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The effect of vitamin A deficiency on some postmortem parameters of avian muscle Sundeen, Garfield Byron 1978

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THE EFFECT OF VITAMIN A DEFICIENCY ON SOME POSTMORTEM PARAMETERS OF AVIAN MUSCLE BY GARFIELD BYRON SUNDEEN B.Sc. ( A g r . ) , U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1973 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE i n THE FACULTY OF GRADUATE STUDIES Department o f Food S c i e n c e We a c c e p t t h i s t h e s i s as c o n f o r m i n g t o t h e r e q u i r e d s t a n d a r d THE UNIVERSITY OF BRITISH COLUMBIA November, 1977 f c ) G a r f i e l d Byron Sundeen, 1977 In presenting this thesis in p a r t i a l f ulfilment of the requirements for an advanced degree at the University of B r i t i s h Columbia, I agree that the Library shall make i t fr e e l y available for reference and study. I further agree that permission for extensive copying of this thesis for scholarly purposes may be granted by the Head of my Department or by his representatives. It is understood that copying or publication of this thesis f o r f i n a n c i a l gain shall not be allowed without my writ ten pe rm i ss i on . Department of FOOD SCIENCE The University of B r i t i s h Columbia 2075 Wesbrook Place Vancouver, Canada V6T 1W5 Date December 29,1977 i ABSTRACT The e f f e c t of the d i e t a r y s t a t u s of vitamin A on carbohydrate metab-o l i s m , postmortem isometric tension development and shear r e s i s t a n c e of Pectoral i s ma.jor muscle was st u d i e d . Depletion s t u d i e s , conducted over a f i v e week pe r i o d , i n d i c a t e d a d e f i n i t e influence of vitamin A d e f i c i e n c y on muscle carbohydrate metabolism. M i l d hypovitaminosis A induced an increase in glycogen d e p o s i t i o n whereas a severe d e f i c i e n c y led to a reduction of these elevated s t o r e s . Vitamin A def i c i e n c y did not a f f e c t the abi I i t y of F\_ ma.jor s t r i p s to develop isometric tension postmortem. P. ma.jor s t r i p s sampled from d e f i c i e n t cockerels g e n e r a l l y required longer to reach maximum tension and, in the l a t e r stages, developed s i g n i f i c a n t l y greater maximum tension than those of c o n t r o l s . The extended times t o maximum tension r e f l e c t e d an increased muscle glycogen content. A s i g n i f i c a n t increase in shear value s i m i l a r l y corresponded t o the increased m y o f i b r i l l a r c o n t r a c t i o n noted in the l a t e r d e f i c i e n c y stages. Cockerels which had p r e v i o u s l y received a completely vitamin A d e f i c i e n t r a t i o n f o r f i v e weeks were u t i l i z e d f o r the two week r e p l e t i o n study. Though there was a d i s t i n c t delay in response to the feeding of a vitamin A adequate r a t i o n , the muscle glycogen content, isometric tension parameters and shear values of re p l e t e d b i r d s were s i m i l a r t o those of c o n t r o l s w i t h i n the two week per i o d . TABLE OF CONTENTS Page ABSTRACT i LIST OF TABLES v ACKNOWLEDGEMENTS '.-vll INTRODUCTI ON 1 LITERATURE REVIEW 2 The e f f e c t of v i t amin A on carbohydrate metabolism 2 a) V i tamin A and l i v e r glycogen 2 b) V i tamin A and t i s s u e glycogen 4 R igor mor t i s , metabolism and i somet r i c tens ion 4 Tenderness and c o n t r a c t i o n s t a te 5 MATERIALS AND METHODS 7 P o u l t r y source 7 D ie t fo rmu la t ion and experimental design 7 S laughter procedure 10 I sometr ic tens ion measurement 10 Tenderness e va l ua t i on s 11 Sample p repara t ion 11 1) Ti ssue 1 1 2) L i v e r . 12 Chemical t e s t s , 12 1) Blood glucose and P. major pH 12 2) Metabo l i te a na l y s i s 13 3) L i v e r v i t amin A content 13 S t a t i s t i c a l a n a l y s i s 13 EXPERIMENT 1 Body weight I sometr ic tens ion and thaw r i g o r Blood g lucose, P. major pH .and ATP L i v e r EXPERIMENT 2 Mor ta I i t y rate Body weight Feed e f f i c i e n c y L i v e r weight and moisture content I sometr ic tens ion parameters a) Time to maximum tens ion b) Maximum i somet r i c tens ion P. major metabol i t e I'evels a) ATP b) Glycogen Shear values L i v e r glycogen and v i tamin A EXPERIMENT 3 M o r t a l i t y ra te Body weight Feed e f f i c i e n c y L i v e r weight and moisture content I sometr ic ten s i on parameters a) Time to maximum tens ion b) Maximum tens ion i v Page P. major metabolite l e v e l s 38 a) ATP 38 b) Glycogen 38 Shear value 38 L i v e r glycogen and vitamin A ' 41 DISCUSSION 44 SUMMARY AND CONCLUSIONS 53 LITERATURE CITED 54 V LIST OF TABLES Table Page I Wheat-soybean o i l meal basal d i e t 8 II Sucrose-casein basal d i e t 9 III The e f f e c t of d i e t a r y vitamin A on body weight. (Experiment 1) 15 IV Means and standard e r r o r s of time and tension development post-mortem and during thaw r i g o r f o r s t r i p s of Cornish White Rock P. major muscle run in phosphate b u f f e r . (Experiment 1) 16 V Means and standard e r r o r s of blood glucose and P. major i n i t i a l pH and ATP l e v e l . (Experiment 1) 17 VI Means and standard e r r o r s of l i v e r weight, moisture and glycogen content. (Experiment 1) 18 VII Means and standard e r r o r s of body weight. (Experiment 2) 20 VIII The e f f e c t of vitamin A on feed e f f i c i e n c y 21 IX Means and standard e r r o r s of l i v e r weight and moisture content 22 X Means and standard errors of time and tension development post-mortem f o r s t r i p s of White Leghorn cockerel P. major muscle run in phosphate b u f f e r 24 XI Means and standard e r r o r of P. major, ATP and glyqogen l e v e l s 26 XII • Means and standard e r r o r s of shear values f o r White Leghorn cockerel P. major 28 XIII C o r r e l a t i o n matrix f o r parameters studied in Experiment 2, control b i r d s 29 XIV C o r r e l a t i o n matrix f o r parameters studied in Experiment 2, treatment b i r d s 29 XV The e f f e c t of vitamin A d e f i c i e n c y on l i v e r glycogen and vitamin A content 31 XVI Means and standard e r r o r s of body weight. (Experiment 3) 33 XVII The e f f e c t of vitamin A on feed e f f i c i e n c y . (Experiment 3) 34 v i Table Page XVIII Means and standard e r r o r s of l i v e r weight and moisture content. (Experiment 3) 35 XIX Means and standard e r r o r s of time and tension development post-mortem f o r . s t r i p s of White Leghorn cockerel P. major muscle run in phosphate b u f f e r 37 XX Means and standard e r r o r s of P. major, ATP and glycogen l e v e l s 39 XXL Means and standard e r r o r s of shear values f o r White Leghorn cockerel P. major 40 XXII C o r r e l a t i o n matrix f o r parameters studied in Experiment 3, treatment b i r d s 41 XXIII The e f f e c t of vitamin A on l i v e r glycogen on vitamin A 43 ACKNOWLEDGEMENTS The a u t h o r would l i k e t o e x p r e s s h i s s i n c e r e a p p r e c i a t i o n t o h i s a d v i s o r , Dr. J . F. R i c h a r d s , P r o f e s s o r , Department o f Food S c i e n c e f o r h i s gui d a n c e and encouragement d u r i n g t h e c o u r s e o f t h i s s t u d y . He i s a l s o g r a t e f u l f o r t h e a d v i c e and c o n t i n u e d i n t e r e s t o f t h e members o f h i s g r a d u a t e committee: Dr. D. B. Bragg, Department o f P o u l t r y S c i e n c e Dr. J . V a n d e r s t o e p , Department o f Food S c i e n c e and e x t e n d s a s p e c i a l note o f t h a n k s t o Dr. Bragg f o r h i s a s s i s t a n c e i n t h e f o r m u l a t i o n and management of t h e d i e t s . The a u t h o r w i s h e s t o thank Mr. Mel Hudson and t h e s t a f f o f t h e p o u l t r y farm f o r t h e i r a s s i s t a n c e i n t h i s s t u d y . He i s a l s o g r a t e f u l t o Ms. E l l e n Holbek and M a r g a r e t Morrow f o r t e c h n i c a l a s s i s t a n c e and t o M i s s Lynne Robinson f o r computer a s s i s t a n c e . I would a l s o l i k e t o e x p r e s s my g r a t i t u d e t o my f r i e n d s f o r t h e i r p a t i e n c e and u n d e r s t a n d i n g . 1 INTRODUCTION The u l t i m a t e consumer a c c e p t a b i l i t y of muscle systems as food i s influenced by the t e x t u r a l c h a r a c t e r i s t i c of tenderness. In t u r n , t h i s sensory q u a l i t y has been resolved i n t o two s t r u c t u r a l components: a 'background tough-ness' a t t r i b u t a b l e to connective t i s s u e and other stromal p r o t e i n s and an 'actomyosin toughness' from the c o n t r a c t i l e apparatus. The extent of the l a t t e r ' s c o n t r i b u t i o n w i l l depend on the events of r i g o r mortis - "the s t i f f e n i n g and loss of e x t e n s i b i l i t y in postmortem muscle" (BendalI 1973). This s t i f f e n i n g and loss of e x t e n s i b i l i t y in postmortem s k e l e t a l muscle i s an obvious change associated with a complexity of chemical events. One of these i s the disappearance of glycogen v i a anaerobic g l y c o l y s i s , and both the rate and extent of the concomitant pH d e c l i n e have been r e l a t e d t o muscle tenderness. A shortening or c o n t r a c t i o n i s another p h y s i c a l event t h a t has been demonstrated in p r e r i g o r , postmortem muscle and s i m i l a r l y r e f l e c t s the chemical events which occur. This shortening can be e a s i l y monitored q u a n t i t a t i v e l y by isometric tension measurement, a technique which i s becoming an i n c r e a s i n g l y important a n a l y t i c a l t o o l f o r measuring the ante and postmortem f a c t o r s of tenderness. The d i e t a r y s t a tus of vitamin A i s one n u t r i t i o n a l f a c t o r which exerts an e f f e c t on carbohydrate metabolism and t h i s study was conducted t o examine t h i s e f f e c t in r e l a t i o n t o postmortem isometric t e n s i o n development and u l t i m a t e muscle tenderness. 2 LITERATURE REVIEW The e f f e c t of vitamin A on carbohydrate metabolism Since the simultaneous discovery of vitamin A by McCollum and Davis (1913) and Osborne and Mendel (1913), numerous i n v e s t i g a t o r s have demon-s t r a t e d t h a t a l l vertebrates require t h i s f a t - s o l u b l e compound. The most important natural source i s f i s h l i v e r o i l s b u t i the i n i t i a l source i s p l a n t m a t e r i a l s and the vitamin A a c t i v i t y of the l a t t e r i s due t o t h e i r content of provitamin A carotenoids. R e t i n p l , r e t i n a l , r e t i n o i c a c i d and some of t h e i r stereoisomers possess vitamin A a c t i v i t y f o r the chicken and the various provitamins A are converted into these compounds in the i n t e s t i n a l mucosa. The e s s e n t i a l r o l e of vitamin A stereoisomers in the process of v i s i o n i s well known, but several other b o d i l y f u n c t i o n s are a l s o a f f e c t e d by the d i e t a r y s t a t u s of t h i s v i t a m i n . These fu n c t i o n s include growth, the prevention of severe a t a x i a , maintenance of the normal i n t e g r i t y of mucous membrane, reproduction, the proper growth of c a r t i l a g e matrix and the maintenance of normal cerebrospinal f l u i d pressure (Scott e t a I., 1969). Several workers have a l s o i n v e s t i g a t e d the r o l e of vitamin A in carbohydrate metabolism, a) Vitamin A and l i v e r glycogen In vitamin A d e f i c i e n t r a t s , Johnson and Wolf (1960) found a lowered i n c o r p o r a t i o n of l a b e l l e d acetate, l a c t a t e and g l y c e r o l i n t o l i v e r glycogen and e s s e n t i a l l y no glycogen d e p o s i t i o n in the l i v e r . Vitamin A d e p r i v a t i o n did not a f f e c t l a b e l l e d glucose i n c o r p o r a t i o n but subsequent in v i t r o stud ies c o n t r a d i c t e d these r e s u l t s . These authors suggested that the e f f e c t of a v i t a m i n o s i s A on glycogen metabolism from acetate r e f l e c t e d a chemical adrenalectomy with respect t o g l u c o c o r t i c o i d b i o s y n t h e s i s . 