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Post-mortem glycolytic and physical changes in turkey breast muscle Vanderstoep, John 1971

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by JOHN VANDERSTOEP B.S.A., University of British Columbia, 1966 M.S.A., University of British Columbia, 1968 A THESIS SUBMITTED IN PARTIAL FULFILMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY in the Department of Food Science We accept this thesis as conforming to the required standard. THE UNIVERSITY OF BRITISH COLUMBIA Ap r i l , 1971 In p resent ing t h i s t h e s i s in p a r t i a l f u l f i l m e n t o f the requirements f o r an advanced degree at the U n i v e r s i t y of B r i t i s h Columbia, I agree that the L i b r a r y s h a l l make i t f r e e l y a v a i l a b l e f o r reference and study . I f u r t h e r agree t h a t permiss ion fo r e x t e n s i v e copying o f t h i s t h e s i s f o r s c h o l a r l y purposes may be granted by the Head of my Department or by h i s r e p r e s e n t a t i v e s . It i s understood that copying or p u b l i c a t i o n o f t h i s t h e s i s f o r f i n a n c i a l ga in s h a l l not be a l lowed without my w r i t t e n p e r m i s s i o n . John Vanderstoep. Department of Food Science The U n i v e r s i t y of B r i t i s h Columbia Vancouver 8, Canada Date April 27, 1971. The c o n c e n t r a t i o n of g l y c o l y t i c i n t e r m e d i a t e s and c o - f a c t o r s i n and pH v a l u e s of P. s u p e r f i c l a l i s muscles from each of f i v e 15 week-old and f i v e 25 week-old White Cannon torn turkeys was measured at v a r y i n g times between 0 and 180 min. post-mortem. D i f f e r e n t r a t e s of post-mortem g l y c o l y s i s were e v i -dent among b i r d s , independent of age. On the b a s i s of ATP c a t a b o l i s m , pH and l a c t i c a c i d accumulation, two groups c a t e -g o r i z e d as " f a s t - " and " s l o w - g l y c o l y z i n g " were e v i d e n t . The d i f f e r e n t r a t e s of g l y c o l y s i s c o u l d not be e x p l a i n e d by q u a l i -t a t i v e or q u a n t i t a t i v e d i f f e r e n c e s i n c o n t r o l of the g l y c o l y t i c f l u x . The p a t t e r n s of change i n c o n c e n t r a t i o n of i n t e r -mediates and c o - f a c t o r s expressed as mass a c t i o n r a t i o s suggest-ed t h a t r e g a r d l e s s of g l y c o l y t i c r a t e , post-mortem g l y c o l y s i s i n turkey b r e a s t muscle i s s u s c e p t i b l e to c o n t r o l a t the r e -a c t i o n s c a t a l y z e d by hexokinase, phosphofructo k i n a s e , a l d o -l a s e and t r i o s e p h o s p h a t e isomerase, g l y c e r a l d e h y d e phosphate dehydrogenase and phosphoglycerokinase and pyruvate k i n a s e . P. s u p e r f i c i a l i s muscles from s i x 19 and s i x 27 week-o l d White Cannon torn t u r k e y s were analyzed f o r ATP c o n c e n t r a t i o n a t "0" and "60" min. post-mortem and muscle pH was determined d u r i n g a t h r e e hour post-mortem p e r i o d . The time r e q u i r e d f o r e x c i s e d muscle s t r i p s t o achieve maximum c o n t r a c t i o n was de-termined by p e r i o d i c measurement of s t r i p l e n g t h . A n a l y s i s of the data i n d i c a t e d a r e l a t i o n s h i p between r a t e of ATP c a t a b o l i s m and time to maximum c o n t r a c t i o n . "Slow-" and " f a s t - g l y c o l y z i n g " groups were evident and were indepen-dent of age. The " s l o w - g l y c o l y z i n g " group had a h i g h e r i n i t i a l ATP c o n c e n t r a t i o n , a l a r g e r p r o p o r t i o n of i n i t i a l ATP remain-i n g a t 60 min. and r e q u i r e d a l o n g e r time f o r the muscle s t r i p s t o a chieve maximum c o n t r a c t i o n . A b s t r a c t i i i L i s t of Tables v i i i L i s t of F i g u r e s x Acknowledgements x i i INTRODUCTION 1 LITERATURE REVIEW 2 General Muscle Metabolism 2 Post-mortem Metabolism 3 Post-mortem Metabolism and Meat 4 Pale S o f t Exudative Pork 4 Dark C u t t i n g Beef 6 C h a l k i n e s s i n H a l i b u t 6 P o u l t r y 7 P h y s i c a l Changes Post-mortem 11 P h y s i c a l Measurements 13 MATERIALS AND METHODS 15 Experiment I 15 Muscle Samples 15 pH 16 P r e p a r a t i o n of Muscle E x t r a c t s 16 A n a l y t i c a l Methods 18 Chemicals 19 Experiment III 20 Experiment IV 21 RESULTS AND DISCUSSION 23 Experiments I to III 23 pH 23 Glycolytic Intermediates and Co-factors 26 Intermediates of 15 Week-old Birds 26 Co-factors of 15 Week-old Birds 29 Intermediates of 25 Week-old Birds 32 Co-factors of 25 Week-old Birds 33 Comparison of Intermediate and Co-factors for 15 and 25 Week-old Birds 40 Possible Sites of Post-mortem Glycolytic Control 43 ATP Metabolism 47 Lactic Acid and pH 48 pH Pattern of Group I and Group II 50 Glycolytic Intermediates and Co-factors of Groups I and II 51 Lactic Acid and pH for Group I and Group II 65 Possible Sites of Post-mortem Glycolytic Control for Group I and Group II 66 Experiment IV 68 pH 68 ATP 69 Rigor Mortis Measurement 70 Rigor Mortis vs. ATP 75 Page Regrouping of Data on B a s i s of ATP Disappearance Rates 75 SUMMARY AND CONCLUSIONS 80 LITERATURE CITED 82 APPENDIX A APPENDIX B Table Page I pH of P. superficialis at Varying Times Post-mortem for 15 and 25 Week-old Turkeys 24 II Concentration of the Glycolytic Intermediates and Co-factors in P. superficialis Muscle at Varying Times Post-mortem tor 15 Week-old Turkeys 27 III Concentration of the Glycolytic Intermediates and Co-factors in P. superficialis Muscle at Varying Times Post-mortem for 25 Week-old Turkeys. 30 IV Average Coefficients of Variability Associated With the Plots of the Mean Concentrations of Intermediates and Co-factors Over Time Post-mortem. 41 V Mass Action Ratios of the Glycolytic Reactions 44 VI Mass Action Ratios Calculated from "0" Minute Data on Glycolytic Intermediates and Co-factors in Muscle of 15 and 25 Week-old Birds 45 VII ATP Concentration as a Percentage of I n i t i a l ATP Concentration 50 VIII Comparison of pH Values at Varying Times Post-mortem for Group I and Group II Turkeys 51 IX Concentration of the Glycolytic Intermediates and Co-factors in P. superficialis Muscle at Varying Times Post-mortem for Group I Turkeys 52 X Concentration of the Glycolytic Intermediates and Co-factors in P. superficialis Muscle at Varying Times Post-mortem for Group II Turkeys 55 XI Mass Action Ratios Calculated from "0" Minutes Data on Glycolytic Intermediates and Co-factors in Muscles of Group I and II Turkeys 67 XII pH of P. superficialis Muscle at Varying Times Post-mortem for iy and 27 Week-old Turkeys (Exp. IV) 69 XIII Comparison of ATP Concentration in P. super-f i c i a l i s Muscles at "0" and "60" Minutes Post-mortem for 19 and 27 Week-old Turkeys (Exp. IV) 70 XIV Times to Maximum Contraction for Individual 19 and 27 Week-old Birds (Exp. IV) 74 XV Relationship Between ATP Concentration and Time to Maximum Muscle Contraction (Exp. IV) 76 Figure Page 1 Comparisons of concentrations of some gly-colytic intermediates in P. superficialis muscles from 15 week-old and~~Z5 week-old turkeys. 34 2 Comparisons of concentrations of some gly-colytic intermediates in P. superficialis muscles from 15 week-old and 25 week-old turkeys. 35 3 Comparisons of concentrations of some gly-colytic intermediates in P. superficialis muscles from 15 week-old and 25 week-old turkeys. 36 4 Comparisons of concentrations of some gly-colytic intermediates in and pH values of P. superficialis muscles from 15 week-old and 25 week-old turkeys. 37 5 Comparisons of concentrations of some gly-colytic co-factors in P. superficialis muscles from 15 week-oTd and 25 week-old turkeys. 