usual pressure  regulators.  FIGURE I : A DIAGRAMMATIC REPRESENTATION OF THE RESPIROMETER  2.  A solenoid valve  (N)  to c o n t r o l oxygen f l o w from the open p r e s s u r e  r e g u l a t o r t o the animal chamber, 2 3.  A p r o p o r t i o n a l flow c o n t r o l l e r  ( L ) t o a c t i v a t e the power c i r c u i t  to the s o l e n o i d v a l v e . 3 4.  A p r e - c a l i b r a t e d wet  t e s t gas meter  (K) to measure the volume o f  oxygen consumed. 5.  A water manometer (H) t o sense changes i n p r e s s u r e i n the animal  chamber.  C l i p p e d t o the manometer i s a s e n s i n g probe to t r a n s m i t  p r e s s u r e changes from the manometer to the p r o p o r t i o n a l 4 6.  An a n a e r o b i c i n c u b a t o r  animal chamber (30 cm 7.  controller.  (E) to s e r v e as a temperature r e g u l a t e d  x 30 cm  x48  cm ) .  A t h e r m a l l y r e g u l a t e d water bath"* (g) to p r o v i d e a r e s e r v o i r o f  e t h y l e n e g l y c o l , of known temperature exchange c o i l - f a n system  f o r c i r c u l a t i o n through the heat  (G) mounted i n the back w a l l o f the a n i m a l  chamber. 8.  Two  t h e r m i s t o r s w i t h i n the animal chamber to determine the 6 temperature by means o f an e x t e r n a l tele-thermometer (M). 1.  C o n t r o l Co. of Canada, C o o k v i l l e , O n t a r i o .  2.  Matheson o f Canada, L t d . , Whitby, O n t a r i o .  3.  P r e c i s i o n S c i e n t i f i c Co.,  4.  N a t i o n a l A p p l i a n c e Co., P o r t l a n d 23, Oregon.  5.  E. H. Sargent & Co.,  6.  Y e l l o w s t o n e Instrument  Chicago,  Chicago,  Illinois.  Illinois.  Co., Y e l l o w s t o n e , Ohio.  interior  9„  A p o l y e t h y l e n e c e n t r i f u g a l pump  (D) f o r c i r c u l a t i o n o f thecarbon  d i o x i d e a b s o r b i n g potassium h y d r o x i d e s o l u t i o n c o n t a i n e d i n a s h a l l o w pyrex d i s h  (4.4 cm x 22 cm x. 27 cm) r e s t i n g below the animal cage  w i t h i n t h e chamber. 10. A r e c t a n g u l a r cage (18 cm x 25 cm x 30 cm) o f 2.5 cm square mesh g a l v a n i z e d 12 gauge i s mounted on a metal droppings pan (F) p r o v i d e d w i t h a removable t r a y . OPERATION OF THE CALORIMETER The animal under study i s admitted t o t h e w i r e cage and then p l a c e d i n t h e r e s p i r o m e t e r chamber.  The chamber door i s l e f t  a j a r and t h e c i r c u l a t i n g f a n o f the h e a t i n g / c o o l i n g u n i t i s a l l o w e d to  run continually.  The animal i s f e d and watered  chamber f o r a p r o l o n g e d p e r i o d  w i t h i n the  (2-3 weeks) t o permit i t t o a d j u s t t o  the e x p e r i m e n t a l c o n d i t i o n s . The  s i n g u l a r l a c k o f m e t a b o l i c r a t e measurements on t h i s  semi-domesticated  animal i s i n d i c a t i v e o f t h e g r e a t d i f f i c u l t y i n  o b t a i n i n g a q u i e s c e n t s t a t e f o r a p e r i o d o f time s u f f i c i e n t t o o b t a i n meaningful data. To measure t h e oxygen consumption  o f the a n i m a l , a t e n  p e r c e n t s o l u t i o n o f potassium h y d r o x i d e i s i n t r o d u c e d i n t o t h e pyrex d i s h and i s m a i n t a i n e d i n an a g i t a t e d c o n d i t i o n by t h e p o l y e t h y l e n e c i r c u l a t i n g pump. 1.  