3 Stoewsand and Scott (1964) studied the e f f e c t of a d i e t a r y s t r e s s on vitamin A metabolism in c h i c k s . They reported t h a t high p r o t e i n d i e t s produced a s t r e s s s i t u a t i o n , evidenced by adrenal hypertrophy and h y p e r a c t i v i t y . Though d a i l y i n j e c t i o n s of c o r t i c o s t e r o n e a l l e v i a t e d these symptoms, they g e n e r a l l y decreased l i v e r vitamin A stores and concomitantly increased plasma vitamin A. L i v e r glycogen formation a f t e r a 1 day f a s t did not appear t o be impaired by vitamin A d e f i c i e n c y upon four hours of refeeding. However, when t h i s refeeding period was extended to 24 hours, the amount of l i v e r glycogen formed/gm t o t a l feed consumed was s i g n i f i c a n t l y decreased. The decrease in l i v e r glycogen during vitamin A d e f i c i e n c y observed by Perek and Kendler (1969), was not s u b s t a n t i a t e d by Nockels and P h i l l i p s (1971b). The l a t t e r authors found t h a t the amountiof l i v e r glycogen/gm dry matter was greater in 4 week o l d vitamin A d e f i c i e n t b i r d s than in those r e c e i v i n g the c o n t r o l d i e t . For those b i r d s maintained on the basal d i e t supplemented with 600 USP u n i t s vitamin A palmitate/kg r a t i o n t h i s d i f f e r e n c e was s i g n i f i c a n t , whereas f o r those which received a lower leve l (300 USP u n i t s / k g ) , the d i f f e r e n c e was n o n s i g n i f i c a n t when compared t o c o n t r o l s . Apparently c o n t r a d i c t o r y r e s u l t s were l a t e r reported by these same authors (Nockels et aj_., 1973). In t h i s study a v i t a m i n o s i s A i n i t i a l l y increased plasma c o r t i c o s t e r o n e s i g n i f i c a n t l y . This was followed by a decrease in plasma c o r t i c o s t e r o n e and percent l i v e r glycogen as the d e f i c i e n c y progressed. Despite a s c o r b i c a c i d supplementation, no improvement was noted in c o r t i c o s t e r o n e level or in the percent l i v e r glycogen of 7 week o l d b i r d s . Two recent s t u d i e s with r a t s question the research emphasis on a d r e n o c o r t i c a l a c t i o n in vitamin A d e f i c i e n c y . Janson and H a r i l l (1974) reported t h a t a vitamin A d e f i c i e n c y led to a decrease in l i v e r glycogen 4 concentration i r r e s p e c t i v e of the d i e t a r y N source. The decrease was noted without a s i g n i f i c a n t a l t e r a t i o n in serum c o r t i c o s t e r o n e l e v e l s . Dileepan et aj_. (1974) found t h a t /.avitaminosis A did not influen c e hepatic glycogen l e v e l s or adenyl c y c l a s e a c t i v i t y but diminished hepatic phosphodiesterase a c t i v i t y . They suggested t h a t the a l t e r a t i o n s of glycogen metabolism are p a r t l y due to changes in hepatic c y c l i c adenosine monophosphate l e v e l s , b) Vitamin A and t i s s u e glycogen Although the formation of glycogen occurs in p r a c t i c a l l y every t i s s u e of the body and p r i m a r i l y in l i v e r and muscle, only the report of one study which s p e c i f i c a l l y i n v e s t i g a t e d the e f f e c t of vitamin A on t i s s u e glycogen could be found. Nockels and P h i l l i p s (1971a) examined the progress of a v i t a m i n o s i s A in chickens f o r 4, 8, 16, and 24 weeks. They reported t h a t s t a t i s t i c a l l y there were no d i f f e r e n c e s in muscle glycogen content between vitamin A d e f i c i e n t b i r d s and c o n t r o l s ; however, there was a d e f i n i t e trend i n d i c a t i n g increased muscle glycogen with i n c r e a s i n g vitamin A d e f i c i e n c y in 8 and 16 week o l d chickens. A s i m i l a r pattern was observed f o r muscle ATP l e v e l s . Rigor mortis, metabolism and isometric tension Bendall (1973) has defined r i g o r mortis as the s t i f f e n i n g and loss of e x t e n s i b i l i t y in postmortem muscle. I t i s an obvious postmortem change associated with a complexity of chemical events t h a t r e a l i z e s the disappearance of N phosphorylcreatine, ATP and glycogen and the appearance of i n o s i n i c a c i d , ammonia and l a c t i c a c i d (deFremery, 1966). The accumulation of l a c t i c a c i d from anaerobic g l y c o l y s i s causes the pH of the muscle to f a l l and t h i s i s . a . ;••:.! c e n t r a l f a c t o r underlying the phys i c a l changes of r i g o r mortis (Bate-Smith, 1948). Both the rate and extent of postmortem pH f a l l have been r e l a t e d t o ult i m a t e muscle tenderness (Newbold and H a r r i s , 1972). 5 In a d d i t i o n t o l o s i n g e x t e n s i b i l i t y , unrestrained muscle shortens during r i g o r development and the extent of t h i s c o n t r a c t i o n i s dependent on the presence of ATP and on temperature. The mechanism of t h i s postmortem shortening i s believed t o be the same as muscular c o n t r a c t i o n in v i v o , the presently-known d e t a i l s of which can be found in recent reviews (Murray and Weber, 1974; Cohen, 1975; Mannherz and Goody, 1976). This occurance has led t o the development of a new technique t o f o l l o w the time-course of r i g o r : i s o m e t r i c tension development. Busch e t aj_. (1967) and Jungk e t §_[_• (1967) f i r s t reported the pattern of postmortem isometric t e n s i o n development and d e c l i n e in bovine and r a b b i t muscle. This pattern has been f u r t h e r demonstrated t o be a widespread phenomenon occuring in bovine (Busch e t a]_., 1967, 1972; Jungk e t aj_., 1974), chicken (Khan, 1974; Wood and Richards, 1974; Khan and Kim, 1975), porcine (Schmidt e t a j _ . , 1970a, b; Busch et aj_., 1972), r a b b i t (Busch e t aj_., 1972; Jungk e t aj_., 1974), and turkey muscle (Jungk and Marion, 1970; Marion, 1971; Vanderstoep and Richards, 1974). The most f r e q u e n t l y reported parameters of isometric t e n s i o n are the time t o maximum tension and the maximum te n s i o n developed, and most of the indi c a t e d s t u d i e s i n v e s t i g a t e d the response t o various treatments as well as the r e l a t i o n s h i p t o metabolite l e v e l s . Tenderness and c o n t r a c t i o n s t a t e In t h e i r reviews on the biochemical and b i o p h y s i c a l b a sis of tenderness in muscle foods, both Cassens (1977) and Marsh (1977) emphasized t h a t the toughness of meat i s the r e s u l t of two components: a 'background toughness' a t t r i b u t a b l e t o connective t i s s u e and other stromal p r o t e i n s and an 'actomyosin toughness' from the c o n t r a c t i l e apparatus. The e a r l y s t u d i e s which e s t a b l i s h e d the asso-c i a t i o n between c o n t r a c t i o n and tenderness used sarcomere length as the index 6 of c o n t r a c t i o n s t a t e (Herring et_ aj_., 1965; Marsh and Leet, 1966; Howard and Judge, 1968). Several recent s t u d i e s have attempted t o r e l a t e i s o m e t r i c t e n s i o n parameters and shear r e s i s t a n c e . Busch et a]_. (1967) reported t h a t isometric tension parameters and shear were somewhat r e l a t e d a t 2°C in beef semi tendinosus but not at 16° or 37°C. They suggested t h a t at higher temperatures other f a c t o r s besides shortening may be more important. In an experiment conducted by Wood (1973) t o i n v e s t i g a t e the e f f e c t of epinephrine i n j e c t i o n s on meat tenderness, s i g n i f i c a n t p o s i t i v e c o r r e l a t i o n s were found f o r shear values with both time and t e n s i o n . Khan (1974) reported t h a t the u l t i m a t e shear for c e of p o u l t r y breast meat cooked at 20 hours postmortem.appeared t o be d i r e c t l y p r o p o r t i o n a l t o the maximum tension developed. A l a t e r study by Khan and Kim (1975) found t h a t treatments which acce l e r a t e d g l y c o l y s i s and the onset of r i g o r mortis, measured i s o m e t r i c a l l y , induced toughness in chicken muscle. The lack of information on the e f f e c t o o f vitamin A d e f i c i e n c y on muscle glycogen, the recognized i n t e r r e l a t i o n s h i p between glycogen a v a i l a b i l i t y and muscle c o n t r a c t i o n , and the s e n s i t i v i t y of the isometric t e n s i o n measurement technique t o changes in postmortem shortening provide the basis f o r the research presented in t h i s t h e s i s . 7 MATERIALS AND METHODS Po u l t r y source Day-old b i r d s were obtained from a commercial hatchery and t r a n s -ported to the U.B.C. p o u l t r y farm. In the pr e l i m i n a r y study, designated Experiment 1, Cornish White Rock b i r d s of both sexes were used. Subsequent s t u d i e s u t i l i z e d White Leghorn c o c k e r e l s . Diet formulation and experimental design The basal wheat-soybean o i l meal d i e t of Experiment 1 i s shown in Table 1 and i s s i m i l a r to th a t of Nockels and Kienholz (1967). The four l e v e l s of vitamin A supplementation u t i l i z e d were 375, 750, 1125, and 5000 lU/kg r a t i o n , with the highest level s e r v i n g as the co n t r o l d i e t . F i f t e e n day-old b i r d s were randomly a l l o t t e d t o each d i e t and were reared in e l e c t r i c a l l y heated battery brooders u n t i I 5 weeks o l d , when they were placed in growing b a t t e r i e s . They received feed and water ad Iibiturn and were i n d i v i d u a l l y weighed at weekly i n t e r v a l s . The p u r i f i e d casein-sucrose d i e t shown in Table 2 was the basal d i e t f o r both Experiments 2 and 3, and was formulated on a weekly b a s i s . In Experiment 2, one hundred f i f t y day-old c h i c k s were placed in e i g h t e l e c -t r i c a l l y heated battery brooders; in Experiment 3 one hundred b i r d s were used. In both s t u d i e s , the ch i c k s were maintained on the basal d i e t supplemented with 5000IU vitamin A/kg r a t i o n u n t i l 5 weeks o l d , at which time they were randomly a l l o t t e d to e i t h e r a vitamin A - d e f i c i e n t or vitamin A-adequate (5000t1U/kg) r a t i o n and placed in growing b a t t e r i e s . In Experiment 3 those b i r d s success-f u l ly completing 5 weeks of vitamin A d e f i c i e n c y were reassigned t o the con t r o l d i e t . In both s t u d i e s feed and water were a v a i l a b l e ad Iibiturn and the b i r d s were i n d i v i d u a l l y weighed at weekly i n t e r v a l s . B i r d s in Experiments 2 and 3 received an i n t r a o c u l a r i n n o c u l a t i o n against Newcastle disease a t 7 and 5 weeks of age r e s p e c t i v e l y . 8 Table I: Wheat-soybean o i l meal basal d i e t Percent wheat < 1 356P) 65.8 soybean o i l meal, solvent process^C48;5#P) 24.2 di c a l c i u m phosphate 2.7 Iimestone 0.8 s a l t , iodized 0.5 DL methionine 0.22 animal f a t 5.0 Vitamins added/kg r a t i o n vitamin 990 IU ^tocopherol acetate 12 IU c h o l i n e 1980 mg r i b o f l a v i n 2.54 mg vitamin K 1.16 mg n i a c i n 27 mg (Ca) pantothenic a c i d 10 mg vitamin B]2 11.10 ug Minerals added/kg r a t i o n MnSO "H„0 80 mg ZnCO^ 31 mg CuS0,-'5Ho'0 4 mg 4 2 9 Table I I : Sucrose-casein basal d i e t /100Hb I ration.: sucrose case? n g e l a t i n r e f i n e d s a f f l o w e r o i l a Ipha ceI I L a r g i n i n e hydrochloride g I yc i ne DL methionine ("SaffIo") 2 57.54 20.00 5.00 4.00 3.00 1 .50 1 .00 0.40 lb Vitamin premix n i c o t i n i c a c i d 2.2680 gm thiamine hydrochloride 0.6804 r i b o f l a v i n 0.6804 f o l i c a c i d 0.2722 pyridoxine 0.2722 b i ot i n 0.0272 c h o l i n e c h l o r i d e 90.7185 santoqu i n 4.5359 d Ca pantothenate 0.9072 menadione Na b i s u l f i t e 0.0680 vitamin vitamin 6.8038 1.0206 vitamin E 4.5318 Mi neraI Ingred ients d i c a l Iimestone KH 2P0 4 NaHCO, MgSO FeSO^ MnSO^ ZnCO, Cuso; KI0, 7H 0 H 20 5H 20 Na JioO.