38 6 Comparisons of concentrations of some gly-colytic co-factors in P. superficialis muscle from 15 week-olH and 25 week-old turkeys. 39 7 Comparisons of concentrations of some gly-colytic intermediates in P. superficialis muscles in Group I turkeys and Group II turkeys. 57 8 Comparisons of concentrations of some gly-colytic intermediates in P. superficialis muscles in Group I turkeys and Group II turkeys. 58 Comparisons of c o n c e n t r a t i o n s of some g l y -c o l y t i c i n t e r m e d i a t e s i n P. s u p e r f i c i a l i s muscles i n Group I turkey's and Group II t u r k e y s . Comparisons of c o n c e n t r a t i o n s of some g l y -c o l y t i c i n t e r m e d i a t e s i n and pH v a l u e s of P. s u p e r f i c i a l i s muscles i n Group I turkeys and Group II t u r k e y s . Comparisons of c o n c e n t r a t i o n s of some g l y -c o l y t i c c o - f a c t o r s i n P. s u p e r f i c i a l i s muscles i n Group I turlteys and Group I I t u r k e y s . Comparisons of c o n c e n t r a t i o n s o f some g l y -c o l y t i c c o - f a c t o r s i n P. s u p e r f i c i a l i s muscles i n Group I turk"eys and Group I I t u r k e y s . T y p i c a l c o n t r a c t i o n p a t t e r n s of P. super-f i c i a l i s muscle s t r i p . P l o t of maximum c o n t r a c t i o n time v s . 7,-ATP (ATP cone, at 60 min. as a percent of ATP cone. a t 0 min.). The author wishes to express his sincere appreciation to his advisor, Dr. J .F. Richards, Associate Professor, Depart-ment of Food Science, for his suggestions, help and encourage-ment throughout the course of this study. He is also thankful to the members of his graduate committee: Dr. S. Nakai, Department of Food Science Dr. W.D. Powrie, Department of Food Science Dr. J .F. Phillips, Department of Zoology Dr. N. Tomlinson, Fisheries Research Board for their encouragement and continued interest in the research and for the review of this thesis. The author is grateful to Dr. C.W. Roberts, Depart-ment of Poultry Science, for the use of the poultry farm fac i l i t ies , and to Mr. W. Gleave, Department of Agricultural Engineering, for construction of the rigor measuring device. The monetary support of the National Research Council and the H.R. MacMillan Foundation through post-graduate scholar-ships is gratefully acknowledged. — Meat forms an important and substantial part of the human diet in the western world. The 1966 Canadian census (Canada Yearbook, 1967) revealed that the per capita disappear-ance of a l l red meats in 1965 was 146.3 pounds (eviscerated weight). The total poultry consumption in the same year was 36.0 pounds per capita. Of this 9.5 pounds was turkey. The 1970 Who's Who of the Poultry Industry in Canada reported a farm placement in 1969 of 9,774,025 turkey poults for broiler weights and 8,205,635 turkey poults for heavy weights. In the same year 9,188,000 turkeys of 10 pounds and under, 3,217,000 turkeys of over 10 pounds but under 16 pounds and 3,702,000 turkeys of 16 pounds and over were slaughtered. The important factors which should be considered in the eating quality of meat are tenderness, flavour, juiciness and aroma. However, several consumer studies have shown that tenderness i s one of the most important palatability factors in the acceptance of meat. The quality of meat that is consumed is influenced by ante-mortem and post-mortem factors operative during the con-version of muscle to meat. Briskey (1964), Lister (1970) and Khan et a l . (1970) among others, have shown that the metabo-lism of muscle both ante- and post-mortem, is a major factor influencing the quality attributes of the subsequent meat. This thesis describes a study of post-mortem glycogen metabolism and rigor development in muscles of turkeys of two ages. General Muscle Metabolism Many research papers have been published on the physiology and chemistry of muscle. Bendall (1966), in his mono-graph (1969), describes in detail the organization of muscle into i t s component structural and contractile parts. The process of contraction by means of nerve and muscle action potentials, re-lease of Ca + + from the sarcoplasmic reticulum, activation of the muscle ATP-ase, the subsequent formation of actomyosin, and the functional aspects of contraction and subsequent relaxation is extensively described. Bendall (1966, 1969) has summarized the function of ATP in vivo as the provision of energy for three main uses: to drive the Na+-K+ pump in the plasmalemma; to drive the C a + + pump in the longitudinal elements of the sarcoplasmic reticulum; and as the immediate source of contractile energy. It i s clear that to maintain an appropriate energy supply, extremely efficient resynthetic mechanisms are required for the working muscle. It i s the extent of Interference with the resynthetic mechanism by preslaughter handling and the slaughter processes which are of utmost importance in the conversion of muscle to : meat. Lawrie (1966a) presented an outline of the resynthesis of ATP in muscle. The most immediate source of resynthesis i s considered to be from ADP and creatine phosphate by the soluble s a r c o p l a s m i c enzyme c r e a t i n e k i n a s e . The major source, however, i s the r e s y n t h e s i s from ADP by r e s p i r a t i o n whereby muscle g l y -cogen i s o x i d i z e d to carbon d i o x i d e and watex*. When energy i n excess of the c a p a c i t y of the r e s p i r a t o r y system t o regen e r a t e ATP i s needed, the process of anaerobic g l y c o l y s i s , whereby glycogen i s converted to l a c t i c a c i d , may regenerate ATP, a l -though much l e s s e f f i c i e n t l y than the o x i d a t i v e p r o c e s s . Both Lawrie (1966a) and Kastenschmidt (1970) presented s i m p l i f i e d schemes of muscle metabolism whereby ATP i s r e s y n t h e s i z e d . Post-Mortcm Metabolism Commercial s l a u g h t e r i n g of domestic fowl and l a n d mammals r e s u l t s i n c e s s a t i o n of the oxygen supply t o the muscle and i n the esta b l i s h m e n t of anaerobic g l y c o l y s i s i n the s k e l e t a l muscles. The sequence of b i o - c h e m i c a l r e a c t i o n s by which glycogen i s converted t o l a c t i c a c i d i s e s s e n t i a l l y the same post-mortem as i n v i v o when the oxygen supply may become tempor-a r i l y inadequate f o r the p r o v i s i o n of energy v i a o x i d a t i v e metabolism i n the muscle. Except when i n a n i t i o n or e x c e r c i s e immediately p r e - s l a u g h t e r has a p p r e c i a b l y d i m i n i s h e d the r e s e r v e s of glycogen i n muscle, the post-mortem c o n v e r s i o n of glycogen to l a c t i c a c i d w i l l continue u n t i l a pH i s reached a t which the enzymes e f f e c t i n g the c a t a b o l i s m become i n a c t i v a t e d . The u l t i -mate pH i s g e n e r a l l y about 5.5 which i s near the i s o - e l e c t r i c p o i n t of many muscle p r o t e i n s , i n c l u d i n g those of the s a r c o -plasm and m y o f i b r i l . Lawrie (1966a) has e x t e n s i v e l y reviewed the importance of post-mortem metabolism, and i n p a r t i c u l a r the rate and extent of pH decline, to the production of meat of optimal quality. Both the rate and the extent of the post-mortem pH fa l l are influenced by intrinsic factors such as species, the type of muscle and variability among animals; and by extrinsic factors such as the preslaughter administi-ation of drugs and environmental temperature both ante- and post-mortem. Post-mortem Metabolism and Meat A large body of knowledge about post-mortem metabolism and its relation to meat quality has been acquired from study of a number of species exhibiting anomalous post-mortem changes. Pale Soft Exudative Pork The muscles of living porcine animals are moderately dark in colour, firm in texture and dry in appearance. After exsanguination the physiological and biophysical changes that take place, regulate the differentiation of muscles on the basis of colour, exudation and gross morphology. When these changes are rapid, a condition results which has been called "pale, soft exudative pork" (P.S.E.), "muscle degeneration" (MD) and "white muscle disease", (Briskey, 1964 and Lawrie, 1966a). In his re-view, Briskey (1964) indicates some evidence that structural ab-normalities in P.S.E. and dark, firm dry musculature may be path-ological and dystrophic in nature. However, the major body of evidence suggests this condition is associated with accelerated post-mortem glycolysis and onset of rigor mortis. When these changes are rapid (0.5 to 1.5 hr.) and result in acid conditions at a relatively high temperature, the muscles usually become pale in appearance, soft in texture and extremely exudative (Briskey, 1964 and Briskey el: a l . 