Temperature c o n t r o l i s m a i n t a i n e d by c i r c u l a t i n g  Cole-Parmer  Instrument  & Equipment Co., Chicago 10, I l l i n o i s  77  e t h y l e n e g l y c o l from the t h e r m a l l y r e g u l a t e d r e s e r v o i r through the heat exchange c o i l .  The animal i s observed u n t i l i t i s a s l e e p .  At  t h i s time, the door o f the chamber i s c l o s e d , p r e s s u r e w i t h i n the chamber i s a d j u s t e d to the ambient  b a r o m e t r i c p r e s s u r e , and the  manostat-sensing p r o b e - p r e s s u r e c o n t r o l l e d system i s a c t i v a t e d t o m a i n t a i n a c o n s t a n t p r e s s u r e w i t h i n the system through the measured a d d i t i o n o f oxygen from the oxygen c y l i n d e r . absorbed c o n t i n a l l y i n the a g i t a t e d KOH  The carbon d i o x i d e i s  solution.  The animal i s observed through the window i n the chamber door. the  The oxygen consumption  i s measured over the p e r i o d d u r i n g which  animal i s asleep. A f t e r c o n v e r s i o n to s t a n d a r d c o n d i t i o n s , the oxygen  consumption  v a l u e s a r e c o n v e r t e d to c a l o r i c e q u i v a l e n t s on the assumption  t h a t the  i s 0.8  Calories.  and the thermal e q u i v a l e n t per l i t r e  o f oxygen i s 4.80  R.Q.  APPENDIX I I Mink C e r e a l G r a i n  Pellets  Amounts ( l b s )  Ingredients • Tomato Pomace  100  Ground Wheat  590  Wheat Bran  100 65  Wheat Germ Meal  150  Oat Groats F i s h Meal  200  (70%)  Soya Meal (50%)  200  L i n s e e d O i l Meal  100  A l f a l f a L e a f Meal  100  Skim M i l k Powder  100  Brewer's Yeast  20  Steamed Bone Meal  20  Iodized  5  Salt  Molasses - Cane  100  S t a b i l i z e d Fat  150  Dry V i t a m i n A - 1,000,000 I.U. Dry V i t a m i n D -  150,000 I.U.  2,000  APPENDIX I I I I n d i v i d u a l Weight Records (grams) of C o n t r o l s *  Animal  Adult: Barren Female i P a s t e l s AP2 API AP3  Adult F e r t i l e Female P a s t e l s AP4 AP6 AP5  Female Standard Darks AB7 AB8 AB3  Week 0  668  573  765  3  704  574  784  729  634  7  775  587  763  787  11  818  610  747  837  915  605  830  609  919  702  799  705  690  1047  785  1065  737  810  1081  760  1105  *Mink m a i n t a i n e d on r a n c h operated by:  A. Peace, 4175 Douglas S t . , V i c t o r i a ,  B.C.  