- 2H 0 Na^SeO^ CaCI 2 /100 lb r a t i o n 1.80 lb 1.90 1 .40 399.16 136.08 22.68 15.876 6.8039 1 .3608 0.4536 0.3765 0.0907 0.0771 gm 1 adapted from Scott e± aj_. (1969) 2 L .argirvirie hydrochloride supplementation ceasecl a f t e r 10 weeks 10 Slaughter procedure The sampling of the b i r d s in Experiment 1 began when they were e i g h t weeks o l d and continued u n t i l the supply was exhausted. Four b i r d s , one from each treatment, were k i l l e d each day. B i r d s were placed in a metal funnel and were exsanguinated by an outside neck cut and allowed t o bleed f r e e l y . In a d d i t i o n to t h a t provided by the f u n n e l , r e s t r i c t i o n of wing and leg movement during slaughter was manually aided. In Experiment 2, e i g h t b i r d s from each treatment were s e l e c t e d a t 6, 7, 8, 9, and 10 weeks of age, corresponding t o one through f i v e weeks of treatment, and were k i l l e d by c e r v i c a l d i s l o c a t i o n . Four b i r d s , two c o c k e r e l s from each treatment, were k i l l e d each day f o r fo u r days. The wings and legs were manually r e s t r a i n e d during s l a u g h t e r . An i d e n t i c a l s e l e c t i o n and slaughter procedure was u t i l i z e d in Experiment 3, beginning at 9 weeks and c o n t i n u i n g u n t i l the b i r d s were 12 weeks of age. This period corresponded t o the f o u r t h and f i f t h week of d e f i c i e n c y and the f i r s t and second week of r e p l e t i o n f o r t h i s study. Isometric tension measurement The development and d e c l i n e of iso m e t r i c t e n s i o n was monitored with an E + M 6-channel physiograph* f i t t e d with i s o m e t r i c transducers. P. major muscle s t r i p s f o r te n s i o n measurement were prepared according t o the method of Wood and Richards (1974) with one m o d i f i c a t i o n : the muscle s t r i p s were cut to 4 cm in length. Three s t r i p s f o r each b i r d were excised and allowed t o develop i s o m e t r i c tension in phosphate b u f f e r pH 7.2, i o n i c strength 0.15 (Gomori 1955). The maximum time lapse from exsanguination to the attachment of s t r i p s was 20 minutes. *Narco-Bio-Systems Inc., Houston, Texas 11 Thaw r i g o r development was measured only f o r those b i r d s in Experiment 1. Three P. major muscle s t r i p s from each b i r d , excised and prepared in the manner p r e v i o u s l y described, were i n d i v i d u a l l y wrapped in Saran Wrap and placed in a -37°C b l a s t f r e e z e r . Twenty-four hours postmortem these s t r i p s were removed, attached t o the t e n s i o n measurement system and allowed t o thaw. To prevent severe surface dehydration about 4 cm of phosphate b u f f e r was placed in the bottom of the chamber and the top of the chamber was covered with aluminum f o i l a l l o w i n g a small space f o r the attachment of the s t r i p t o the transducer. Tenderness ev a l u a t i o n s The muscle samples used f o r isometric t e n s i o n measurements and metabolite analyses were excised from the same P. major of each b i r d . The remaining, i n t a c t P. major was covered with Saran Wrap, packed in drained crushed ice and aged f o r 24 hours at 2°C. Tenderness measurements were performed in a manner s i m i l a r t o t h a t reported by deFremery and Pool (1960). The breast muscle was e x c i s e d , placed between two aluminum p l a t e s held apart at a constant t h i c k n e s s , immersed In b o i l i n g water f o r 10 minutes, then cooled i n c o l d tap water f o r 5 minutes. S t r i p s of p a r a l l e l f i b e r s , 1.0 cm wide, were prepared and each s t r i p ' s recorded th i c k n e s s represents the average of measurements along i t s length. Shear was measured on an Instrov Universal T e s t i n g Instrument (Model 1122) f i t t e d with an Allo-Kramer s i n g l e blade shear attachment. A l l shears were performed with a crosshead speed of 100 mm/min and a f u l l s c a l e d e f l e c t i o n of 10 kg. A minimum of 6 shears per b i r d was obtained. Sample preparation 1) Tissue Muscle samples f o r chemical t e s t s were taken a f t e r the P. major s t r i p s had been excised f o r isometric tension measurement. The samples were 12 frozen in l i q u i d nitrogen (LN^) and stored in aluminum f o i l envelopes at -37°C and subsequently powdered according t o the method of Borchert and Briskey (1965) as modified by Vanderstoep and Richards (1974). The frozen samples were removed and p u l v e r i z e d in a macro model V i r t i s homogenizer f o r 1.5 min. at 11000 rpm. Care was taken t o ensure the sample remained frozen at a l l times. The powdered sample was replaced in aluminum f o i l envelopes and stored at -37°C u n t i l e x t r a c t e d . 2) L i v e r L i v e r s were removed, b l o t t e d on paper towels and weighed. They were immediately frozen in Lls^, placed in aluminum f o i l envelopes and stored at -37°C u n t i l f r e e z e - d r i e d . Dry l i v e r s were weighed and ground t o a powder with mortar and p e s t l e . The l i v e r powder was stored in f o i l envelopes in a dess i c a t o r . Chemical t e s t s 1) Blood qlucose_arid P. major pH Blood glucose determinations were done f o r Experiment 1 only. Blood was c o l l e c t e d at the time of exsanguination in a t e s t tube c o n t a i n i n g 20 mg potassium o x a l a t e and 25 mg sodium f l o r i d e . Glucose was measured in whole, deproteinated blood using the g l u c o s t a t * method (Washko 1969). Absorbance was measured with a Beckman DB spectrophotometer at 420 nm. The i n i t i a l pH of the muscle sample In Experiment 1 was determined by modifying the method of Cassens and Newbold (1967). 1 - 2 g of muscle t i s s u e was homogenized with 20 ml n e u t r a l i z e d 0.005M sodium iodoacetate in a Waring L-1.;•;•[, rblender f o r 5 min. pH was determined with a Fisher Accumet, Model 230 pH Meter. *Worthington Biochemical Corp., Freehold, N. J . 13 2) Metabolite a n a l y s i s Tissue ATP determinations were conducted f o l l o w i n g the method of Lamprecht and Trautschold (1963) as modified by Wood (1973). L i v e r and t i s s u e glycogen was ext r a c t e d from powdered samples by an enzymatic method u t i l i z i n g amylo<*1, A-<, 6 glucosidase (Dalrymple and Hamm 1973) and determined as D-glucose by the method of P f l e i d e r e r (1963). A l l absorbance measurements were made with an Unicam SP800 recording s pect rop hotomete r. 3) L i v e r vitamin A content The a n a l y s i s f o r vitamin A was performed on pooled l i v e r samples, each b i r d of the same treatment c o n t r i b u t i n g 2 g of powder. T r i p l i c a t e determinations were obtained according t o the method of Dugan et aj_. (1964), a c o l o r i m e t r i c determination with t r i f l u o r o a c e t i c a c i d . Absorbance was measured at 616 nm with a Beckman DB spectrophotometer. S t a t i s t i c a l a n a l y s i s D i f f e r e n c e s between treatment means were analyzed f o r s t a t i s t i c a l s i g n i f i c a n c e by the. t - t e s t according t o the method of Steel and Torn ie (1960). ( 14 RESULTS Experiment 1  Body weight The e f f e c t of d i e t a r y vitamin A on body weight gains i s presented in Table I I I . Those c h i c k s r e c e i v i n g the lowest leve l of vitamin A supplemen-t a t i o n (375 lU/kg) had s i g n i f i c a n t l y higher (p<0.05) body weights a t 1 week of age than those on the c o n t r o l d i e t . T h e i r mean value remained numerically greater f o r another two weeks, a f t e r which the trend was reversed. The body weights of the ch i c k s r e c e i v i n g the three lowest treatment l e v e l s were lower than c o n t r o l s at 6, 7, and 8 weeks of age; only those c h i c k s on the lowest .level (375 lU/kg) had s i g n i f i c a n t l y l i g h t e r (p<0.05) body weights at 8 weeks of age. Isometric t ension and thaw r i g o r The data f o r isometric t e nsion and thaw r i g o r development are shown in Table IV. No s i g n i f i c a n t d i f f e r e n c e s o r d e f i n i t e trends in e i t h e r the time to maximum tension or the maximum tension developed were evident. Blood glucose, P. major pH and. ATP The data f o r these three parameters are presented in Table V. Blood glucose l e v e l s were s l i g h t l y lower and white muscle i n i t i a l pH and ATP values were s l i g h t l y higher f o r those c h i c k s r e c e i v i n g d e f i c i e n t d i e t s though no s t a t i s t i c a l d i f f e r e n c e s were noted.= Table I I I : The effect of dietary vitamin A on body weight (Experiment 1) Body Weight (g) Age in Weeks Dietary Vitamin A Day-old ( lU/kg diet) 5 i 7; 375 750 1125 5000(C)-42±0.7a 106±2.3b 232±5.4a 40±0.9a 100±2.8a 213±4.6a 41±0.8a 92±3.0a 200±6.0b 39±1.1a 96±2.8a 221±6.1a 428± 8.1a 617± 8.2a 821±12.4a 1127±21.2a 1383±28.2a 1627±38.4b 407±11.0a 642±19.8a 907±28.0a 1147±33'.4a 1375±47.5a 1738±55.0a 387±10.0a 597±13.2a 838±19.4a 1157±34.0a 1435±44.9a 1789±64.3a 412± 7.8a 626±14.9a 855±20.6a 1184±35.0a 1466±46.5a 1801±68.8a 1 mean and standard error 2 means in same column followed by si m i l a r letters do not d i f f e r s i g n i f i c a n t l y (p<0.05) 3 C = control Table IV: Means and standard e r r o r s of time and tension development postmortem and during thaw r i g o r f o r s t r i p s of Cornish White Rock P. major muscle run in phosphate b u f f e r . (Experiment 1) Isometric Tension Parameters Thaw Rigor Dietary Vitamin A Time t o Maximum Maximum Tension Time to Maximum ;iMax!mum-Tensi on 2 2 (lU/kg d i e t ) Tension (hours) Developed (gm/cm ) Tension (minutes) (gm/cm ) 375 4.93 + 0.49a 63.1 + 4.9a 8.8 + 0.6a 196.0 + 12.9a 750 5.02 + 0.48a 54.8 + 4.0a 7.7 + 0.8a 194.6 + 5.2a 1 125 5.20 + 0.60a 59.5 + 3.4a 9.6 + 0.9a 198.7 + 7.4a 5000 (C) 4.79 + 0.72a 62.6 + 5.0a 8.4 + 0.5a 214.0 + 18.0a 1 means in same column followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 17 Table V: Means and standard e r r o r s of blood glucose and P. major i n i t i a l pH and ATP l e v e l . (Experiment 1) Dietary Vitamin A Blood Glucose I n i t i a l ATP (Ill / k g d i e t ) Level (mg#) pH (/imoles/gm) 375 170 ± 6.9a 1 6.24 ± 0.05a 6.17 ± 0.51a 750 174 ± 6.6a 6.20 ± 0.06a 6.28 ± 0.48a 1125 170 ± 7.1a 6.20 ± 0.06a 6.74 ± 0.49a 5000 (C) 181 ± 7.6a 6.12 ± 0.07a 5.87 ± 0.62a 1 means in same column followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) Li ver L i :r On a weight basis the c h i c k s r e c e i v i n g 375 and 750 IU vitamin A/kg had s i g n i f i c a n t l y lower l i v e r weights (p<0.10) than the c o n t r o l s (TabIe V I ) . Those r e c e i v i n g 750 lU/kg maintained t h i s s i g n i f i c a n t d e f i c i t when l i v e r weights were expressed as a body weight percentage. There did not appear t o be a s i g n i f i c a n t e f f e c t of vitamin A d e p r i v a t i o n on l i v e r moisture content f o r those c h i c k s maintained on the 375 and 750 lU/kg r a t i o n s . However, a s i g n i f i c a n t l y higher (p<0.10) l i v e r moisture content was e x h i b i t e d by those r e c e i v i n g a moderate level of vitamin A (1125 lU/kg). These b i r d s a l s o had a s l i g h t l y lower glycogen content but no s i g n i f i c a n t e f f e c t of vitamin A d e f i c i e n c y on l i v e r glycogen i s otherwise demonstrated. Table VI: Means and standard e r r o r s of l i v e r weight, moisture and glycogen content (Experiment 1) L i v e r Weight L i v e r moisture L i v e r glycogen Dietary Vitamin A gm % body weight {%) (jumoles glucose/gm dry wt.) (lU/kg d i e t )  375 44. .2 + 1 . 7b 1 2, .00 + 0.04a 68. ,7 + 0. 7a 310.2 + 28.3a 750 44, .7 + 1 . 8b 1, .87 + 0.04b 69. ,3 + 0. 6a 317.1 + 27.1a 1125 48. .8 + 2. 4a 2, .02 + 0.11a 69. .7 + 0. 6b 253.0 + 35.2a 5000 (C) 51, .4 + 2. 4a 2, .05 + 0.05a 68. ,4 + 0. 4a 305.0 + 21.5a 1 means in same column followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 19 Experiment 2  M o r t a l i t y rate An unusually high m o r t a l i t y r a t e of 27.4$ (42 out of 153 b i r d s ) was recorded f o r the f i r s t week of the experimental period and t h i s r a t e increased s l i g h t l y to 28.1$ in the subsequent four weeks p r i o r t o treatment a l l o c a t i o n . By the end of the f i v e weeks of treatment, corresponding t o 6 through 10 weeks of age, c o n t r o l b i r d s (5000 lU/kg) e x h i b i t e d a 7.3$ m o r t a l i t y rate whereas those r e c e i v i n g the a v i t a m i n o t i c A r a t i o n had 13$ m o r t a l i t y . As some c o n t r o l and a v i t a m i n o t i c A b i r d s showed p r e l i m i n a r y symptoms of Newcastle disease, each group received i n t r a o c u l a r v a c c i n a t i o n s at 7 weeks of age. No deaths were recorded in e i t h e r group f o r the f o l l o w i n g two weeks. Body weight Table VII presents the average body weights f o r the t o t a l number of b i r d s used from a treatment group, as well as the weekly and terminal body weights of those b i r d s sampled at each stage of the experiment. For the f i v e week treatment period no s i g n i f i c a n t d i f f e r e n c e s in body weight were observed. Feed e f f i c i e n c y Feed e f f i c i e n c y values f o r those b i r d s sampled a t each stage are prese in Table V I I I . In t h i s and subsequent t a b l e s , two data columns are shown under the vitamin A d e f i c i e n t heading. The f i r s t column represents the average values of the parameter f o r a l l the sampled b i r d s , while the values which appear in the second column are the means only f o r those sampled b i r d s which showed p o s i t i v e weight gains. Henceforth, these s h a l l be r e f e r r e d t o as d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s r e s p e c t i v e l y . Table V l l : Means and standard e r r o r s of body weight (Experiment 2) Duration of Treatment ( i n weeks) 1 Weekly Weight of B i r d s used Weekly Weight of Sampled B i r d s Terminal Weight of Sampled B i r d s Control Vitamin A D e f i c i e n t UContro 1 Vitamin A D e f i c i e n t ControI Vitamin A D e f i c i e n t 0 \ 1 2 3 4 5 337±;777a2 413±9'.8a 546±13.3a 684±21.8a 793±28.6a 916±37.0a 351 ± :6.4a 435± :8.4a 565±13.4a 736118.8a 817±25.4a 880±50.4a 394±24.4a 563±23.1a 668±51.3a 798±46.6a 916±37.0a 439±14.8a 546±32.1a 680±30.5a 812±29.9a 880±50.4a 427±27.9a 594±17.2a 680±50.8a 845±50.4a 966±48.1a 475±22.4a 580±29.2a 688±32.8a 833±32.7a 885±45.la 1 Week 0 corresponds t o 5 weeks of age 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.05) 21 Vitamin A d e f i c i e n c y did not s i g n i f i c a n t l y a f f e c t feed e f f i c i e n c y • though treatment b i r d s had numerically lower values than the c o n t r o l s a t each stage. Control and treatment b i r d s showed decreasing feed e f f i c i e n c y with in c r e a s i n g age and when the data were subjected t o regression a n a l y s i s s i g n i f -icant regression c o e f f i c i e n t s of r = -.895 (p<0.02), r = -.981 (p<0.001), and r = -.988 (p<0.001) were obtained f o r the c o n t r o l , d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s r e s p e c t i v e l y . Table V I M : The e f f e c t of vitamin A on feed e f f i c i e n c y Feed e f f i c i e n c y (gm/gm feed consumed) Vitamin A d e f i c i e n t Duration of Treatment ( i n weeks) Control D e f i c i e n t M i l d l y d e f i c i e n t 1 0.394 ± 0.02aA 0.418 ± 0.02aA^ 2 0.410 ± 0.02aA 0.404 ± 0.02aA 3 0.369 ± 0.03aA 0.356 ± 0.02aB 0.366 ± 0.02aB 4 0.357 ± 0.02aA 0.341 ± O.OlaB 0.354 ± 0.01aB 5 0.345 ± 0.02aA 0.320 ± O.OlaB 0.326 ± 0.02aB 1 mean and standard e r r o r 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 3 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 1 (p-'O.IO) L i v e r weight and moisture content No s i g n i f i c a n t d i f f e r e n c e s in were r e a l i z e d u n t i l the f i f t h treatment in vitamin A showed s i g n i f i c a n t l y lower c o n t r o l s . (Table IX) l i v e r weight on a gm weight basis week when the c h i c k s which were d e f i c i e n t l i v e r weights (p<0.10) than the Table IX: Means and standard e r r o r s of l i v e r weight and moisture content Vitamin A d e f i c i e n t Duration of "Treatment ' Control D e f i c i e n t M i l d l y d e f i c i e n t ( i n weeks) L i v e r Weight (gm) 1 13.2 ± 0.9aA 14.0 + 0.7aAi, 2 16.1 ± 0.8aB 15.3 + 0.8aA 3 18.5 ± 1.4aB 17.1 + .1.6aB 16.6 + 1.7aA 4 19.9 i ±-1.8aB 18.8 + 0.6aB 17.6 + 0.4aB 5 26.5 ± 2.6aB 18.3 + 1.3bB 19.7 + 1.4bB L i v e r Weiqht (as % body weiqht) 1 3. 18 ± 0.3aA 2.96 + 0.1aA 2 2.73 ± 0.2aA 2.65 + 0.1aA 3 2.72 ± 0.1aA 2.50 + 0.2aA 2.33 + 0.2bB 4 2.37 ± 0.2aB 2.31 + 0.2aB 2.04 + 0.1aB 5 2.69 ± 0.2aA 2.11 + 0. IbB 2.21 + 0. IbB L i v e r moisture content (decimal) 1 2 3 4 5 0.709 ± 0.008aA 0.720 ± 0.004aA 0.714 ± 0.006aA 0.721 ± 0.004aA 0.695 ± 0.012aA 0.730 ± 0.004bA 0.713 ± 0.005aB 0.725 ± 0.004aA 0.699 ± 0.011aB 0.711 ± 0.007aB 0.725 ± 0.004aA 0.698 ± 0.004bB 0.707 ± 0.018aB 1 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 2 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 1 (p<0.10) 23 A d e f i n i t e trend of inc r e a s i n g l i v e r weight with i n c r e a s i n g age was noted f o r co n t r o l and treatment b i r d s and s i g n i f i c a n t regression c o e f f i c i e n t s of r = .965 (p<0.002), r = .962 (p<0.005) and r = .995 (p<0.001) were c a l c u l a t e d f o r the c o n t r o l , d e f i c i e n t and m-ildly d e f i c i e n t groups r e s p e c t i v e l y . When l i v e r weight i s expressed as percent body weight, d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s had s i g n i f i c a n t l y l i g h t e r l i v e r s than c o n t r o l s (p<0.10) at the f i f t h treatment week; a d d i t i o n a l l y , m i l d l y d e f i c i e n t b i r d s had s i g n i f -i c a n t l y l i g h t e r l i v e r s than c o n t r o l s (p<0.10) at the t h i r d treatment week. A d e f i n i t e trend can be seen with respect to age; in d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s l i v e r weight as percent body weight decreased with i n c r e a s i n g age. S i g n i f i c a n t regression c o e f f i c i e n t s of r = -.993 (p<0.001) and r = -.948 (p<0.005) were obtained f o r the d e f i c i e n t and m i l d l y d e f i c i e n t groups r e s p e c t i v e l y . No recognizable trend i s ind i c a t e d f o r the c o n t r o l group. Neither c o n t r o l nor treatment groups d i s p l a y a c o n s i s t e n t pattern with respect to l i v e r moisture; d e f i c i e n t b i r d s had a s i g n i f i c a n t l y higher l i v e r (p<0.10) moisture content a t the f i r s t week whereas the m i l d l y d e f i c i e n t b i r d s had a s i g n i f i c a n t l y lower(p<0.lO)moisture content than c o n t r o l s a f t e r four weeks of treatment. Isometric tension parameters a) Time to maximum tension Samples from t r e a t e d b i r d s g e n e r a l l y required longer t o develop maximum isometric tension than samples from the c o n t r o l s but t h i s d i f f e r e n c e was s i g n i f -i c a n t (p<0.10) only f o r d e f i c i e n t b i r d s a f t e r 2 weeks on the a v i t a m i n o t i c A r a t i o n and f o r those b i r d s which were m i l d l y d e f i c i e n t a f t e r four weeks (Table X). Samples from c o n t r o l b i r d s in the fourth treatment week required s i g n i f i c a n t l y less time to reach maximum tension than those c o n t r o l s of the Table X: Means and standard e r r o r s of time and tension development postmortem f o r s t r i p s of White Leghorn cockerel P. major muscle run in phosphate b u f f e r . Time t o Maximum Tension (minutes) Maximum Isometric Tension (qm/cm ) Duration of Treatment Control D e f i c i e n t M i l d l y d e f i c i e n t Control D e f i c i e n t M i l d l y d e f i c i e n t ( i n weeks) 1 272.2 + 40.9aA 295.2 + 29.4aA* 96.66 + 9.2aA 84.64 + 7.2aA 2 244.4 + 50.5aA 391 .1 + 35. IbB 82.10 + 7.8aA 88.44 + 8.8aA 3 266.5 + 40.4aA 261 .4 + 45.9aA 290.7 + 40.7aA 83.15 + 5.0aA 90.09 + 7.1aA 94.44 + 6.4aA 4 175.2 + 36.0aB 300.8 + 78.1aA 375.0 + 83.5bA 80.95 + 7.1aA 77.16 + 6.0aA 80.93 + 7.4aA 5 212.4 + 38.0aA 296.2 + 58.6aA 320.8 + 76.7aA*. 73.21 + 3.9aB 100.22 + 3.9bB 99.50 + 6.4bA 1 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 2 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean at Week 1 ( (p<0.10) 25 f i r s t week (p<0.10). The average time to maximum tension f o r the d e f i c i e n t b i r d s sampled in the second week was s i g n i f i c a n t l y longer (p<0.10) than f o r those sampled in the f i r s t week, b) Maximum isometric tension Vitamin A d e p r i v a t i o n d i d not appear t o influenc e the maximum isometric tension developed in the e a r l y stages of d e f i c i e n c y . ( T a b l e X). A f t e r f i v e weeks of treatment however, d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s developed s i g n i f i c a n t l y greater maximum tension than c o n t r o l s (p<0.10). The f i f t h week value f o r d e f i c i e n t b i r d s was a l s o s i g n i f i c a n t l y higher than t h a t developed by d e f i c i e n t b i r d s a t week 1 (p<0.10). When the data was subjected to regression a n a l y s i s a s i g n i f i c a n t negative c o r r e l a t i o n c o e f f i c i e n t of r = -.896 (p<0.02) was obtained f o r the co n t r o l group. No r e l a t i o n s h i p between maximum tension and age could be e s t a b l i s h e d f o r the treatment group. P. major metabolite l e v e l s a) ATP Elevated P. major ATP l e v e l s appear in the f i r s t four weeks of vitamin A d e f i c i e n c y and f o r the d e f i c i e n t b i r d s of the second week t h i s d i f f e r e n c e i s s i g n i f i c a n t (p<0.10) (Table X I ) . Nbcother treatment or time e f f e c t i s i n d i c a t e d . b) Glycoqen D e f i c i e n t b i r d s of the f i r s t week had s i g n i f i c a n t l y greater t i s s u e glycogen l e v e l s than c o n t r o l s (p<0.10) but no other treatment e f f e c t can be observed. The c o n t r o l s of the second week had s i g n i f i c a n t l y greater glycogen values and the d e f i c i e n t b i r d s of the f i n a l week had s i g n i f i c a n t l y lower glycogen values than t h e i r r e s p e c t i v e f i r s t week values (p<0.10). Table XI: Means and standard e r r o r of P. major,.ATP and glycogen l e v e l s ATP(jumoles/gm) Glycogen (jumoles glucose/gm); Vitamin A d e f i c i e n t Vitamin A d e f i c i e n t Duration of Treatment ( i n weeks) Control D e f i c i e n t M i l d l y d e f i c i e n t Control D e f i c i e n t M i l d l y d e f i c i e n t 1 6.08 + 0.6aA 7.57 + L l a A 1 7.92 + 0.4aA 11.58 + 1.6bA 2 5.78 + 0.7aA 7.92 + 0.4bA 11.42 + 1.5aB 11.61 + l . l a A 3 5.78 + 0.9a A 6.46 + 0.8aA 6.98 ± 0.7aA 9.22 + 0.8aA 8.15 + 1.3aA/ 8.83 + 1.2aA 4 5.26 + 0.9aA 5.32 + 0.9aA 6.14 ± :1.0aA 8.78 + l . l a A 9.07 + 1.8aA 9.60 + 2.4aA 5 7.56 + 0.9a A 5.83 + 0.6aA 6.20 ±.0.8aA 9.01 + 0.9aA 7.82 + l . l a B 6.88 + 1.4aB 1 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 2 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 1 (p<0.10) 27 Shear values The e f f e c t of vitamin A d e f i c i e n c y on shear value i s presented in Table X I I . No s t a t i s t i c a l d i f f e r e n c e s in shear value were evident u n t i l the f i f t h treatment week when d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s had s i g n i f -i c a n t l y greater shear values than c o n t r o l s (p<0.10). Control and treatment groups a l l indicated a general trend of inc r e a s i n g shear with i n c r e a s i n g age. S i g n i f i c a n t regression c o e f f i c i e n t s of r = .839 (p<0.05), r = .963 (p<0.005)and r = .911 (p<0.02) were c a l c u l a t e d f o r the c o n t r o l , d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s r e s p e c t i v e l y . S i g n i f -i c a n t regression c o e f f i c i e n t s of r = .955 (p<0.005) and r = .920 (p<0.01) were obtained f o r d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s when shear was expressed as kg/cm^. A simple c o r r e l a t i o n a n a l y s i s was performed on the data obtained f o r the P. major muscle and the c o r r e l a t i o n matrix f o r the c o n t r o l and f o r the d e f i c i e n t group i s presented in Table XIII and Table XIV r e s p e c t i v e l y . In the con t r o l group, there was a s i g n i f i c a n t c o r r e l a t i o n between the time t o maximum tension and ATP, as well as between the maximum tension developed and shear value. In the d e f i c i e n t group the time t o maximum tension was s i m i l a r l y s i g n i f i c a n t l y c o r r e l a t e d with ATP; a d d i t i o n a l l y i t e x h i b i t e d a s i g n i f i c a n t a s s o c i a t i o n with glycogen. The d e f i c i e n t group showed a s i g n i f i c a n t c o r r e l a t i o n between ATP and glycogen and between ATP and shear value. Both are s i g n i f -i c a n t l y d i f f e r e n t than those a s s o c i a t i o n s between the same parameters of the cont r o l group (p<0.05). Table XII:. Means and standard e r r o r s of shear values f o r White Leghorn cockerel P. major kg kg/cm' Vitamin A d e f i c i e n t Vitamin A d e f i c i e n t Duration of Treatment Control D e f i c i e n t M i l d l y d e f i c i e n t Control D e f i c i e n t M i l d l y d e f i c i e n t ( i n weeks) 1 1 .82 + 0 . 2 a A 1 . 89 + 0 . 2 a A i , 3 . 04 + 0 . 3 a A 3 . 1 7 + 0 . 3 a A 2 1 .97 + 0 . laA 1.91 + O.laA 3 . 2 9 + 0 . 2 a A 3 . 1 9 + 0 . laA 3 2 . 0 6 + 0 . laA 2 . 3 5 + 0 . 4 a A 1 .99 + 0 . 2 a A 3 . 4 3 + 0 . 3 a A 3 . 92 + 0 . 7 a A 3 . 32 + 0 . 3 a A 4 2 . 4 0 + 0 . 2 a B 2 . 4 0 + 0 . 2 a A 2 . 3 0 + 0 . 2 a A 3 . 9 9 + 0 . 3 a B 4 . 0 0 + 0 . 3 a B 3 . 84 + 0 . 4 a A 5 2 . 1 9 + 0 . 2 a A 2 . 6 9 + 0.2bB 2 . 78 + O.IbB 3.51 + 0 . 4 a A 4.33 + 0.2bB 4 . 4 8 + 0.3bB 1 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0 . 10 ) 2 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean at Week 1 (p< 0 . 