1966) . Sayre and co-workers (1963 a,b) were able to show that within the strains available, the muscles of Chester White and Hampshire breeds seldom underwent rapid post-mortem glycolytic changes while this abnormality occured frequently in the muscles of a strain of Poland China animals. Kastenschmidt e_t a l . (1966 and 1968) and Briskey et a l . (1966) used these strain differences to study the rate of post-mortem anaerobic glyco-lysis . Muscles were categorized as "fast-glycolyzing" i f the muscle pH had declined to 5.5 or below at 30 min. post-mortem and "slow glycolyzing" i f the pH was 6.0 or higher at 60 min. post-mortem (Kastenschmidt et a l . 1968). The metabolic inter-mediate patterns of "fast-" and "slow-glycolyzing" muscles were consistent with the concept that phosphorylase is the primary control site of post-mortem glycolysis and that phosphofructo-kinase and pyruvate kinase were also involved. Further work substantiated these findings but studies of reconstituted glycolytic systems in vitro, indicated that i t is unlikely that the control properties of "fast-" and "slow-glycolyzing" systems are grossly different (Kastenschmidt, 1970). The same studies of Kastenschmidt et a l . (1966, 1968) pointed to the possibility that fast-glycolyzing muscles were in an oxygen-deficient state prior to the time of death. Lister et a l . (1970) found that the administration of oxygen or nitrogen immediately before death to anesthetized stress-resistant and stress-susceptible animals resulted in the latter either be-coming anoxic more easily or responding to anoxia to a greater extent than the former. It was found that there was a very rapid production of la c t i c acid during the f i r s t 2 min. after exsanguination in the stress-susceptible muscles and that this could at least partially explain the high levels of l a c t i c acid in fast-glycolyzing muscles. Sybesma et a l . (1968) attempted to prevent the P.S.E. condition by injection of 0£ into the muscle to delay glyco-l y s i s , but found that pre-mortal injection produced gas embo-lism and no clear cut effect on pH and temperature drop. Post-mortal injection did produce a delay in glycolysis but in neither case was there any improvement in subsequent quality. Dark Cutting Beef Dark cutting beef, as the name implies, i s a condition in which muscle surfaces remain purplish, long after the cut surface has been exposed to the atmosphere. Investigation in-to this matter (e.g., Lawrie, 1958; 1966a; 1966b) suggests that in contrast to normal muscle, D.C.B. has an unusually rapid rate of consumption of oxygen, practically no glycogen immedi-ately after slaughter and an ultimate pH considerably higher than the normal 5.4 - 5.6. A survey by Munns and Burrell (1966) indicated that during the years from 1958 to 1961 the average incidence of carcasses yielding D.C.B. in selected Canadian processing plants was eight percent with a range from 3.5 to 12%. Chalkiness in Halibut The lowest post-mortem pH which i s reached i n many species of food f i s h i s about 6.2 to 6.6; but in some species, such as halibut, tuna, mackerel and shark, i t may f a l l to be-tween 5.5 and 6.0 (Buttkus et a l . , 1966). Tomlinson et a l . (1965, 1966) showed that with increasing storage time and de-creasing pH, below about 6.0, the muscle proteins of halibut become more insoluble as the region of the isoelectric zone is reached. As the solubility of the proteins decreased, the appearance of the meat changed from translucent to opaque. A l l fis h with a flesh pH below 6.0 were "chalky", those with a pH above 6.2 nonchalky, while in the pH range between 6.0 and 6.2 intermingling of chalky, borderline chalky, and nonchalky f i s h occurred. Free drip increased continuously with decreasing pH in the range of pH 6.8 to 5.7. As the solubility of the proteins decreased and opa-queness increased, free and cooked drip increased, the nitrogen content of drip increased, and the meat became increasingly tough and dry when cooked, (Buttkus et a l . , 1966). Poultry Poultry meat i s an important part of the human diet. Continued investigation of this meat product i s essential to main-tain and increase i t s acceptance. The post-mortem biophysical and biochemical changes which take place in poultry are not qualitatively different from those of other species used for meat and include the typical stiffening with the onset of rigor mortis, the disappearance of glycogen, ATP and CP; the appearance of ammonia and inosinic acid from the deamination of adenylic acid, and; the accumulation of l a c t i c acid as a result of the anaerobic catabolism of glyco-gen. The accumulation of lactic acid lowers the pK from above 7.0 to ultimate values of 5.7 to 5.9 (de Fremery, 1966a). In contrast to land mammals, post-mortem tenderiza-tion changes are different and poultry requires less time to reach an acceptable level of tenderness (Marion and Goodman, 1967). Numerous factors have been studied to determine their effect on poultry meat tenderness including, breed and strain, sex, ration, grade light vs. dark meat, enzymes, processing methods, and aging time (Marion, 1967). Shrimpton and Miller (1960) found no differences attributable to sex in the tenderness of breast meat of White Rock broilers, but found differences among male Leghorns, White Rock males and females and Brown Leghorns. Goodwin (1966), however, found that when comparing six strains of 26 week-old Broad Breasted Bronze turkeys strain did not have a significant effect on meat tenderness. The administration of enzyme preparations ante-mortem, during aging, just prior to cooking or during rehydra-tion of freeze-dehydrated meat, has been shown to increase ten-derness (Marion, 1967). In studying the chemical properties and their relation to tenderness of poultry muscle, de Fremery (1966b) found that when chickens were subjected to severe mechanical feather-plucking immediately post-mortem, the disappearance of ATP was accelerated and toughness increased. Other pre-rigor treatments such as freezing and thawing, elevated temperatures, excising or cutting the muscle, electron irradiation, and exhaustive electrical stimulation also accelerated ATP and glycogen dis-appearance as well as the onset of rigor mortis, and also i n -duced toughness that was only partially reversed by prolonged aging. Studies supporting the findings of de Fremery above, and others of similar nature have been extensively reviewed by Marion (1967). Heating the muscle as well as beating i t as with a mechanical picker, causes an acceleration of post-mortem gly-colysis (Marion, 1967; de Fremery, 1966a; Sayre, 1970). Injec-tion of sodium pentobarbital and el e c t r i c a l stunning have been shown to retard glycolysis by virtue of reducing death struggle (Sayre, 1970). Dodge and Stadleman (1960) observed that struggle during slaughter did not affect post-mortem tender-ness at 2 or 5 hours post-mortem. However, poultry exhibiting extreme struggling i s generally less tender (Marion, 1967). When post-mortem glycolysis was blocked by the injec-tion of neutralized sodium iodoacetate or epinephrine (de Fremery, 1966a; Sayre, 1970; Khan et a l . 