APPENDIX IV I n d i v i d u a l Weekly Weight Records  (grams)  Animal  PI  P2  P3  P4  P5  P6  Week 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15  823 864 851 862 890 858 858 822 835 804 805 852 860 878 870 860 787 838 835 837  792 747 756 727 750 751 746 746 748 685 706 746 743 736 732 749 683 718 726 747  822 785 765 795 828 830 833 832 849 841 849 907 922 913 914 876 810 874 926 920  866 819 827  661 719 681  700 631 606  699 740 745 744 741 702 668 642 655  558 667 691 698 726 690 698 654 716 700 702 706 634 706 735 737  *  16 17 18  *  650 697 649  Commencement o f second p e r i o d .  81  APPENDIX V I n d i v i d u a l D a i l y Feed Intake Records  Mink No. Day 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35  PI 55.2 65.1 51.3 41.9 51.7 47.2 44.1 53.5 31.3 35.4 34.4 47.0 .45.2 45.6 41.8 62.6 49.3 56.7 53.4 45.5 45.1 42.5 50.8 49.8 40.0 48.4 56.4 57.2 47.4 44.4 45.9 45.7 44.4 44.8 46.2  P2  49.3 33.7 40.5 49.6 34.4 44.7 50.4 40.9 32.1 37.2 42.1 41.9 43.4 42.5 49.5 41.5 44.2 J6 . > 23.2 36.3 33.1 40.6 40.4 34.9 54.9 52.3: 41.1 34.7 37.3 38.2 37.4 38.8 39.2  (grams)  P3  P4  P5  56.4 50.9 37.6 65.6 46.1  50.3 46.4 42.6 38.1 32.7 48.8 43.6 37.6 49.2 42.8 36.2 36.2 35.4 37.7 45.5 45.3 30.9 32.6 26.9  61.1 60.3 56.9  48.7 50.0 45.9 58.2 51.4 44.9  48.4 50.7 55.2 51.4 55.4 55.1  42.8  46.3 56.2 57.3 54.2 46.5  44.3 46.8 25.9  Basal 53.2 62.2 45.3 47.4 41.1  28.7 46.6 43.3 46.7 47.4 50.9 60.3 44.8 44.7 47.8 41.0 45.0 47.0 46.2  Ration  82  APPENDIX V  Mink No, Day 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70  PI  P2  58.7 47.1 45.7 48.5 46.8 50.3 51.1 49.2 50.0 46.6 46.6 48.2 47.7 43.4 51.9 50.4 53.5 54.4 53.7 49.6 52.7 39.7 53.0 46.7 49.4 51.7 46.5 46.5 60.7 58.1 60.8 61.7 62.4 57.0 55.6  48.5 38.5 34.8 39.6 39.4 40.8 41.5 44.0 43.3 39.9 38.4 38.4 40.5 39.2 42.9 44.3 44.2 39.3 43.9 39.9 hi. .o  48.6 55.2 57.4 51.9 65.1 60.3 57.0 45.2 49.1 54.9 56.4 54.0 54.0 55.7  (cont'd)  P3 41.9 42.0 46.3 47.7 47.8 47.9 48.6 47.6 50.7 47.3 48.9 47.6 42.1 42.7 46.4 46.1 48.0 46.6 46.5 47.8 47.9 . 46.4 52.1 54.8 54.1 56.7 56.5 59.3 55.7 58.5 63.0 54.4 67.2 56.3 54.9  P4  P5  51.1 41.3 41.8 42.6 38.7 42.5 37.1 42.7 33.6 46.4 43.3 44.6 40.4 39.3 43.2 34.1 42.3 45.2 48.6 40.3 36.9 41.9 23.6 49.2 39.7 44.6 47.8 52.2 36.1 40.2 33.4 40.6 45.7 35.9 43.5  48.4 35.8 39.2 44.1 45.1 38.9 41.2 43.4 43.2 41.5 39.8 41.3 41.9 41.8 42.4 41.6 41.9 44.1 43.0 44.0 45.9 48.2 42.0 46.4 47.4 51.9 52.6 52.5 48.2 55.3 49.4 58.7 57.1 54.5 49.1  Ration  Basal  Basal+20  83  APPENDIX V (cont'd)  Mink No.  Day  71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105  PI  P2  P3  51.1 59.8 47.7 63.6 55.8 54.5 56.5 58.0 55.4 57.6 48.8 48.5 48.9 54.0 46.6 51.0 53.2 54.9 43.3 47.8 56.4 48.5 54.1 53.0 52.3 52.5 55.4 49.2 52.0 51.7 50.5 55.2 59.1 58.4 53.6  47.1 50.5 56.8 61.2 47.0 53.4 47.8 47.5 47.9 54.9 53.3 45.7 36.6 44.3 41.6 43.6 45.6 48.9 42.9 41.1 45.3 48.3 50.4 48.9 57.7 45.8 44.4 47.7 44.5 48.7 47.4 53.2 55.7 56.3 46.9  50.0 56.8 65.5 58.5 54.2 51.7 59.3 51.1 54.3 58.4 55.2 35.1 43.6 47.2 37.0 47.3 52.6 50.6 48.7 53.0 i- ~ • ' <  J-> . X  49.9 54.6 51.1 52.4 44.5 41.3 57.7 53.6 46.9 50.9 56.7 56.6 48.8 51.5  P4  P5  46. a 49.6 48.9 38.6 43.5 48.6 33.4 38.6 33.6  57.9 55.1 56.3 50.9 52.4 52.3 52.0 34.9 41.4 39.5 42.9 46.7 49.7 