1 0 ) CO 29 Table X I I I : C o r r e l a t i o n matrix f o r parameters studied in Experiment 2, co n t r o l b i r d s TMT MT ATP Glycogen Shear (kg) Shear (kg/cm ) TMT MT ATP Gl ycogen Shear (kg) ^ Shear (kg/cm ) 1.000 -0.097 0.359* 0.179 -0.185 -0.168 1 .000 -0.131 -0.119 -0.317* -0.294 1 .000 -0.274 0.019 0.003 1 .000 0.044 0.038 1 .000 0.992** 1 .000 * p<0.05 ** p<0.01 Table XIV: C o r r e l a t i o n matrix f o r parameters studied in E x p e r i m e n t s , treatment b i r d s TMT MT ATP Glycogen Shear (kg) TMT 1 .000 MT 0.236 1.000 ATP 0.542** 0.249 1 .000 Gl ycogen 0.343* 0.236 0.533** 1.000 Shear (kg) ^ -0.244 -0.191 -0.383* -0.295 1.000 Shear (kg/cm ) -0.246 -0.221 -0.381* -0.285 0.996** Shear (kg/cm ) 1.000 * p<0.05 ** p<0.01 30 L i v e r glycogen and vitamin A When c a l c u l a t e d on per gram dry matter b a s i s , l i v e r glycogen was s i g n i f i c a n t l y greater (p<0.10) f o r d e f i c i e n t b i r d s of the four t h treatment week when compared t o c o n t r o l s (Table XV). M i l d l y d e f i c i e n t b i r d s had s i g n i f i c a n t l y higher l i v e r glycogen than c o n t r o l s (p<0.10) only a f t e r f i v e weeks on the avit a m i n o i c A r a t i o n though an elevated level was noted in the four t h treatment week. D e f i c i e n t b i r d s of the fourth and m i l d l y d e f i c i e n t b i r d s of the f i f t h treatment week both maintained s i g n i f i c a n t l y d i f f e r e n t values when glycogen l e v e l s were expressed as percent t o t a l dry l i v e r ; the m i l d l y d e f i c i e n t b i r d s of the four t h week had s i g n i f i c a n t l y higher percent l i v e r glycogen l e v e l s than c o n t r o l s (p<0.10). The e f f e c t of d i e t a r y vitamin A on hepatic vitamin A sto r e s i s a l s o presented in Table XV. Those c h i c k s r e c e i v i n g the vitamin A d e f i c i e n t r a t i o n had lower hepatic stores than c o n t r o l b i r d s a t each treatment stage. No trend was in d i c a t e d f o r the tre a t e d b i r d s , but a gradual increase in l i v e r vitamin A was noted f o r the c o n t r o l b i r d s from 6 through 8 weeks of age, a f t e r which a plateau was reached. Table XV: The e f f e c t of vitamin A d e f i c i e n c y on l i v e r glycogen and vitamin A content Glycogen (jumoles glucose/gm dry weight) Glycogen (Percent t o t a l dry l i v e r ) Vitamin A Vitamin A d e f i c i e n t Vitamin A d e f i c i e n t (lU/gm dry wt) Duration of Treatment Control D e f i c i e n t Mi Idly d e f i c i e n t Control D e f i c i e n t M i l d l y ^ d e f i e i e n t v C o n t r o l D e f i c i e n t ( i n weeks) 1 253. 8±25 • 7aA 243.8±25.9aA^ 4.57±0.5aA 4 .39±0. 5aA 46.7±7.2 6.910.8 2 232. 4±41 .4aA 263.0+55.3aA 4.18±0.6aA 4 •73±1. OaA 117.616.4 6.110.8 3 257. 5±51 • OaA 239.0±59.2aA 236.8±59.2aA 4.62±0.9aA 4 .30±0. 9aA 4.30±1 . laA 136.2±6.2 4.912.7 4 188. 3±34 .3aA 379.1±69.9bB 333.0±89.5aA 3.39±0.5aA 6 . 82±.1. 1 bB 6.12±1 • 3bA 147.5±6.2 1.610.4 5 272. 1 ±28 .3aA 318.4±65.0aA 403.0±75.7bB 4.90±0.5aA 5 .7311. 2aA 7.25±1 • 4bB 136.012.4 3.210.7 1 mean and standard e r r o r 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 3 means in same comumn followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 1 (p<0.10) 32 Experiment 3  M o r t a l i t y rate In Experiment 3 the m o r t a l i t y rate in the f i r s t f i v e weeks p r i o r to d i e t a l l o c a t i o n was r e l a t i v e l y low at 1.9$. By the end of the seven week experimental pe r i o d , 3.8$ of the c o n t r o l b i r d s died whereas the group r e c e i v i n g the treatment r a t i o n experienced a 34.6$ reduction. Notably, the l a r g e r number of deaths occurred during the f i f t h and s i x t h treatment weeks f o r which m o r t a l i t y rates of 23.1$ and 5.8$ were recorded. Body weight No s i g n i f i c a n t d i f f e r e n c e s in weekly body weight were observed between con t r o l and vitamin A d e f i c i e n t b i r d s from 5 through 9 weeks of age; however, tr e a t e d b i r d s were s i g n i f i c a n t l y l i g h t e r (p<0.10) than c o n t r o l s at 10, 11 and 12 weeks of age (Table XVI). S i m i l a r trendsswere noted in the weekly and terminal body weights of the sampled b i r d s , but the terminal weights of those a v i t a m i n o t i c A b i r d s s a c r i f i c e d a t 9 weeks of age were a l s o s i g n i f i c a n t l y l i g h t e r (p<0.10) than c o n t r o l s . Feed e f f i c i e n c y Feed e f f i c i e n c y values f o r those b i r d s sampled at each treatment stage are presented in Table XVII. The two columns appearing under the experimental heading are designated as d e f i c i e n t and m i l d l y d e f i c i e n t . These two groups were e s t a b l i s h e d according t o the manner described in Experiment 2. A d d i t i o n a l l y , b i r d s sampled during the f i r s t and second weeks of r e p l e t i o n were designated m i l d l y d e f i c i e n t i f they had a net p o s i t i v e weight gain, though some b i r d s had p r e v i o u s l y experienced weight l o s s . Feed e f f i c i e n c y values were markedly influenced by treatment; d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s had s i g n i f i c a n t l y ! l o w e r (p<0.10) feed e f f i c i e n c y Table XVI: Means and standard e r r o r s of body weight (Experiment 3) Weekly Weight Weekly Weight Terminal Weight of B i r d s Used of Sampled B i r d s of Sampled B i r d s Duration of Control Experimental Control Expermintal Control Experimental Age Treatment^ (gm) (gm) (gm) (gm) (gm) (gm) ( i n weeks) ( i n weeks) 5 0 320 + 8.0a 309 + L'6.4a 6 AD 467 + 11.4a 456 + r911a 7 2D 566 + 14.4a 571 + 10.4a 8 3D 710 + 15.4a 700 + 13.0a 9 4D 821 + 21.2a 778 + 18.6a 882 + 37.6a 786 + 35.1a 952 ± 39.'7a 807 + 4,1.5b 10 5D 988 + 26.0a 844 + 27.0b 1045 + 37.1a 842 + 50.6b 1097 ± 44.3a 861 + 57.2b 11 IR 1 106 + 35.5a 870 + 40.9b 1159 + 35.4a 913 + 75.6b 12.1-3 ± 35.8a 934 + 85.3b 12 2R 1 158 + 64.8a 951 + 24.2b 1158 + 64.7a 951 + 24.2b 1182 ± 77.6a 988 + 16Hb 1 D, R i n d i c a t e d e p l e t i o n and r e p l e t i o n as described in t e x t 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.05) 34 values a t each treatment stage. Control and treatment b i r d s showed decreasing feed e f f i c i e n c y with i n c r e a s i n g age and when the data were subjected t o regression a n a l y s i s , s i g n i f i c a n t regression c o e f f i c i e n t s of r = -.985 (p<0.005), r = -.959 (p<0.02) and r = -.986 (p<0.005) were c a l c u l a t e d f o r the c o n t r o l , d e f i c i e n t and ml Idly d e f i c i e n t b i r d s r e s p e c t i v e l y . Table XVII: The e f f e c t of vitamin A on feed e f f i c i e n c y (Experiment 3) Feed E f f i c i e n c y (gm/gm feed consumed) 0 ! tr r - j Experimental Age Duration of ( i n Treatment. Control D e f i c i e n t M i l d l y d e f i c i e n t weeks) ( i n weeks) 9 4D 0.403 ± 0.021aA 0.345 ± 0.015bA^ 0.359 ± 0.007bA 10 5D 0.386 ± 0.015aA 0.288 ± 0.018bB 0.313 ± 0.017bB 11 1R 0.340 ± O.OIlaB 0.271 ± 0.025bB 0.296 ± 0.024bB 12 2R 0.300 ± 0.020aB 0.249 ± 0.007bBB 1 as in Table XVI 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 3 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 4 (p<0.10) L i v e r weight and moisture content On a gram weight basis d e f i c i e n t b i r d s had s i g n i f i c a n t l y l i g h t e r l i v e r weights (p<0.10) than c o n t r o l s at 9, 10 and 11 weeks of age (Table X V I I I ) ; m i l d l y d e f i c i e n t b i r d s had s i g n i f i c a n t l y l i g h t e r (p<0.10) l i v e r weights than c o n t r o l s a t 9 and 10 weeks of age. Compared t o the average l i v e r weight at 9 weeks of age, s i g n i f i c a n t increases in l i v e r weight were observed f o r 11 and 12 week-old t r e a t e d birds.(p<0.10). No s i g n i f i c a n t d i f f e r e n c e s were noted between c o n t r o l group b i r d s . 35 Table XVIII: Means and standard e r r o r s of l i v e r weight and moisture content (Experiment 3) Experimental Age Duration of ( i n Treatment. Control D e f i c i e n t M i l d l y d e f i c i e n t weeks) ( i n weeks) L i v e r Weight (gm) 9 4D 26.7 ± 1.5aA 19.9 ± 1.2bA* 20.8 + 0.8bA 10 5D 29.2 ± 0.9aA 20.9 ± 1.4bA 22.8 + 1 .6bA 11 1R 28.4 ± I.OaA 24.1 ± .1 -5bB- 25.3 + 1.7aB 12 2R 27.0 ± 1.5aB 24.9 ± l . l a B L i v e r Weight (as ? 5 body weight) 9 4D 2.79 ± 0.2aA 2.46 ± O.laA 2.48 + 0.1aA 10 4D 2.61 ± O.laA 2.40 ± O.laA 2.38 + 0.2aA 11 1R 2.35 ± O.laB 2.71 ± 0.3aA 2.60 _± 0.4aA 12 2R 2.23 ± 0.1aB 2.52 ± 0:ibA L i v e r moisture content 9 4D 0.698 ± 0.011aA 0.706 ± 0.008aA 0.704 ± 0.008aA 10 5D 0.666 ± 0.019aA 0.702 + 0.015aA 0.693 ± 0.023aA 11 IR 0.701 ± 0.006aA 0.701 ± 0.014aA 0.682 ± 0.008aB 12 2R 0.702 ± 0.007aA 0.707 ± 0.005aA 1 as in Table XVI 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t ! (p<0.10) 3 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t ! from mean of Week 4 (p<0.10) 36 Expressed as percent body weight, l i v e r weights were not s i g n i f i -c an t l y d i f f e r e n t u n t i l 12 weeks of age when d e f i c i e n t b i r d s had s i g n i f i c a n t l y g rea te r l i v e r weight va lues - than c o n t r o l s (p<0.10). In con t r o l b i r d s , l i v e r weight as percent body weight decreased wi th i nc rea s i ng age and a s i g n i f i c a n t regres s ion c o e f f i c i e n t o r r = -.991 (p<0.002) was obta ined f o r t h i s group. No d e f i n i t e t rend was i nd i ca ted f o r the t rea ted groups. No s i g n i f i c a n t d i f f e r e n c e s were noted wi th respect to l i v e r moisture content . I sometr ic tens ion parameters a) Time to maximum tens ion P. major samples from b i r d s of the t r ea ted group requ i red longer to develop i somet r i c tens ion than samples from c o n t r o l s a t 10 and 11 weeks of age (Table XIX). D e f i c i e n t and m i l d l y d e f i c i e n t 11 week-old b i r d s showed s i g -n i f i c a n t l y extended times to maximum tens ion when compared to c o n t r o l s (p<0.10); they were a l s o s i g n i f i c a n t l y s lower in reaching maximum tens i on than t r ea ted b i rd s a t 9 weeks of age (p<0.10). No s t a t i s t i c a l d i f f e r e n c e s were noted between the d e f i c i e n t and the m i l d l y d e f i c i e n t b i rd s of a p a r t i c u l a r t reatment stage; however, m i l d l y d e f i c i e n t b i rd s had nominal ly e levated times to maximum tens ion when compared to t h e i r r e spec t i ve d e f i c i e n t b i r d s . b) Maximum tens ion D e f i c i e n t b i rd s developed s i g n i f i c a n t l y g rea te r maximum tens i on than c o n t r o l s a t 10 and 11 weeks of age (p<0.10), whereas m i l d l y d e f i c i e n t b i rd s developed s i gn i fji cant I y g rea te r tens ion than c o n t r o l s (p<0.10) only a t 11 weeks of age. The va lues f o r d e f i c i e n t 11 week-old b i r d s were a l s o s i g n i f i -c a n t l y h igher (p<0.10) than those develeped by t h e i r r e spec t i ve groups at 9 weeks of age. Table XIX: Means and standard e r r o r s of time and tension development postmortem f o r s t r i p s of White Leghorn cockerel P. major muscle run in phosphate b u f f e r . Time t o Maximum Tension (minutes) Maximum Isometric Tension (gm/cm ) Experimental Experimental Age ( i n weeks) Duration of Treatment^ ( i n weeks) Contro1 Def i c i e n t M i l d l y def i c i e n t Control Def i c i e n t M i l d l y d e f i c i e n t 9 4D 232.8±42.9aA 238.5134.2aA!l 243.4±39.1aA 81.05110.7aA 89.2H5.2aA 87.67i5.8aA 10 5D 199.8±45.8aA 299.6159.4aA 320.6±55.6aA 76.871 4-3aA 89.64i6.4bA 85.02l8.2aA 11 IR 201.1±41.6aA 376.1155.6bB 426.5±59.7bB 81.291 4.7aA 113.61l8.4bB 106.3219.4bA 12 2R 258.7±22.7aA 259.4164.OaA- 79.381 7.3aA 84.50±5.8aA 1 D, R as in Table XVI 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 3 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 4 (p<0.10) 38 P. major metabolite l e v e l s a) ATP No s i g n i f i c a n t d i f f e r e n c e s o r recognizable trends were i n d i c a t e d f o r P. major ATP values (Table XX). b) Glycoqen D e f i c i e n t and m i l d l y d e f i c i e n t 9 week-old b i r d s had s i g n i f i c a n t l y higher t i s s u e glycogen values than c o n t r o l s (p<0.10); higher glycogen l e v e l s were a l s o noted f o r the tre a t e d b i r d s a t 10 and 11 weeks of age (Table XX). S l i g h t l y elevated l e v e l s were observed when m i l d l y d e f i c i e n t b i r d s at 9, 10, and 11 weeks of age were compared t o d e f i c i e n t b i r d s at the same stage of treatment but no s t a t i s t i c a l d i f f e r e n c e s were evident. A d e f i n i t e trend of in c r e a s i n g t i s s u e glycogen with i n c r e a s i n g age was observed f o r co n t r o l b i r d s and a s i g n i f i c a n t regression c o e f f i c i e n t of r = .916 (p<0.05) was c a l c u l a t e d . Shear value D e f i c i e n t b i r d s a t 10 weeks of age and m i l d l y d e f i c i e n t b i r d s a t 11 weeks of age demonstrated s i g n i f i c a n t l y greater shear