1970) i t was shown that the meat was tender without aging (de Fremery and Pool, 1963; de Fremery 1966a). Muscles from turkeys anesthetized with sodium pentobar-b i t a l were more tender, as measured by shear value, than those from the unanesthetized control birds (Landes et a l . , 1971). De Fremery (1966a) concluded that beating, freezing, thawing, excising or cutting the muscle and el e c t r i c a l stimula-tion causes acceleration of rigor mortis in addition to acceler-Using injections of epinephrine at intervals of time before slaughtering or by allowing the birds to struggle freely just before and during slaughtering, Khan e_t a l . (1970) wore able to control the amount of pre- and post-mortem glycolysis in individual birds. By maintaining minimum ante-mortem and maximum post-mortem glycolysis i t was possible to achieve a pH of 6.2 just after slaughter and an ultimate pH of 5.7, which were considered desirable for achieving optimum tenderness after cooking. It may be concluded from the literature cited, that the post-mortem metabolism, in particular glycolysis, i s of utmost importance to the ultimate tenderness of poultry meat. The need to age muscles of avian and mammalian spe-cies post-mortem to achieve acceptable degrees of tenderness i s well known. The minimum c h i l l i n g (aging) period for ade-quate tenderization to occur in young chickens i s 2 - 4 hours post-mortem (Hanson e_t a l . , 1942; Pool ejt a l . , 1959; Dodge and Stadelman, 1959). Older chickens and turkeys require 8-12 hours (Klose et a l . , 1959; Dodge and Stadelman, 1959). Klose ejt a l . , (1961) found that a two-hour c h i l l i n g period plus a three-hour delay before freezing provided ade-quate opportunity for tenderization of 20-pound toms and 12-pound hens but was not adequate for six-pound fryer-roasters. When Large White Bronze and Small White fryer turkeys were subjected to varying c h i l l i n g procedures prior to freezing, Marion and Goodman (1967), found a significant effect of treat-ment on tenderness of 15 week-old birds but no significant effect on 18 or 27 week-old birds. The data indicated that con-tinuous c h i l l i n g was inadequate for the turkey-fryer tenderiza-tion. It was also shown, that smaller turkeys within a group had higher shear values. Brodine and Carlin : (1968) found that for 12 or 20 pound turkeys, the aging that occurs in a spin c h i l l e r for one hour following slaughter, was sufficient to ensure adequate tenderness in subsequently frozen and roasted meat. Scholtyssek and Klose (1967), used two strains and two age groups of turkeys and concluded from their study, that older birds may be limited to a shorter aging period with only a small percentage of resulting tough birds, younger birds aged for the same period of time contain a serious proportion of objectionably tough carcasses. Attempts have been made to explain this variation i n post-mortem aging requirements for different ages or size of turkeys. Marion (1967), hypothesized that the variation might be explained by differences in freezing rate for large and small carcasses. Larger turkey carcasses require a proportion-ately longer period to reach -4°C thus allowing more time for tenderization to occur. Physical Changes Post-Mortem Concurrent with and as a result of post-mortem meta-bolism in muscle, certain physical changes take place. The con-dition of rlgor-mortis is of primary concern in subsequent meat quality. The changes which take place with the passing of the muscle into rigor-mortis have been reviewed by Cassens (1966), Newbold (1966) and Goll (1968). Rigor-mort.is can l i teral ly be translated as "the stiffness of death" but Goll (1968), points out that rigor has two closely associated but quite different aspects. Rigor may be considered as; 1) a shortening or contraction of the muscle fibre, and 2) a loss of muscle extensibility. Loss of extensi-b i l i ty is further divided into a macroscopic phase and a molec-ular phase. The thesis developed is that, although molecular inextensibility is a necessary condition for the rigidity or stiffness observed in rigor, neither molecular nor macroscopic inextensibility are causes of rigor, i . e . , stiffening or harden-ing. Both are manifestations of rigor and are the result of ATP depletion in post-mortem muscle (Goll, 1968). Newbold (1966) showed that the normal features of post-mortem changes in muscle are; 1) that pH and the creatine phosphate concentration decline steadily; 2) acid labile P re-mains virtually constant until the creatine phosphate content has been greatly reduced; and 3) the maximum rate of decrease in extensibility is not attained : until the acid labile P has de-clined appreciably. He reported rapid loss of extension when the ATP level had fallen to about 307. of its in i t i a l level in horse muscle and chicken muscle; to about 257* and 507» in rabbit muscle at 17°C and 37°C respectively and to about 677. in beef muscle. In order to assess the relationship of chemical and physical changes post-mortem to ultimate meat quality, measure-ment of tenderness directly or indirectly i s required. Numerous devices have been developed to objectively measure meat tenderness (Pearson, 1966). By far the most common-ly employed indicator of tenderness i s the force required to shear a sample of meat. The devices commonly used to determine shear force are either the well known Warner-Bratzler or Allo-Kramer shear presses or their modifications. These devices pass a r i g i d plate of specified thickness through a meat sample of certain dimensions. As the blade passes through the meat, shear-ing and some compression of the sample take place. This type of measurement has been used widely as an indirect objective approx-imation of the response which a human would experience when eat-ing the meat in question. Correlations between sensory methods and the Warner-Bratzler are generally in a range of 0.60 to 0.85 (Pearson, 1963). This measure of tenderness has been employed to assess the effect of a variety of factors on meat tenderness. For example i t has been used by Buck et a_l. (1970), to determine the physical and chemical characteristics of free and stretched rabbit muscle; by Scholtyssek and Klose (1967), to measure sour-ces of va r i a b i l i t y in turkey tenderness; by Wells et a l . (1966), to measure the tenderness of freeze-dried chicken meat as re-lated to maturity of birds; by Welbourne et a l . (1968), to mea-sure the effect of cooling procedures in turkeys; by Goodwin et.al. (1969), to measure the influence of age, sex and diet-ary energy level on the tenderness of broilers; by Khan et a l . (1970), to determine the effect of pre- and post-mortem gly-colysis on poultry tenderness; and by Klose et a l . (1970), to measure the effect of contraction on tenderness of poultry muscle cooked in the pre-rigor state. A f a i r l y recent trend has been to elucidate the se-quence of physical changes of post-mortem muscle by the use of tension measuring devices (Jungle et a l . , 1967; Busch et a l . , 1967; Schmidt et a l . , 1968; Jungk et a l . , 1970; Schmidt et a l . , 1970). The isometric tension pattern has been shown to closely parallel the tenderness cycle and illustrates the tendency of a muscle to shorten (Jungk et a l . , 1970) Forrest (1968) summarized and briefly described the various instruments by which a number of parameters associated with rigor-mortis, can be measured. E l a s t i c i t y and extensibil-i t y can be measured by a rigorometer, a multi-unit isotonic-lso-metric rigorometer or a Myotron. The usual procedure involves the loading and unloading of a specified weight on an excised strip of parallel muscle fibres at regular intervals. The changes i n length of the muscle between the loaded and unloaded condition are measured. Tension and muscle length changes can be followed by an Isometer or a Myotron. These devices measure tension changes in muscles held isometrically. The muscle length i s held con-stant throughout the development of rigor by a balance beam with a servo mechanism controlling a counterweight position to keep the arm balanced. An ergbme.