45.2 43.6 73.6 49.5 53.7 50.1 55.3 49.6 51.2 52.9 54.5 49.9 49.7 56.4 58.7 46.0 49.8  Ration  Basal  Basal+14  84  APPENDIX V  Mink Day 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126  (cont'd)  No. PI  P2  P3  50.4 62.9 58.3 60.0 63.7 68.9 55.6 43.0 55.4 24.1 46.9 51.8 48.5 37.9 44.6 51.0 54.9 46.2 51.6 46.1 49.5  49.4 53.1 53.1 47.3 54.7 46.8 51.8 47.5 50.9 33.6 53.1 49.1 45.9 33.4 42.9 47.2 46.9 46.0 47.5 38.4 43.2  55.4 54.1 59.9 64.9 64.6 65.1 64.8 69.1 65.3 51.2 60.3 61.9 53.2 69.9 49.2 54.7 50.3 44.8 44.7 31.5 48.6  P4  P5  44.9 44.7 47.2 51.6 44.8 45.9 50.6 40.7 44.5 43.5 47.7 47.8 43.0 44.6  58.8 58.0 60.0 53.5 54.3 55.4 57.6 49.9 57.7 31.9 58.4 54.1 53.0 40.3 51.6 49.9 49.5 42.8 54.1 36.5 44.1  Ration A  Basal+7  X  Basal  V  APPENDIX VI D a i l y Feed (Dry) Intake And Mean Body Weight Of Mink During D i g e s t i b i l i t y  Mink No.  Feed Intake (grams)  Trials  i n M e t a b o l i s m Cages  Mean Body Weight (grains)  Ration  P4 P5 P6  39.2 36.7 47.4  804 721 650  Basal Basal Basal  PI P2 P5  39.1 35.7 33.9  813 711 722  Basal Basal Basal  PI P2 P5  35.0 38.2 33.0  822 703 701  Basal+7 Basal+7 Basal+7  PI P2 P3  66.6 47.7 55.1  844 729 689  Basal+14 Basal+14 Basal+14  P4 P5  49.0 56.1  660 694  Basal+20 Basal+20  APPENDIX V I I Mean Net D a i l y Water Intake f o r Each Week (grams)  1  Mink No. Week 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  PI 122.2 95.0 125.4 144.0 103.0 106.3 111.6 120.1 103.7 133.5 126.6 120.3 126.2 112.9 116.1 137.2 103.4 120.3  P2 78.9 84.8 91.5 101.0 87.5 95.4 94.8 107.9 131.8 124.8 125.4 116.1 89.0 113.0 113.7 117.7 111.7 115.9  P3 88.4 112.5 109.4 95.6 105.6 102.5 108.9 111.7 119.9 119.9 113.3 110.3 110.0 116.6 146.1 152.3 122.0  P4  P5  100.1 93.0  103.8  113.6 106.8 116.8 105.4 97.2 95.4  108.5 78.3 83.2 86.6 85.6 98.7  101.2  111.9 99.3 111.3 118.9 133.8 119.1 116.3  123.4 129.5  1  87  APPENDIX ¥111 I n d i v i d u a l Weekly Weigh-back Of Feed  Animal Week  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18  PI 15.3 10.1 6.2 2.2 6.4 11.8 7.4 9.6 17.7 19.9 12.9 10.8 9.4 8.1 9.0 13.7 4.6 15.9  P2 15.0 12.7 4.0 2.3 2.3 3.5 4.5 5.4 55.0 23.5 8.3 8.0 9.0 11.8 15.5 7.4 20.5 6.4  P3  8.8 16.5 15.4 16.5 9.6 7.0 50.1 26.6 15.0 12.2 11.5 19.9 17.3 14.1 10.4 7.3  P4  (grams)  P5  51.0 43.9 13.9  15.5  16.0 8.1 8.1 15.4 30.4 23.0 4.6 11.4  8.8 17.3 13.3 9.4 28.8 26.6 4.6 7.9 10.3 21.9 19.1 7.5 6.8 13.0  31.7 15.0  5.0  88  APPENDIX IX  Mean D a l l y U r i n e Volume Voided By Mink Housed I n M e t a b o l i s m Cages And Measured D u r i n g S t a r v a t i o n And D i g e s t i b i l i t y Starvation Vol. Mink No. PI  Day 1 2 3  V o l . Urine Mink No. PI PI  ml/day 42.0 49.0  P2 P2  51.5 84.0  P3  29.5  24.0 14.0 13.0  P4 P4  32.0 29.5  1 2 3 4 5  9.0 15.0 10.0 21.5 23.0  P5 P5 P5 P5 P5  40.5 50.5 29.0 57.5 53.0  1 2 3 4  10.0 8.5 12.0 11.0  -  1 2 3  14.0 14.5 19.0  P3  1 2 3  P4  P5  P2  Digestibility  Urine ml/day 22.0 12.5 12.0  Trials  

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