values (kg) than t h e i r r e s p e c t i v e c o n t r o l s (p<0.10) (Table XXI). This pattern was maintained when 2 shear value was expressed as kg/cm , though d e f i c i e n t b i r d s were a d d i t i o n a l l y s i g n i f i c a n t l y tougher than c o n t r o l s a t 11 weeks of age (p<0.10). A simple c o r r e l a t i o n a n a l y s i s was performed on the data obtained f o r the P. major muscle. As no s i g n i f i c a n t a s s o c i a t i o n s between any of the parameters were obtained f o r the c o n t r o l group, the c o r r e l a t i o n matrix f o r t h i s group i s not presented. The c o r r e l a t i o n matrix f o r the d e f i c i e n t group i s presented in Table XXII. Table XX: Means and standard e r r o r s of P. major ATP and glycogen l e v e l s ATP (jumoles/gm) Glycogen (jumoles glucose/gm) Age ( i n weeks) Duration of Treatment^ ( i n weeks) Control Def i c i e n t M i l d l y def i c i e n t Control Def i c i e n t Mi Idly def i c i e n t 9 4D 4.99±0.7aA 6.02±0.6aA2 5.81±0.6aA 5.36±0.6aA 9.51±1.4bA 9.64±1.6bA 10 5D 5.88±0.7aA 5.80±0.8aA 6.,T9±1.4aA 8.72±1.2aB 11.32±2.5aA 14.12±4.0aA 11 1R 6.75±0.6aB 6.34±0.8aA 6.78±0.9aA 8.51±0.8aB 9.98±1.7aA 11.32±2.0aA 12 2R 6.07±0.2aA 4.78±0.7aA 10.42±1.0aB 8.83±0.6aA 1 D, R as in Table XVI 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 3 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 4 (p<0.10) U J VO Table XXI: Means and standard e r r o r s of shear values f o r White Leghorn cockerel P. major Shear (kg) Shear (kg/cm ) Exper imenta I <:2. _ r i Exper imenta I Age ( i n weeks) Duration of Treatment^ ( i n weeks) Control D e f i c i e n t Mi Idly d e f i c i e n t Control Def i c i e n t M i l d l y def i c i e n t 9 4D 2.12±0.2aA 2.45±0.8aA^ 3.28±0.6aA 3.68±1.1aA 10 5D 1.92±0.2aA 2.44±0.2bA 2.31±0.2aA 3.08±0.2aA 3.95±0.3bA 3.70±0.4aA 11 IR 1.98±0.1aA 2.28±0.2aA 2.42±0.2bA 3.05±0.1aA 3.87±0.3bA 3.79±0.4bA 12 2R 2.23±0.2aA 2.37±0.1aA 3.37±0.3aA 3.75±0.2aA 1 as in Table XVI 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<.0.10) 3 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 4 (p<0.10) o 41 In the d e f i c i e n t group, there was a s i g n i f i c a n t c o r r e l a t i o n between the time to maximum tension and glycogen, as well as between ATP and shear valuev No other s i g n i f i c a n t a s s o c i a t i o n s are evident. Table XXII: C o r r e l a t i o n matrix f o r parameters studied in Experiment 3, • treatment b i r d s TMT MT ATP Glycogen Shear (kg) Shear (kg/cm ) TMT MT ATP GIycogen Shear (kg) ^ Shear (kg/cm ) 1.000 0.115 0. 184 0.470** -0.049 -0.107 1 .000 0.191 -0.061 -0.135 -0.109 1.000 0.168 -0.398* -0.527** 1 .000 .,-0.060 -0.132 1 .000 0.904** 1.000 * p<0.05 ** p<0.01 L i v e r glycogen and vitamin A When c a l c u l a t e d on per gram dry matter b a s i s , s l i g h t l y elevated l i v e r glycogen values were noted f o r d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s at 9 and 10 weeks of age, and the d i f f e r e n c e s between the glycogen values of m i l d l y d e f i c i e n t b i r d s and c o n t r o l s were greater than those between c o n t r o l s and d e f i c i e n t b i r d s . At 11 weeks of age lowered l i v e r glycogen values were observed f o r d e f i c i e n t b i r d s , whereas m i l d l y d e f i c i e n t b i r d s and c o n t r o l s had s i m i l a r glycogen l e v e l s . A s i m i l a r pattern was displayed when l i v e r glycogen i s expressed as percent t o t a l dry l i v e r . L i v e r glycogen was not s i g n i f i c a n t l y influenced by vitamin A d e f i c i e n c y or vitamin A r e p l e t i o n (Table X X I I I ) . An age-dependent decrease in l i v e r glycogen storage was observed f o r c o n t r o l and m i l d l y d e f i c i e n t b i r d s . S i g n i f i c a n t regression c o e f f i c i e n t s 42 of r = -.966 (p<0.01) and r = -.947 (p<0.02) were c a l c u l a t e d f o r c o n t r o l and m i l d l y d e f i c i e n t b i r d s r e s p e c t i v e l y when l i v e r glycogen was expressed as jumoles/gm dry matter. Hepatic vitamin A s t o r e s were d r a m a t i c a l l y a f f e c t e d by d i e t a r y vitamin A . D e f i c i e n t b i r d s at 9 and 10 weeks of age had markedly reduced l e v e l s when compared to c o n t r o l s . When p r e v i o u s l y d e f i c i e n t b i r d s received the vitamin A-adequate r a t i o n f o r a 2 week period, there was a gradual increase in l i v e r vitamin A s t o r e s , though the l e v e l s in the repleted b i r d s remained lower than the co n t r o l avalues. 43 Table XXIII: The e f f e c t of vitamin A on l i v e r glycogen and vitamin A ExperimentaI Duration of Age Treatment, Control D e f i c i e n t M i l d l y d e f i c i e n t ( i n weeks) ( i n weeks) L i v e r glycogen (umoles qlucose/q m dry weiqht 9 4D 310.8 ± 57.2aA 355. 1 ±151.5aA? 389.8 + 44.0aA 10 5D 283.6 + 15.7aA 300.5 + 53.1aA 353.9 + 60.9aA 11 IR 248.0 ± 22.6aA 206.2 + 56.9aB 254.0 + 64.7aA 12 2R 243.2 ± 41.2aA 250.6 + 15.0aB L i v e r glycogen (Percent t o t a l dry 1 i v e r ) 9 4D 5.58 ± • 0V7aA 6.41 + 0.9aA 7.04 + 0.8aA 10 5D 5.08 ± 0.2aA 5.41 + I.OaA 6.37 + 1. 1aA 1 1 IR 4.46 ± 0.4aA 3.71 + 1 .OaB 4.59 + 1.2aA 12 2R 4.38 ± 0.7aA 4.51 + 0.3aA Vitamin A (1U/qm dry wt.) 9 4D 160.5 ± 11.3 4.4 + 1.5 .10 5D 143.0± ±1.1.4 3.7 + 0.5 11 1R 186.0 ± 11.7 31.4 + 1.0 12 2R 151.6 ± 2.4 75.7 + 1 .5 1 as in Table XVI 2 means in same row followed by s i m i l a r lower case l e t t e r s do not d i f f e r s i g n i f i c a n t l y (p<0.10) 3 means in same column followed by s i m i l a r c a p i t a l l e t t e r s do not d i f f e r s i g n i f i c a n t l y from mean of Week 4 (p<0.10) 44 DISCUSSION Experiment 1 was conceived as a p r e l i m i n a r y study t o i d e n t i f y the d i e t formulation best s u i t e d f o r subsequent s t u d i e s and t o execute and evaluate the a n a l y t i c a l techniques. The data in d i c a t e d s i g n i f i c a n t l y l i g h t e r body weight f o r the 8 week-old b i r d s which received 375 IU vitamin A/kg and s i g n i f i c a n t l y l i g h t e r l i v e r weights f o r the b i r d s maintanined on the two lowest l e v e l s of vitamin A supplementation (373 and 750 lU/kg). However, as no s i g n i f i c a n t d i f f e r e n c e s or recognizable trends were in d i c a t e d f o r any of the other parameters examined, t h i s study w i l l not be dicussed f u r t h e r . The extremely high m o r t a l i t y r a t e encountered in the f i r s t week of Experiment 2 i s d i f f i c u l t to e x p l a i n but as no f u r t h e r deaths were recorded in the four week period p r i o r t o treatment a l l o c a t i o n , the s u r v i v i n g b i r d s were considered s u i t a b l e f o r subsequent study. This may not have been a v a l i d assumption as some c o n t r o l and vitamin A d e f i c i e n t b i r d s e x h i b i t e d symptoms of Newcastle disease (coughing, breathing with a r a t t l i n g sound, weak necks) during the second week of treatment. This occurrance and the implemented v a c c i n a t i o n procedure complicate the i n t e r p r e t a t i o n of the data obtained -data r e f l e c t i n g a n u t r i t i o n a l s t r e s s as well as one due to i n f e c t i o n . No evidence of Newcastle disease was noted f o r those b i r d s of Experiment 3 but they a l s o received v a c c i n a t i o n s . In both experiments the m o r t a l i t y rates of the c o n t r o l b i r d s were less than those of the corresponding t r e a t e d b i r d s and, as expected, the highest m o r t a l i t y rates f o r the l a t t e r were noted in the l a t e r stages of d e f i c i e n c y . The e f f e c t of feeding a vitamin A adequate r a t i o n t o p r e v i o u s l y d e f i c i e n t b i r d s was studied in Experiment 3 and i t would appear th a t a s i n g l e week of r e p l e t i o n 45 was not s u f f i c i e n t to overcome the e f f e c t s of a f i v e week period of d e f i c i e n c y : the second highest m o r t a l i t y rate of t h i s study was recorded at t h i s time. Both experiments i n d i c a t e t h a t a v i t a m i n o s i s A does not a f f e c t body weight gain during the e a r l y stages but s i g n i f i c a n t l y depresses growth as the d e f i c i e n c y progresses. Harms et aj_. (1955) reported t h a t there was no d i f f e r -ence in the average weight of 4 week-old b i r d s fed 500 IU compared t o t h a t of con t r o l b i r d s which received 4000 IU, while Nockels e t a]_. (1973) reported s i g n i f i c a n t l y l i g h t e r body weights f o r vitamin A d e f i c i e n t b i r d s a t 5, 6 and 7 weeks of age. Dorr and Balloun (1976) confirmed t h i s growth depression in a v i t a m i n o t i c A turkeys of both sexes and f u r t h e r suggested t h a t males may be more s e n s i t i v e to vitamin A treatments. Any di s c r e p a n c i e s among these f i n d i n g s may be a t t r i b u t e d t o v a r i a t i o n s in the s e v e r i t y of vitamin A r e s t r i c t i o n and in the stage of development when treatment was i n i t i a t e d . The lag observed in response to vitamin A r e p l e t i o n was not unexpected. Johnson and Wolf (1960) suggested t h a t only the changes observable in a i mi Id d e f i c i e n c y should be thought i n d i c a t i v e of the real metabolic f u n c t i o n of vitamin A and t h i s view has received support from several other workers. (Nockels and P h i l l i p s 1971 a + b., Bcuckenta I e t aj_. 1974 and Krause et aj_. 1975) The actual c l a s s i f i c a t i o n of which d e f i c i e n c y s t a t e the data presented herein represents, u t i I ized the ca t e g o r i e s proposed by Krause e_f aj_. (1975) who suggested that r a t s were severely d e f i c i e n t when they no longer gained or began to lose weight but m i l d l y d e f i c i e n t when weight gain decreased with respect to c o n t r o l values. For the purpose of t h i s study, the ' d e f i c i e n t ' group (as in d i c a t e d p r e v i o u s l y ) includes both severely and m i l d l y d e f i c i e n t bi rds. Feeding a vitamin A d e f i c i e n t r a t i o n lowered feed e f f i c i e n c y and 46 t h i s decrease was s i g n i f i c a n t f o r the tr e a t e d b i r d s of Experiment 3. In both experiments, the feed e f f i c i e n c y values f o r m i l d l y d e f i c i e n t b i r d s f e l l between those f o r c o n t r o l and d e f i c i e n t b i r d s . Both st u d i e s i n d i c a t e d a d e f i n i t e trend of decreasing feed e f f i c i e n c y with i n c r e a s i n g age f o r a l l three groups of b i r d s . Singh and Donovan (1973) suggested t h a t a reduction in feed u t i l i z a t i o n was due to a lowered absorption of n u t r i e n t s , a normal absorption followed by i n e f f i c i e n t metabolic use or a combination of both. The e f f e c t of vitamin A d e f i c i e n c y on l i v e r weight appears s i m i l a r to i t s e f f e c t on body weight, with l i t t l e or no e f f e c t in the e a r l i e r stages and a s i g n i f i c a n t depression f o r both d e f i c i e n t and m i l d l y d e f i c i e n t b i r d s a f t e r f i v e weeks of d e p l e t i o n . The response t o refeeding of a vitamin A adequate r a t i o n however was quicker than t h a t of body weight r e s u l t i n g in s i m i l a r l i v e r weight values f o r c o n t r o l and m i l d l y d e f i c i e n t b i r d s . a f t e r one week of r e p l e t i o n . When l i v e r weight was expressed as percent body weight t h i s e f f e c t of r e p l e t i o n was accentuated. Treated and co n t r o l b i r d s showed the expected pattern of incr e a s i n g l i v e r weight with i n c r e a s i n g age in Experiment 2, but t h i s pattern was not as c l e a r l y defined in Experiment 3 as the sampled b i r d s were o l d e r . The f i n d i n g s of the present study support the observation by " Krause e t aj_. (V975) t h a t r e t i n o I d e f i c i e n t r a t s had decreased l i v e r weights. When expressed as percent body weight however, severely d e f i c i e n t r a t s had s i g n i f i c a n t l y l a r g e r l i v e r s while m i l d l y d e f i c i e n t ones d i d not d i f f e r s i g n i f -i c a n t l y from c o n t r o l s . This n o n s i g n i f i c a n t l i v e r weight response has a l s o been observed in m i l d l y d e f i c i e n t chickens (Nockels and P h i l l i p s 1971a). L i v e r moisture content i s not a f f e c t e d by vitamin A d e f i c i e n c y . No e f f e c t of vitamin A d e f i c i e n c y on t o t a l body water, expressed as percent 47 body weight, was found e i t h e r in r a t s (Mahant and Eaton 1976) or in chickens (Lopez e t aj_. 