-t.er i s a v a i l a b l e t o measure the f o r c e and change i n l e n g t h i n muscle d u r i n g e i t h e r s t r e t c h i n g or shorten-i n g . The author f u r t h e r d i s c u s s e s the measurement of o t h e r p h y s i c a l parameters. E x t e n s i v e i n v e s t i g a t i o n s i n t o the post-mortem g l y -c o l y t i c p a t t e r n of t u r k e y muscle have not been r e p o r t e d , nor has the v a r i a t i o n i n a g i n g requirements f o r turkeys been s a t i s f a c -t o r i l y or completely accounted f o r . S i n c e tenderness of t u r k e y remains a c r i t i c a l q u a l i t y a t t r i b u t e , t h i s study was undertaken to c h a r a c t e r i z e the post-mortem g l y c o l y t i c and p h y s i c a l changes i n two age groups of t u r k e y s . MATERIALS AND METHODS Experiment I Muscle Samples The b i r d s used i n t h i s study were o b t a i n e d from a commercial tur k e y grower and t r a n s p o r t e d to the farm f a c i l i t i e s of the U.B.C. P o u l t r y Science Department. The b i r d s were White Cannon torn turkeys 14 weeks of age when r e c e i v e d . They were f e d a commercial 2 1 % p r o t e i n turkey grower mash d u r i n g a 1 3 day p e r i -od of adjustment b e f o r e being s l a u g h t e r e d . The b i r d s were caught and suspended by t h e i r l e g s , e x -sanguinated by an o u t s i d e neck c u t , and allowed t o b l e e d w i t h r e -s t r i c t e d movement of wings and l e g s . B l e e d i n g was allowed to proceed u n t i l completed (5 - 10 min.). Attempts were made to keep struggling to a minimum throughout the catching and slaughtering operations. The breast (muscles and the keel bone) was excised from the carcass. The l e f t Pectoralis super- f i c i a l i s muscle (nomenclature according to Harvey et a l . 1969) was dissected from the keel bone and used for pH measurement, and the right P. superficialis was dissected from the bone and used for determination of metabolic intermediate concentrations Timing of sampling was started 10 minutes after exsanguination. Samples were taken at "0", 15, 30, 60, 120, 180 minutes. pH pH was measured continuously with a Corning combina-tion probe electrode (Kastenschmidt et a l . , 1968 and Greaser et a l . , 1969) and a Corning model 10 expanded scale pH meter with a photovolt Varicord model 43 recorder. Throughout the pH measurement, the muscle was kept in an ice bath and the temperature change in the muscle over time was compensated for. Preparation of Muscle Extracts The muscle used for the determination of intermedi-ate levels was placed in crushed ice immediately after dissec-tion from the keel bone. Samples were obtained by discarding a \ cm. thick portion of the exposed muscle surface and immedi-ately excising sufficient muscle to make a 25 gm. sample. The sample was cut into \ cm. cubes and immediately dropped into liquid nitrogen. Sampling proceeded from the anterior to the posterior end of the muscle. The muscle samples were powdered according to the following modification of the method of Borchert and Briskey (1965). The muscle was removed from the liquid nitrogen (LJ^) and pulverized in a macro-model V i r t i s homogenizer for 1.5 minutes at a speed of 11,000 rpm. The powdered samples were then stored i n aluminum f o i l envelopes in u n t i l extracted. The powdered samples were extracted in the following manner: ten grams of powder (at LN^ temperature) was rapidly stirred into a 50 ml plastic tube containing enough 0.6 N per-chloric acid to give a 1 g : 3 ml dilution (ratio of wet tissue weight to extract volume, including muscle water assumed to be 737«, Swanson et a l . 1962). The extracts were centrifuged (15,000 x g) for 15 min-utes at 0°C. and the supernatant solutions decanted. The ex-tracts were then neutralized to the methyl orange end point with 5 M potassium carbonate and the precipitated potassium perchlor-ate allowed to settle out at 0°C. for at least 30 minutes, after which duplicate analyses for metabolic intermediates were completed within 72 hours. The analysis for the more labile intermediates, particularly adenosine triphosphate (ATP) and creatine phosphate (CP) were conducted f i r s t . Separate extracts for inorganic phosphate (P^) were prepared according to a modification of the procedure of Karpatkin et a l . (1964). The regularly prepared muscle powder was deproteinized with 0.6 N perchloric acid and immediately neutralized with a mixture containing 0.77 M Trisacetate and 1.25 M KOH. The samples were centrifuged at 15,000 x g to ob-tain the ortho-phosphate in the supernatant. Alkaline extracts for determination of reduced nicotinamide-adenine dinucleotide (NADH) were also prepared by methods outlined by Klingenberg (1963b). Analytical Methods Analyses for glucose - 6 - phosphate (G-6-P), fructose-6-phosphate (F-6-P), glucose-l-phosphate (G-l-P) and glucose were carried out in the same cuvette according to the method of Hohorst (1963a). Assays for fructose-1^6-diphosphate (FDP) glyceraldehyde-3-phosphate (GA3P) and dihydroxy acetone phosphate (DHAP) were conducted by the procedures outlined by Bucher and Hohorst (1963). The methods outlined by Czok and Eckert (1963) were used to determine 3-phosphoglyceric acid (3PGA), 2-phosphoglyceric acid (2PGA), phosphoenol-pyruvate (PEP), and pyruvate in the same assay. Lactate was determined by the method of Hohorst (1963b) and ^ -glycerophosphate (oC-GP) by the methods of Hohorst (1963c). Creatine phosphate (CP) and adenosine triphosphate (ATP) were determined in the same reaction vessel after the methods of Lamprecht and Stein (1963) and Lamprecht and Trautschold (1963). Adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were determined using the methods of Adam (1963). Nicotinamide-adenine dinucleotide (NAD) was determined by the method of Klingenberg (1963a) while reduced nicotinamide-adenine dinucleotide (NADH) was estimated by the method of Klingenberg (1963b). Glycogen was determined by the methods of Pfleiderer In a l l the above determinations, the procedures were used as indicated with only slight modifications in the con-centrations of intermediates, cofactors and enzymes. Some of these modifications were necessary because only cuvettes of 10 mm were used. A l l analyses were carried out with a Unicam-SP 800 model recording spectrophotometer. Total creatine was determined on the diluted neutral-ized perchloric acid extracts by the method of Ennor (1953). The resulting colour solutions were read in a spectrophotometer at 590 nm and the concentration determined from a standard curve. Inorganic phosphate was determined by the method of Berenblum and Chain (1938) on the neutralized extracts prepared as previously outlined by Karpatkin et a l . (1964). The extrac-tion and reduction were carried out in seperate flasks as out-lined by Ennor and Stocken (1950). The resulting colour com-plex was read i n a spectrophotometer at 710 nm and the concen-tration determined from a standard curve. Chemicals A l l chemicals used were of reagent grade. D i s t i l l e d water was used throughout the experiment. Enzymes, purified glycolytic intermediates and co-factors were purchased from Sigma Chemical Company, St Louis, Missouri. The animals used in this study were of the same popu-lation as those in Experiment I, and were maintained in the same f a c i l i t i e s and fed the same ration. The birds were slaughtered when they were 25 weeks old and a l l procedures of pH determination and sample preparation and analyses were identical to those of Experiment I. In making up the extracts, the muscle was taken to contain 737« water as determined by actxial moisture determina-tions on the muscle samples (Appendix A - Table I) . Experiment III Two additional 25-week old birds were used to deter-mine live muscle pH. The birds were anesthetized with ether to a "deep plane" of anesthesia (Fedde et a l . 1963). With the bird restrained on a modified surgical board, the skin was cut and the P. superficialis muscle exposed. A s l i t was made into the muscle and the combination pH probe electrode inserted. pH was recorded for 5 - 10 minutes as previously described (Exp. I ) . The bird was then given an overdose of ether and bled by an outside neck cut. The muscle was excised and pH recorded for 3 hours as previously described. Sodium iodoacetate (5mm) slurries were also made at the time intervals used in Experiment I and pH measured as described by Marsh (1952) (Appendix A -Table II). Five White Cannon torn turkeys of 14 weeks and 5 of 22 weeks were obtained from the same source and kept under con-ditions similar to those described in Experiment I until they were 19 and 27 weeks old respectively. Slaughter conditions and sampling of muscle were conducted as described previously. The l e f t P. superficialis was used to obtain three muscle strips of 10 cm x 1.5 cm x 1.5 cm and also to obtain samples for the determination of ATP. The muscle strips were used to determine the amount of shortening prior to rigor mortis and the extent of lengthening after rigor mortis. Sampling for ATP determina-tions was started 15 minutes after exsanguination, and samples were taken at "0" and "60" minutes. Preparation of the muscle extracts and the determination of ATP levels was asdescribed for Experiement I. The device used to measure the rigor development was designed from the idea put forth by Smith et a l . (1969) and Schmidt et a l . (1968) and was constructed by the Agricultural Engineering Department at U.B.C. It consists of a plexiglass tank 16.5 cm x 30 cm x 6 cm (outside measurements) and having 3 fixed plexiglass clamps at one end and moveable stainless steel and plexiglass clamps at the other. Each moveable clamp was attached by 6 lb. test monofibre fishing line running under and over two 6.5 cm diameter plexiglass pulleys to a set of weights. The pulleys were mounted on a brass shaft by means of sealed bearings (Plate 1). The weights attached to the moveable clamps exerted a load of 20 grams at the clamp as calibrated by a dynamometer. The whole tank was maintained i n a water bath. The muscle strips were allowed to contract freely in 15°C d i s t i l l e d water in the tank. Muscle strip length was measured as soon as the strips were placed i n the apparatus and at intervals and when contrac-tion had ceased (no change in length for 10 - 20 min.) the weights were attached to the strips via the clamp-pulley system. The muscle was then allowed to lengthen u n t i l maximum length was attained as measured by muscle strip length. Plate 1. Rigor measuring device showing the fixed ( A ) and moveable ( B ) clamps and weights ( C ) . Experiments I to III In the subsequent discussion of changes in concentra-tion of metabolites during the post-mortem period of measurement, the bird-to-bird variability in absolute concentration was large and therefore statistical significance of changes over time could not be generally demonstrated. However, the qualitative changes in concentration were relatively consistent from bird to bird and are reflected by the pattern of changes in average concentration Changes in post-mortem muscle pH of 15 week-old birds were quite varied for individual birds in Experiment I (Appendix A -Table VI). Some birds exhibited a rapid decline during the f irst 15 min. with a subsequent slow decline to the ultimate pH value; others showed a rapid i n i t i a l decline with a slight increase and then a steady decline or a continued increase to the ultimate pH value (Appendix B - Figure I). The lowest pH value reached was not always identical to the ultimate pH value attained. The low-est pH occurred anywhere from 0 to 180 minutes post-mortem. The average pH values for the five birds indicate that -pH dropped to a value of 5.99 at 15 min., rose to 6.03 at 30 min. and then declined to an ultimate value of 5.93 at 180 min. post-mortem. The 25 week-old birds of Experiment II showed consider-able variation In post-mortem pH values. However, the patterns of pH decline were similar (Appendix A - Table VII). A l l birds exhibited an i n i t i a l rapid decline and then a considerable in-crease over the next 45 minutes followed by a gradual increase to the ultimate value. The lowest pH value attained did not corre-spond to the f i n a l ultimate value and for a l l but one bird occurred at 15 min. post-mortem, (Appendix B - Figure 2). TABLE I - PH OF P. SUPERFICIALIS AT VARYING TIMES POST-MORTEM FOR 15 AND 25 WEEK-OLD TURKEYS (EXP. I AND I I ) . Time (min.) , Age (wks.) Post-mortem 15 25 0 6.11 + 0.17 1 6.17 t 0.14 15 5.99 ± 0.16 5.83 i 0.10 30 6.03 ± 0.18 5.88 ± 0.09 60 6.01 ± 0.15 5.93 ± 0.07 120 5.95 ± 0.08 5.96 + 0.07 180 5.93 + 0.10 5.95 + 0.06 lVa lues expressed as mean - standard deviation. The average pH values for the five 25 week-old birds dropped to a low of 5.83 at 15 min., then rose gradually to the ultimate value of 5.96 (Table I and Fig. 10B). At each measure-ment time the standard deviation of pH was lower for the 25 week-old birds than for the 15 week-old birds. To verify that the low pH values attained at "O" minutes post-mortem were r e a l i s t i c , Experiment III was conducted to de-termine the pH of muscle of an anesthetized bird. The pH, de-termined as previously described, was in the range of 6.90 to 7.10. Following the pH pattern of these muscles over the 180 min. post-mortem period showed similar rapid drops in pH, with an average ultimate pH of 6.19 and 6.06 as determined by the probe and slurry method respectively (Appendix A - Table II). The very high i n i t i a l pH values of bird 15 can be accounted for by the fact that the probe was not properly inserted into the muscle and was repositioned at about 30 min. post-mortem. The fact that the post-mortem pH values for these muscles were somewhat higher than those shown for the birds of Experiments I and II can probably be accounted for by the fact that the birds had been anesthetized with ether. This finding corresponds with that of Landes e_t a l . (1971), who found that muscle pH of anesthetized birds declined considerably slower than that of unanesthetized control birds, particularly during the f i r s t 6 hr. post-mortem. It can be seen from the limited results of Experiment III and also from the report of Kastenschmidt et a l . (1968), that the difference in pH between the two methods of measurement i s relatively small, especially for the last two time periods. Briskey (1964) had reported