1973), although n e i t h e r of these s t u d i e s examined the moisture content of s p e c i f i c Organs. There was a d e f i n i t e i n f l u e n c e of vitamin A d e f i c i e n c y on hepatic carbohydrate metabolism and the response appears r e l a t e d t o the progress of the d e f i c i e n c y . M i l d hypovitaminosis A :i,nduces an increase in glycogen d e p o s i t i o n whereas a severe d e f i c i e n c y leads t o a reduction of these elevated s t o r e s . The e f f e c t i s more apparent in Experiment 3 where the r e s u l t s are not masked by the s t r e s s of i n f e c t i o n . The lowered l i v e r glycogen value observed f o r the d e f i c i e n t b i r d s during the f i r s t week of r e p l e t i o n r e f l e c t s the con-t r i b u t i o n of those b i r d s which lagged in t h e i r response to a vitamin A adequate r a t i o n and maintained a severely d e f i c i e n t s t a t u s . On the other hand, m i l d l y d e f i c i e n t b i r d s responded very r a p i d l y and e x h i b i t e d near normal values f o r the e n t i r e r e p l e t i o n p e r i o d , though they retained s l i g h t l y elevated glycogen l e v e l s when expressed as percent t o t a l dry l i v e r . These r e s u l t s g e n e r a l l y agree with those p r e v i o u s l y reported, e s p e c i a l l y i f c o n s i d e r a t i o n i s given t o the s e v e r i t y of vitamin A r e s t r i c t i o n and the age of the b i r d s . The report by Janson and H a r r i I I (1974) t h a t a decreased glycogen d e p o s i t i o n may be associated with an acute d e f i c i e n c y in r a t s supports Johnson and Wolf (1960) who found e s s e n t i a l l y no glycogen d e p o s i t i o n in a v i t a m i n o s i s A. Nockels and P h i l l i p s (1971 a + b) found higher l i v e r glycogen values f o r m i l d l y d e f i c i e n t chickens but l a t e r reported a decrease i f l i v e r glycogen was expressed on a percent basis (Nockels e t a I. 1973). Perek and Kendler (1969) a l s o reported t h a t l i v e r glycogen decreased in v vitamin A d e f i c i e n c y . In Experiment 3, both c o n t r o l and m i l d l y d e f i c i e n t b i r d s i n d i c a t e d 48 an age-dependent decrease in percent l i v e r glycogen f o r b i r d s 9 through 12 weeks o l d . This i s not in accord with the increase observed by Perek and Kendler (1969), but t h e i r f i n d i n g s were obtained with 19 and 33 day o l d ch i c k s . Vitamin A stores in l i v e r are d e f i n i t e l y a v a i l a b l e when urgentl y needed and have been shown to be a r e l i a b l e c r i t e r i o n f o r determining the s t a b i l i t y , a v a i l a b i l i t y and u t i l i z a t i o n of, d i e t a r y vitamin A (Harms e t aj_. 1955). Vitamin A d e f i c i e n t c o c k e r e l s showed a marked reduction in t h e i r l i v e r s tores though the f a c t t h a t the vitamin A determinations were based on pooled samples precludes the use of s t a t i s t i c a l a n a l y s i s . Although a f a i r l y rapid response was anticipated,-the extremely low l e v e l s of l i v e r vitamin A encountered in the f i r s t two weeks of d e f i c i e n c y in Experiment 2 are p u z z l i n g . Perhaps the s t r e s s of i n f e c t i o n was s u f f i c i e n t t o reduce these l e v e l s p r i o r to treatment a I l o c a t i o n . The e f f e c t of r e p l e t i o n was a dramatic one and the gradual increase in l i v e r vitamin A s t o r e s was expected. Vitamin A d e f i c i e n c y does not s i g n i f i c a n t l y i n f l u e n c e the ATP content of P. major muscle but does e x e r t an e f f e c t on i t s glycogen l e v e l , an e f f e c t t h a t i s perhaps best demonstrated in Experiment 3 where the r e s u l t s are less confounded by e i t h e r an i n f e c t i o n or a recent v a c c i n a t i o n . Consistent with i t s e f f e c t on hepatic carbohydrate metabolism, mild hypovitaminosls A induces glycogen d e p o s i t i o n while a severe d e f i c i e n c y tends to lower these elevated l e v e l s . Although increased glycogen l e v e l s were noted f o r the m i l d l y d e f i c i e n t b i r d s the d i f f e r e n c e s from the c o n t r o l values were n o n s i g n i f i c a n t , p o s s i b l y due t o the smaller number of b i r d s included in the m i l d l y d e f i c i e n t group and/or to the s i g n i f i c a n t trend of i n c r e a s i n g glycogen content with i n c r e a s i n g 49 age e x h i b i t e d by c o n t r o l b i r d s . This trend was not evident f o r the c o n t r o l group in Experiment 2 where sampling began when the b i r d s were 6 weeks o l d compared to the 9 week-old b i r d s i n i t i a l l y sampled in Experiment 3. These r e s u l t s are in accord with Nockels and P h i l l i p s (1971a) who reported a n o n s i g n i f i c a n t trend of i n c r e a s i n g muscle glycogen with i n c r e a s i n g vitamin A d e f i c i e n c y f o r m i l d l y d e f i c i e n t chickens at 8 and 16 weeks of age. The age-dependent increase noted f o r c o n t r o l s supports Rosebrough and Begin (1975) who found t h a t age s i g n i f i c a n t l y influenced muscle glycogen content in both carbohydrate and f a t d i e t s . The elevated glycogen l e v e l s in the f i r s t two weeks of d e f i c i e n c y in Experiment 2 may r e f l e c t the s t r e s s of Newcastle disease while the s l i g h t drop in the t h i r d week may be due t o the a d d i t i o n a l s t r e s s of the v a c c i n a t i o n procedure. The P. major samples excised from treatment b i r d s e x h i b i t e d a normal pattern of postmortem isometric tension development and d e c l i n e but g e n e r a l l y required longer to develop maximum tension and, in the l a t e r stages of d e f i -c i e n c y , i n d i c a t e d greater tension development than corresponding c o n t r o l samples. The p r e v i o u s l y observed delay In response t o the refeeding of avvitamin A adequate r a t i o n i s again evident - both isometric tension parameters are s i g n i f i c a n t l y higher f o r t r e a t e d b i r d s in the f i r s t week of r e p l e t i o n but are s i m i l a r f o r the c o n t r o l and t r e a t e d b i r d s of the second week. There are several p o s s i b l e explanations f o r t h i s e f f e c t of vitamin A on isometric tension development. The f i r s t would consider the e f f e c t of vitamin A d e f i c i e n c y on the s t r u c t u r a l and c e l l u l a r i n t e g r i t y of the muscle samples. This cannot be completely disregarded as h i s t o l o g i c a l examinations were not performed on any of the samples; however, as(1) a normal pattern of 50 development and d e c l i n e was shown by the treatment b i r d s and (2) some of the d e f i c i e n t b i r d s were capable of developing s i g n i f i c a n t l y greater tension than c o n t r o l s , t h i s p o s s i b i l i t y may not deserve great emphasis. A second explanation considers the e f f e c t of a v i t a m i n o s i s A on the a v a i l a b i l i t y and/or concentration of the major metabolites which have a r o l e in postmortem shortening: ATP and glycogen. There are no reports which d i r e c t l y i n d i c a t e t h a t muscle ATP i s not r e a d i l y a v a i l a b l e f o r c o n t r a c t i o n but Nockels and P h i l l i p s (1971a) found t h a t vitamin A d e f i c i e n c y impared l a c t i c a c i d syn-t h e s i s from glycogen in white muscle. If t h i s impairment i s i n d i c a t i v e of an o v e r a l l slower ra t e of anaerobic g l y c o l y s i s - an e s s e n t i a l , though i n e f f i c i e n t source of new ATP postmortem - an extension in the time required to reach maximum isometric tension would be expected. On the other hand, i f the rate of anaerobic g l y c o l y s i s i s not markedly a f f e c t e d by a vitamin A d e f i c i e n c y , actual metabolite concentrations must be examined. Though s l i g h t l y elevated ATP l e v e l s were observed (Experiment 2), t h i s e f f e c t was not as c o n s i s t e n t as t h a t observed f o r muscle glycogen content where mild hypovitaminosis A induced glycogen d e p o s i t i o n . Bate-Smith and Bendall (1949) described one type of r i g o r mortis t h a t was c h a r a c t e r i z e d by a long delay t o i t s onset and occurred in w e l l - f e d animals whose muscles had a high level of glycogen. It i s not unreasonable to expect an increase in the time t o maximum tension where elevated glycogen l e v e l s occur. The i n t e r r e I a t e d n e s s of isometric t e n s i o n parameters with metabolite concentrations can be seen when the c o r r e l a t i o n c o e f f i c i e n t s determined f o r t h i s study are examined. For c o n t r o l b i r d s (Experiment 2 ) , a s i g n i f i c a n t p o s i t i v e a s s o c i a t i o n e x i s t s between the time t o maximum tension and ATP; a 51 f i n d i n g in accord with Vanderstoep and Richards (1974) who reported t h a t approximately f i f t y percent of the observed v a r i a t i o n s in the timevto maximum tension could be explained by d i f f e r e n c e s in the i n i t i a l ATP content of turkey p e c t o r a I i s major. This a s s o c i a t i o n was a l s o found f o r the d e f i c i e n t b i r d s of Experiment 2, together with a s i g n i f i c a n t dependence on muscle glycogen content. For the t r e a t e d b i r d s of Experiment 3, only the glycogen content was s i g n i f i c a n t l y c o r r e l a t e d with the time t o maximum t e n s i o n . The e f f e c t of vitamin A d e f i c i e n c y on P. major metabolite concentrations and the i n f l u e n c e of these changes on the parameters of i s o m e t r i c tension development should be evident in shear values. A v i t a m i n o s i s A does not appear t o s u f f i c i e n t l y a l t e r any of the f a c t o r s c o n t r i b u t i n g t o shear value u n t i l the l a t e r stages of d e f i c i e n c y , when the t r e a t e d b i r d s were found t o be s i g n i f i c a n t l y tougher than c o n t r o l s . This increased shear value may be a t t r i b u t e d t o e i t h e r the length of the aging period (as the t r e a t e d b i r d s tend to r e q u i r e longer to reach maximum tension) or an increased degree of m y o f i b r i l l a r c o n t r a c t i o n . The l a t t e r seems the most l i k e l y p o s s i b i l i t y . The maximum tension values f o r the d e f i c i e n t b i r d s of the f i f t h d e p l e t i o n weekend the m i l d l y d e f i c i e n t b i r d s in the f i r s t week of r e p l e t i o n were s i g n i f i c a n t l y greater than c o n t r o l values, and correspondingly greater shear values were observed f o r t r e a t e d b i r d s . Nakamura at aj_. (1975) reported t h a t a very high c o r r e l a t i o n between shear value and age could be found in chickens, and Marsh (1977) l a t e r sug-gested t h a t t h i s age r e l a t e d tenderness r e f l e c t e d an increase in the thermal r e s i s t a n c e of the intermolecular c r o s s l i n k s of the muscle c o l l a g e n . These changes in the c o l l a g e n molecule may have c o n t r i b u t e d somewhat to the age-dependent increase in shear value noted in Experiment 2 but a more l i k e l y 52 explanation considers the developmental stage: the b i r d s are a c t i v e l y growing between 6 and 10 weeks of age and the o v e r a l l increase in muscle mass may be the f a c t o r p r i m a r i l y responsible f o r the tr e n d . The nature of the r e l a t i o n s h i p s t h a t e x i s t between metabolite concentrations, i s o m e t r i c tension parameters and shear value i s subject t o wide v a r i a t i o n . Busch et aj_. (1967) reported t h a t no d i r e c t r e l a t i o n s h i p , e x i s t e d between ATP and shear r e s i s t a n c e . Lee et_ aj_. (1976) found t h a t i n i t i a l glycogen l e v e l s and the postmortem g l y c o l y s i s r a t e were s i g n i f i c a n t l y c o r r e l a t e d with the shear value of ground muscle. Other workers have i n d i c a t e d a s i m i l a r a s s o c i a t i o n between shear and the rate of postmortem g l y c o l y s i s (deFremery, 1966; Khan and Kim, 1975). Khan (1974) reported t h a t the u l t i m a t e shear force appears t o be d i r e c t l y p r o p o r t i o n a l t o the maximum isometric t e n s i o n developed, whereas Wood (1973) found t h a t shear had a p o s i t i v e r e l a t i o n s h i p with both tension and time. The r e s u l t s of t h i s study i n d i c a t e s i g n i f i c a n t p o s i t i v e a s s o c i a t i o n s between the time t o maximum tension with ATP and/or glycogen content. However, the negative c o r r e l a t i o n s found f o r the maximum tension and shear and f o r ATP and shear r e q u i r e f u r t h e r study. 