earlier that pH values taken with probe electrodes at the time of death are usually 0.2 pH units lower than the pH of macerated tissue at room temperature. The results of Experiment III indicate that the pH of the slurries was consistently lower than pH measured by the probe. A l l the glycolytic intermediates and co-factors, with the exception of creatine and inorganic phosphate were deter-mined by enzymatic methods. These methods depended on the coupling of a series of reactions, the end result of which was the reduction of. NAD and NADP or the oxidation of NADH and NADPH. The concentration of the intermediate or co-factor was calcu-lated by dividing the increase or decrease in absorbance, from the start to the completion of the reaction, by the appropriate molar extinction value of the NAD or NADP. Creatine and inorganic phosphate were measured by colorimetric means with comparison to a standard curve deter-mined i n the same manner. Intermediates of 15 week-old birds The concentration of each intermediate and co-factor determined for individual 15 week-old birds i s shown in Appendix A - Table VIII. These values represent the average of duplicate determinations. Table II contains the average levels of intermediates and co-factors at varying times post-mortem for the 15 week-old birds. The concentration of G-l-P shows a slight increase over time from 0.2579 ;uMoles/g to 0.4288 juMoles/g of tissue. Glucose-6-phosphate, was present at about ten times the con-centration of G-l-P for the i n i t i a l 30 minutes. Its concentra-tion Increased markedly, particularly during the period, from 60 to 180 minutes post-mortem. Fructose-6-phosphate shows a TABLE II Intermediate Time (min.) Post'-mortem or Co-factor 0 15 30 ATP^ 2.8253 + 2 .6459^ 2 .5619 ± 2. 4879 2 .1446 2 .6029 . ADP 1.0690 ± 0 .1877 0 .9560 ± 0. 3596 0 .9595 ± 0 .2272 AMP 0.2815 ± 0 .0766 0 .3164 ± 0. 1596 0 .2460 1 0 .1342 NAD 1.0363 + 0 .0949 0 .9446 + 0. 1524 0 .8914 ± 0 .1845 NADH 0.5247 + 0 .2757 0 .5399 0. 1959 0 .3370 ± 0 .1520 CP 3 Total Creatine- 1 0.9933 ± 1 .5579 1 .7303 + 2. 8600 0 .9063 + 1 .4289 2.7389 ± 1 .0619 3 .0119 ± 1. 2959 3 .0379 ± 1 .5410 Pi 14.3639 + 5 .7949 16 .6087 + 3. 2139 16 .1761 ± 2 .8310 G-l-P 0.2579 + 0 .2039 0 .2835 + 0. 1473 0 .2343 + 0 .1661 G-6-P 2.4715 + 1 .1200 2 .6020 1. 1105 2 .6787 ± 1 .1250 F-6-P 0.4156 + 0 .1873 0 .4622 + 0. 2015 0 .3892 + 0 .2172 FDP 0.0395 ± 0 .0366 0 .0378 + 0. 0417 0 .0400 ± 0 .0503 DHAP 0.0288 + 0 .0206 0 .0248 ± 0. 0201 0 .0307 ± 0 .0260 GA3P 0.0160 + 0 .0077 0 .0159 + 0. 0051 0 .0114 + 0 .0066 3 PGA 0.0097 + 0 .0066 0 .0080 + 0. 0051 0 .0112 ± 0 .0097 2 PGA 0.0061 + 0 .0021 0 .0089 0. 0073 0 .0065 ± 0 .0065 PEP 0.0114 ± 0 .0059 0 .0075 ± 0. 0054 0 .0174 ± 0 .0169 Pyruvate 0.3983 ± 0 .2193 0 .3350 + 0. 2462 0 .2982 + 0 .2979 Lactate 320.8059 ± 126.1000 344 .4151 ± 148.6000 344 .6626 ± 180.7000 eC-GP 1.0926 ± 0 .4740 0 .9591 + 0. 3479 0 .8742 + 0 .2269 Glucose 3.4799 ± 0 .9104 3 .5761 + 1. 0329 3 .4190 + 1 .3329 Glycogen^ 5.8759 ± 0 .5195 6 .2489 ± 0. 2173 6 .0705 + 0 .3174 Continued.... ^•Concentrations expressed as juMoles/g tissue. 2Abreviations as given in text. ^Concentration expressed as mg/g tissue. ^Concentration expressed as juMoles glucose/g tissue. ^Values are means 7 standard deviation. TABLE II (CONTINUED) Intermediate Time (min.) Post-mortem or Co-factor 60 120 180 ATP 1 .5783 ± 2.2749 0 .2742 X 0.3343 0 .0914 X 0 .1075 ADP 1 .0023 ± 0.1932 0 .7879 ± 0.2528 0 .8149 ± 0 .2429 AMP 0 .3162 + 0.1707 0 .6481 + 0.5531 0 .7619 + 0 .4727 NAD 0 .8904 + 0.1371 0 .8478 ± 0.1708 0 .9478 + 0 .1585 NADH 0 .3386 ± 0.0837 0 .3132 ± 0.1004 0 .3247 ± 0 .0520 CP 0 .2018 ± 0.3679 0 .1444 + 0.2413 0 .0869 + 0 .1288 Total Creatine 2 .5679 + 1.4049 2 .8460 + 1.5280 2 .9890 + 1 .6509 Pi 16 .0325 + 2.9089 15 .1777 + 2.1369 17 .8505 + 6 .7479 G-l-P 0 .2855 + 0.2456 0 .3268 ± 0.1894 0 .4288 ± 0 .3485 G-6-P 3 .6916 + 1.9300 5 .9251 + 3.0609 8 .0341 ± 3 .5370 F-6-P 0 .6025 + 0.3772 0 .9960 0.4214 1 .3431 0 .5537 FDP 0 .0364 + 0.0394 0 .0239 + 0.0306 0 .0072 ± 0 .0020 DHAP 0 .0210 + 0.0094 0 .0133 ± 0.0058 0 .0100 + i 0 .0064 GA3P 0 .0123 4- 0.0059 0 .0153 + 0.0130 0 .0105 *f- 0 .0101 3 PGA 0 .0067 + 0.0056 0 .0114 + 0.0068 0 .0110 4-— 0 .0051 2 PGA 0 .0074 + 0.0061 0 .0046 0.0057 0 .0072 + 0 .0045 PEP 0 .0094 + 0.0062 0 .0119 + 0.0122 0 .0167 + 0 .0334 Pyruvate 0 .3348 I 0.3396 0 .3425 ± 0.2761 0 .4152 ± 0 .3031 Lactate 273 .3271 + 84.3210 355 .9400 + 180.1000 358 .4657 ± 155.3900 oC-GP 0 .7744 + 0.2907 0 .8690 + 0.1750 0 .9586 + 0 .2722 Glucose 3 .8463 ± 0.9783 4 .1060 + 0.9918 4 .0545 + 1 .1919 Glycogen 6 .0923 + 0.0228 6 .0938 + 0.7776 5 .7133 ± 1 .5309 N3 Co similar rapid increase from 30 to 180 minutes. In comparison with the intermediates prior to FDP in the glycolytic cycle (Appendix B - Figure 3) those from FDP to pyruvate were present at much lower concentrations at a l l sampling times. Generally, the concentration of each of these intermediates, i.e., FDP, DHAP, GA3P, 3PGA, 2PGA, PEP and pyruvate, declined or remained relatively static over time post-mortem. Lactate concentration declined rapidly between 30 and 60 minutes but then increased to a level slightly above that of the i n i t i a l 30 minute period. Glucose increased gradually in concentration where-as glycogen decreased slightly in concentration (particularly during the period from 120 to 180 minutes) over the post-mortem time period measured. Co-factors of 15 week-old birds. Adenosine triphosphate concentration declined almost linearly from 2.8253 to 0.0914 /jMoles/g over the three hour period. Adenosine diphosphate concentration declined i n a manner similar to that of ATP, whereas AMP concentration re-mained relatively constant over the f i r s t 60 minute period, after which i t increased from 0.3162 to 0.7619 juMoles/g be-tween 60 and 180 minutes (Table II). Creatine phosphate concentration exhibited a very rapid decline during the period from 0 to 60 minutes and then a more gradual decrease to almost zero at 180 minutes. Total creatine, although showing some fluctuation over the three hour period of measurement, remained relatively constant. TABLE III Intermediate Time (min.) Post-mortem  or Co-factor 0 15 30 ATP^ 3.9219 + 1 .91005 2 .6369 4- 1.5849 2 .2245 1 .4319 ADP 0.9609 + 0 .1905 0 .9882 + 0.1614 0 .9991 ± 0 .2250 AMP 0.2643 + 0 .0625 0 .2367 + 0.0545 0 .2449 0 .0982 NAD 0.7184 + 0 .0479 0 .6939 + 0.0419 0 .6314 + 0 .1207 NADH 0.2626 + 0 .0973 0 .3226 + 0.1776 0 .2750 + 0 .1016 CP Total Creatine ° 0.8452 + 0 .6853 0 .5580 + 0.4042 0 .2644 0 .1901 5.4219 + 0 .7507 5 .3277 + 1.1239 5 .5129 + 0 .8949 p i 16.8082 + 3 .4769 18 .2879 + 3.9400 19 .8231 1 3 .3429 G-l-P 0.3369 + 0 .2795 0 .2265 + 0.1269 0 .2440 + 0 .1322 G-6-P 3.2238 + 1 .4289 2 .7225 ± 1.4879 2 .7007 1 .0000 F-6-P 0.3646 + 0 .1754 0 .3064 ± 0.1988 0 .3222 + 0 .1959 FDP 0.0547 + 0 .0450 0 .0158 0.0112 0 .0132 + 0 .0093 DHAP 0.0250 ± 0 .0178 0 .0168 + 0.0080 0 .0122 + 0 .0028 GA3P 0.0165 0 .0057 0 .0129 ± 0.0026 0 .0149 ± 0 .0038 3 PGA 0.0126 + 0 .0049 0 .0103 0.0048 0 .0126 ± 0 .0049 2 PGA 0.0119 0 .0042 0 .0113 -r 0.0001 0 .0114 ± 0 .0069 PEP 0.0225 + 0 .0089 0 .0208 + 0.0054 0 .0157 ± 0 .0061 Pyruvate 0.6570 + 0 .1401 0 .4691 + 0.1216 0 .3041 + 0 .0947 Lactate 368.4849 + 121.6000 358 .8349 ± 96.3590 338 .4682 ± 11 02.8900 oC-GP 0.7786 0 .2532 0 .6899 + 0.1921 0 .5702 + 0 .2034 Glucose , Glycogen 4.1604 ± 0 .6736 4 .0102 ± 0.6586 4 .3341 + 0 .4369 6.1342 ± 2 .8290 5 .9008 ± 2.5500 6 .0559 + 2 .7090 Continued •'•Concentrations expressed as ;uMoles/g tissue. ^Abreviations as given i n text. •^Concentration expressed as mg/g tissue. ^Concentration expressed as AiMoles glucose/g tissue. ^Values are means - standard deviation. TABLE I I I (CONTINUED) I n t e r m e d i a t e o r C o - f a c t o r Time ( m i n . ) P o s t - m o r t e m 60 120 180 ATP ADP AMP NAD NADH CP T o t a l C r e a t i n e p i G - l - P G - 6 - P F - 6 - P FDP DHAP GA3P 3 PGA 2 PGA P E P P y r u v a t e L a c t a t e «rf~GP G l u c o s e G l y c o g e n 1 .4744 + 1 . 