53 SUMMARY AND CONCLUSIONS Avitaminosis A had l i t t l e or no e f f e c t on e i t h e r body weight gain or l i v e r weight during i t s e a r l y stages but depressed both as the d e f i c i e n c y progressed. A s i g n i f i c a n t decrease in feed e f f i c i e n c y was a l s o noted in the l a t e r d e f i c i e n c y stages. Vitamin A d e f i c i e n c y did express an e f f e c t on both hepatic and muscle carbohydrate metabolism and the natu're of the response appears r e l a t e d to the progress of d e f i c i e n c y . M i l d hypovitaminosis A induced an increase in glycogen de p o s i t i o n whereas a severe d e f i c i e n c y led to a reduction of these elevated s t o r e s . The a b i l i t y of P. major s t r i p s t o develop is o m e t r i c t e nsion postmortem was not influenced by d i e t a r y vitamin A though some changes in the measured parameters were noted. The P. major from cockerels in the l a t e r stages of d e f i c i e n c y required longer to reach maximum tension and developed s i g n i f i c a n t l y greater maximum tension than those from c o n t r o l s . The extended times r e f l e c t e d elevated muscle glycogen content. A s i g n i f i c a n t increase in shear value was observed when the increase in maximum tension occurred. Although there was a delayed response to the refeeding of a vitamin A adequate r a t i o n , vitamin A r e p l e t i o n a l s o influenced the studied parameters. Muscle glycogen content, isometric t e nsion parameters and shear r e s i s t a n c e returned to values s i m i l a r to those of c o n t r o l s w i t h i n a two week period. On the^ basis of t h i s data i t can be concluded that the n u t r i t i o n a l s t a t u s of vitamin A influences both the carbohydrate metabolism and the isome t r i c tension parameters of muscle t i s s u e , with a concomitant d e l e t e r i o u s e f f e c t on the ul t i m a t e muscle tenderness. 54 LITERATURE CITED Bate-Smith, E.C. 1948. The physiology and chemistry of r i g o r m o r t i s , with s p e c i a l reference t o the aging of beef. Adv. Food Res. 1: 1. Bate-Smith, E.C. and B e n d a l l , J.R. 1949. Factors determining the time course of r i g o r mortis. J . Physiol.'110:"47. B e n d a l l , J.R. 1973. Postmortem changes in muscle. In "The S t r u c t u r e and Function of Muscle," 2nd ed., V o l . II ed. G.H. Bourne. Academic Press, New York. Borchert, L.L. and B r i s k e y , E.J. 1965. P r o t e i n s o l u b i l i t y and a s s o c i a t e d p r o p e r t i e s of porcine muscle as influenced by p a r t i a l f r e e z i n g with l i q u i d n i t r o g e n . J . Food S c i . 30: 138. B r u c k e n t a l , I., A s c a r e l l i , I. and Bondi, A. 1974. E f f e c t of vitamin A d e f i c i e n c y on p r o t e i n catabolism in c h i c k s . Br. J . Nutr. 31: 1. Busch, W.A., P a r r i s h , F.C. J r . and G o l l , D.E. 1967. Molecular p r o p e r t i e s of postmortem muscle. 4. E f f e c t of temperature on adenosine triphosphate degradation, isometric tension parameters and shear r e s i s t a n c e of bovine muscle. J . Food S c i . 32: 390. Busch, W.A., G o l l , D.E. and P a r r i s h , F.C. J r . 1972. Molecular p r o p e r t i e s of postmortem muscle. Isometric tension development and d e c l i n e in bovine, porcine and r a b b i t muscle. J . Food S c i . 37: 289. Cassens, R.G. and Newbold, R.P. 1967. E f f e c t of temperature on the time course of r i g o r mortis in ox muscle. J . Food S c i . 32: 269. Cassens, R.G. 1977. Muscle biochemistry: the importance of myofiber type. Food Technology 31: 76. Cohen, C. 1975. The p r o t e i n switch of muscle c o n t r a c t i o n . S c i e n t i f i c Amer-ican. Nov. 1975: 36. Dalrymple, R.H. And Hamm, R. 1973. A method f o r the e x t r a c t i o n of glycogen and metabolites from a s i n g l e muscle sample. J . Fd. Technology 8: 439. deFremery, D. and P o o l , M.F. 1960. Biochemistry of chicken muscle as r e l a t e d t o r i g o r mortis and t e n d e r i z a t i o n . Food Research 25: 73. deFremery, D. 1966. R e l a t i o n s h i p between chemical p r o p e r t i e s and tenderness of p o u l t r y muscle. J . Agr. Food Chem. 14: 214. Dileepan, K.N., Ramachandran, C.K., Singh, V.N. and Venkitasubramanian, T.A. 1974. E f f e c t of excess and d e f i c i e n c y of vitamin A on adenyl c y c l a s e and c y c l i c AMP phosphodiesterase of r a t l i v e r . Nutr. Rep. I n t l . 10 (5): 327. 55 Dorr, P. and B a l l o u n , S.L. 1976. E f f e c t of d i e t a r y vitamin A a s c o r b i c a c i d and t h e i r i n t e r a c t i o n on turkey bone m i n e r a l i s a t i o n . Br. P o u l t . S c i . 17: 581. Dugan, R.E., F r i g e r i o , N.A. and S i e b e r t , J.M. 1964. C o l o r i m e t r i c determination of vitamin A and i t s d e r i v a t i v e s with t r i f l o u r o a c e t i c a c i d . A n a l y t i c a l Chem. 36: 114. Gomori, G. 1955. Preparation of b u f f e r s f o r use in enzyme s t u d i e s . Methods in Enzymology 1: 138. Harms,. R.H., Reid, B.L. and Couch, J.R. 1955. Storage of vitamin A in chicken l i v e r as c r i t e r i a of s t a b i l i t y , a v a i l a b i l i t y and d i e t a r y l e v e l . P o u l t r y Science 34: 1125. H e r r i n g , H.K., Cassens, R.G. and B r i s k e y , E.J. 1965. Sarcomere length of f r e e and r e s t r a i n e d bovine muscles at low temperature as r e l a t e d t o tenderness. J . Science Food A g r i c . 16: 379. Howard, R.D. and Judge, M.D. 1968. Comparison of sarcomere length t o other p r e d i c t o r s of beef tenderness. J . Food S c i . 33: 456. Janson, M. and H a r r i l l , I. 1974. E f f e c t of vitamin A on a d r e c o r t i c a l a c t i v i t y of r a t s fed s e l e c t e d amino a c i d s . Nutr. Rep. I n t l . 10 ( 3 ) : 121. Johnson, B.C. and Wolf, G. 1960. The f u n c t i o n of vitamin A in carbohydrate metabolism; i t s r o l e in a d r e n o c o r t i c o f d production. V i t s . Hormones 18: 457. Jungk, R.A., Snyder, H.E., G o l l , D.E. and McConnell, K.G. 1967. Isometric tension changes and shortening in muscle s t r i p s during postmortem aging. J . Food S c i . 32: 158. Jungk, R.A . y Snyder, H.E., G o l l , . D.E. and McConnell, K.G. 1.974. Isometric tens Ion.changes and shortening in muscle s t r i p s during postmortem aging. J . Food S c i . 39: 158. Jungk, R.A. and Marion, W.W. 1970. Postmortem isometric tensioncchanges and shortening in turkey muscle s t r i p s held at various temperatures. J . Food S c i . 35: 143. Khan, A.W. and Kim, Y.K. 1975. E f f e c t of calcium on isometric t e n s i o n , g l y c o l y s i s and tenderness of p o u l t r y breast meat. J . Food S c i . 40: 1119. Khan, A.W. 1974. R e l a t i o n between iso m e t r i c t e n s i o n , postmortem pH d e c l i n e and tenderness of p o u l t r y breast meat. J . Food S c i . 39: 393. Krause, R.F., Beamer, K.C., McCormick, A.M., Canterbury, R.J. and T r y f i a t e s , G.P. 1975. The e f f e c t of r e t i n o l and r e t i n o i c a c i d on p h y s i o l o g i c a l and biochemical changes in r e t i n o I - d e f i c i e n t r a t s . Br. J . Nutr. 33: 73. 56 Lamprecht, W. and T rau tcho ld , I. 1963. Adenosine 5 of t r i pho spha te . Dete r -minat ion with HK and G-6-PDH in Methods of Enzymatic A n a l y s i s . Bergmeyer, H.U. (ed.) 543-551 Academic Press N.Y. 1965. Lee, Y .B. , Hargus, G.L., Hagberg, E.C. and Forsythe, R.H. 1976. E f f e c t of antemortem enviromnentaI temperatures on postmortem g l y c o l y s i s and t e n -derness in exc i sed b r o i l e r breast muscle. J . Food S c i . 41: 1466. Lopez, G.A., P h i l l i p s , R.W. and Nockel s , C.F. 1973. Body water k i n e t i c s in v i tamin A d e f i c i e n t ch i ckens . Proc. Soc. Exp. B i o l . Med. 144: 54. Mahant, L. and Eaton, H.D. 1976. E f f e c t of ch ron i c hypov i taminos i s A on water metabolism in the weanl ing r a t . J . N u t r i t i o n 106: 1817. Mannherz, H.G. and Goody,. R . S . )1976 . P r o t e i n s of c o n t r a c t i l e systems. Ann. Review Biochem. V o l . 45: 427. Mar ion, W.W. 1967. Meat tenderness in the av ian spec i e s . Wor ld ' s Pou l t r y S c i . J . 23: 6. Mar ion, W.W. 1971. Turkey tenderness and a s soc ia ted physiochemicaI parameters. Feed s tu f f s , A p r i l 3, p. 24. Marsh, B.B. and Leet, N.G. 1966. Stud ies in meat tenderness. 3. The e f f e c t s of c o l d shor ten ing on tenderness. J . Food S c i . 31: 450. Marsh, B.§. 1977. The bas i s of tenderness in muscle foods. J . Food S c i . 42: 295. McCollum, E.V. and Dav is , M. 1913. Necess i ty of c e r t a i n l i p i n s in the d i e t dur ing growth. J . B i o l . Chem. 15: 167. Murray, J.M. and Weber, A. 1974. The coopera t i ve a c t i on of muscle p r o t i e n s . S c i e n t i f i c American Feb. 1974: 58. Nakamura, R., Sekoguchi, S. and Sato, Y. 1975. The c o n t r i b u t i o n of i n t r a -muscular co l l a gen to the tenderness of meat from ch ickens with d i f f e r e n t ages. Pou l t r y Science 54: 1604. Newbold, R.P. and H a r r i s , P.V. 1972. The e f f e c t of p r e r i g o r changes on meat tenderness. A review.' J . Food S c i . 37: 337. Nockels , C.F. and K ienho l z , E.W. 1967. Inf luence of v i t amin A d e f i c i e n c y on t e s t e s , bursa f a b r i c i u s , adrenal and hematocr i t in c o c k e r e l s . J . Nutr . 92: 384. Nockel s , C.F. and P h i l l i p s , R.W. 1971a. Inf luence of v i t amin A d e f i c i e n c y on t i s s u e glycogen metabolism in growing c h i c k e n s . " P ou l . S c i . 50: 174. Nockels , C.F. and P h i l l i p s , R.W. 1971b. Indluence of d i e t a r y v i tamin A leve l on ch icken l i v e r g lycogen. Pou l t r y Sc ience 50: 766. 57 Nockels, C.F.,.Lopez, G.A., and P h i l l i p s , R.W. 1973. Influence of vitamins A and C on c o r t i c o s t e r o n e and carbohydrate metabolism in chickens. P o u l t r y Science 52: 1261. Osborne, T.B. and Mendel I, L.B. 1913. The r e l a t i o n of growth to the chemical, c o n s t i t u t i o n of the d i e t . J . B i o l . Chem. 15: 311. Perek, M. and Kendler, J . 1969. The e f f e c t of as c o r b i c a c i d on the carbohydrate metabolism of vitamin A d e f i c i e n t c h i c k s . P o u l t r y Science 48: 1101. P f l e i d e r e r , G. 1963. Glycogen. Determination as D-glucose with HK, PK and LDH in Methods of Enzymatic A n a l y s i s . Bergmeyer, H.U. (ed.) 59-62 Academic Press, N.Y. 1965. Rosebrough, R.W. and Begin, J . J . 1975. The e f f e c t of non-protein energy source and age on the blood glucose lev e l and the muscle glycogen content of young c h i c k s . P o u l t r y Science 54: 1327. Schmidt, G.R., Cassens, R.G. and B r i s k e y , E.J. 1970a. Changes in te n s i o n and c e r t a i n metabolites during the development of r i g o r mortis in se l e c t e d red and white s k e l e t a l muscles. J . Food S c i . 35: 571. Schmidt, G.R., Cassens, R.G. and Br i s k e y , E.J. 1970b. R e l a t i o n s h i p of calcium uptake by the sarcoplasmic r e t i c u l u m to tension development and r i g o r mortis in s t r i a t e d muscle. J . Food S c i . 35: 574. Sco t t , M.L., Nesheim, M.C. and Young, R.J. 1969. N u t r i t i o n of the chicken. M.L. Scott and Associates Ithaca, N.Y. Singh, S.P. and Donovan, G.A. 1973. A r e l a t i o n s h i p between C o c c i d i o s i s and d i e t a r y vitamin A l e v e l s in chickens. P o u l t r y Science 52: 1295. S t e e l , R.G.D. and T o r r i e , J.H. 1960. P r i n c i p l e s and Procedures in S t a t i s t i c s McGraw-Hil, Mew York. Stoewsand, G.S. and S c o t t , M.L. 1964. E f f e c t of s t r e s s from high p r o t e i n d i e t s on vitamin A metabolism in c h i c k s . J . Nutr. 82: 188. Vanderstoep, J . and Richards, J.F. 1974. Postmortem g l y c o l y t i c and phys i c a l changes in turkey breast muscle. Can. Inst. Food S c i . Techno I. J . 7(2): 120. Washko, M.E. and Rice, E.W. 1961. Determination of glucose by an improved " g l u c o s t a t " procedure. C l i n . Chem. 7: 542. Wood, D.F. 1973. Some postmortem aspects of b r o i l e r breast muscle. PhD. t h e s i s . U n i v e r s i t y of B r i t i s h Columbia. Wood, D.F. And Richards, J.F. 1974. Isometric tension s t u d i e s on chicken Pectoral i s major muscle. J . Food S c i . 39: 525. 

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