4 2 5 9 0 . 9 8 2 6 + 0 . 3 6 8 8 0 . 2 7 7 9 ± 0 . 1 1 5 0 0 . 5 6 6 0 + 0 . 1 4 3 0 0 . 2 7 1 0 ± 0 . 1 0 2 1 0 .1616 + 0 . 1 6 6 9 5 . 3 5 9 1 0 . 9 2 3 7 1 9 . 2 8 4 1 ± 2 . 4 6 7 9 0 . 2 3 2 5 ± 0 . 1 8 3 6 3 . 0 8 2 9 + 0 . 9 3 7 9 0 . 3 2 6 4 ± 0 . 1 2 0 2 0 . 0 0 7 8 + 0 . 0 0 4 5 0 . 0 1 4 8 + 0 . 0 0 2 8 0 . 0 1 3 9 + 0 . 0 0 3 4 0 . 0 1 2 6 0 . 0 0 2 6 0 . 0 0 9 1 + 0 . 0 0 5 0 0 . 0 1 4 0 + 0 . 0 0 6 3 0 . 2 5 9 9 + 0 . 1 2 4 2 3 0 7 . 4 5 1 0 + 9 1 . 0 3 9 0 0 . 5 2 9 0 + 0 . 1 7 2 0 4 . 1 2 5 8 + 0 . 5 3 0 7 6 .2120 + 2 . 9 0 4 9 0 . 3 4 8 2 t 0 . 2 0 6 0 0 . 9 1 7 1 t 0 . 3 5 7 7 0 . 8 2 0 5 3 0 . 5 8 5 3 0 . 5 7 8 3 * 0 . 1 4 9 9 0 . 2 9 4 6 J 0 . 2 4 6 4 0 . 1 0 2 9 - 0 . 0 6 5 2 5 . 0 1 6 3 ± 1 . 2 9 0 9 1 9 . 3 7 9 1 ± 3 . 8 8 1 9 0 . 2 9 0 5 t 0 . 2 2 5 0 5 . 1 2 6 0 ± 3 . 3 0 1 9 0 . 7 5 5 9 ± 0 . 5 0 3 7 0 . 0 0 7 2 ± 0 . 0 0 2 1 0 . 0 1 3 3 ± 0 . 0 0 2 8 0 . 0 1 3 4 ± 0 . 0 0 2 8 0 . 0 1 3 2 t 0 . 0 0 3 8 .0.0102 ± 0 . 0 0 4 7 0 . 0 1 5 7 ± 0 . 0 0 2 5 0 . 2 7 5 6 ± 0 . 1 2 2 5 3 2 8 . 2 3 7 8 ± 9 4 . 7 2 9 0 0 . 5 0 7 9 ± 0 . 2 0 9 2 4 . 7 1 6 0 ± 0 . 4 3 5 6 5 . 9 7 9 1 ± 2 . 6 2 8 0 0 . 1 2 9 0 ± 0 . 0 7 9 7 0 . 7 6 4 2 - 0 . 2 5 9 7 0 . 9 0 0 1 ± 0 . 5 9 1 6 0 . 6 2 2 2 i 0 . 1 3 5 5 0 . 3 4 7 3 t 0 . 1 9 7 4 0 . 0 7 3 7 - 0 . 0 7 3 2 5 . 4 2 1 3 ± 0 . 9 5 7 8 1 7 . 8 6 1 5 ± 4 . 5 2 2 9 0 . 2 9 6 3 ± 0 . 2 1 9 5 7 . 3 4 8 6 ± 4 . 0 0 2 9 0 . 9 9 3 5 t 0 . 6 6 1 7 0 . 0 0 4 7 ± 0 . 0 0 2 8 0 . 0 1 1 2 ^ 0 . 0 0 2 3 0 . 0 0 9 2 $ 0 . 0 0 4 5 0 . 0 1 3 1 - 0 . 0 0 6 9 0 . 0 1 1 3 ± 0 . 0 0 5 7 0 . 0 1 6 3 ± 0 . 0 0 2 8 0 . 2 4 1 5 ± 0 . 1 0 2 4 3 6 9 . 2 9 6 2 ^ 1 1 8 . 6 0 0 0 0 . 5 9 5 8 ± 0 . 2 1 1 6 4 . 8 6 0 7 ± 0 . 4 0 9 6 5 . 5 1 2 8 ± 2 . 2 6 9 0 The concentration of NAD decreased slightly from 0 to 120 minutes and then increased. NADH was present at about 507„ of the concentration of NAD and dropped rapidly be-tween 15 and 30 minutes after which i t remained essentially constant (Table II). Intermediates of 25 week-old birds. The concentration of each intermediate and co-factor determined for individual 25 week-old birds i s shown in Appendix A - Table IX. These values represent the average of duplicate determinations. Table III contains the average levels of intermediates and co-factors over varying times post-mortem for the 25 week-old birds. Glucose-l-phosphate concentration fluctuated during the post-mortem period but showed a slight net decrease from 0 to 180 minutes. Glucose-6-phosphate was present in the tissue at a considerably higher concentration than G-l-P and increased from 3.2238 to 7.3486juMoles/g tissue between 0 and 180 minutes. Fructose-6-phosphate concentration was quite stable up to 60 minutes post-mortem after which i t increased rapidly to a maximum at 180 minutes. Fructose-1, 6-diphosphate-and the intermediates following i t , were contained in the tissue at levels considerably lower than the intermediates prior to FDP. These intermediates, i.e., FDP, DHAP, GA3P, 3PGA, 2PGA, PEP and pyruvate, generally declined or remained relatively constant over time. Lactate concentration declined steadily from 0 to 60 minutes after which i t increased steadily to a concentration of 369.2962 /jiMoles/g at 180 minutes, slightly above the i n i t i a l concentration. Glucose concentration, although fluctuating somewhat, slowly increased over the three hour period, whereas glycogen concentration, similarily fluctuating, decreased slightly over time. Co-factors of 25 week-old birds. Adenosine triphosphate concentration declined rapidly whereas ADP concentration increased slightly for the f i r s t 30 minutes and then decreased rapidly over the next 150 minutes. Adenosine monophosphate concentration remained essentially constant for the i n i t i a l 60 minutes after which i t increased very rapidly from 60 to 120 minutes and continued to increase, but more slowly during the last 60 minutes post-mortem (Table III). Creatine phosphate concentration declined very rap-idly during the i n i t i a l 60 minutes and continued to decrease to 0.0737 juMoles/g tissue at 180 minutes post-mortem. Creatine concentration although fluctuating, remained essentially con-stant throughout the time period of measurement. Inorganic phosphate concentration increased considerably during the in-i t i a l 30 minutes and then decreased gradually to 180 minutes post-mortem (Table III). The concentration of NAD decreased slightly whereas NADH concentration increased slightly over the total time period of measurement (Table III). 60 120 180 60 120 180 TIME* (NUN.) POST-MORTEM F i g u r e 1. Comparisons of c o n c e n t r a t i o n s of some g l y c o l y t i c i n t e r m e d i a t e s i n P. s u p e r f i c i a l i s muscles from 15 week-old (O 0) and 25 week-old t u r k e y s . a) < UJ -I o . 0 4 0 ,020 .00S 1 eC-QP 60 120 180 " 60 TIME (MIN.) POST-MORTEM 120 180 Figure 2. Comparisons of concentrations of some glycolytic intermediates in P. superficialis muscles from 15 week-old (O——O) and 25 week-old turkeys. CO < C9 CO U J - J o A .028 .009 .006 J.007 ! r P Y R U V A T E .007 .004 120 TIME 160 60 .) P0ST-M0RTE5 120 ISC Figure 3. Comparisons of concentrations of some glycolytic intermediates in P. superficialis muscles from 15 week-old (O O) and 25 week-old turkeys. F i g u r e 4. Comparisons of c o n c e n t r a t i o n s of some g l y c o l y t i c i n t e r m e d i a t e s i n and pH v a l u e s of P. s u p e r f i c i a l i s muscles from 15 week-old (O O) and 25 week-old turkeys . Glycogen c o n c e n t r a t i o n i s ex-pressed as uMoles of g l u c o s e / g . 3 W w CO kJ o 0.95 0.85 0.75 60 120 TIME 180 60 .) P0ST~M0RTEf 120 ISO F i g u r e 5. Comparisons of c o n c e n t r a t i o n s of some g l y c o l y t i c c o - f a c t o r s i n P. s u p e r f i c i a l i s muscles from 15 week-old (O -U) and 25 week-old t u r k e y s . ( A a) 0 4'— « — i I 6 0 1 2 0 1 3 0 TIME (MIN.) POST-MORTEM F i g u r e 6. Comparisons of c o n c e n t r a t i o n s of some g l y c o l y t i c c o - f a c t o r s i n P. s u p e r f i c i a l i s muscle from 15 week-old (O O) and 25 week-old tu r k e y s (& . C r e a t i n e c o n c e n t r a t i o n i s expressed as mg/g. Comparison of Intermediates and Co-factors for 15 and 25  week-old birds. The standard deviation associated with the concentra-tion of each intermediate and co-factor was relatively large regardless of age group or post-mortem time (Tables II and III). The magnitude of the var i a b i l i t y in the data is further demon-strated by the average coefficients of v a r i a b i l i t y (Table IV). It can be ascertained readily from the means and standard de-viations presented that with few exceptions no significant differences (P=0.05) in concentration of intermediates and co-factors existed between the two age groups.*- The exceptions were NAD and total creatine which were significantly higher in the 15 and 25 week-old birds respectively at a probability level of 5% in a l l cases except one. The large v a r i a b i l i t y encountered, however, i s not unique to the results reported here. Bodwell et a l . (1965), reported similar variations for beef muscle at slaughter; e.g. la c t i c acid, 13.1 ± 6.0 ;uMoles/g; ATP, 6.4 - 1.2 juMoles/g; crea-tine phosphate, 9.1 - 3.2 juMoles/g; ortho P, 22.1 - 3.1 micro-atoms/g. Bodwell et a l . (1966), reported ATP concentrations of 5.6 - 4.1 and 3.2 - 3.7 juMoles/g tissue in pork muscle at 13 and 166 minutes post-mortem respectively. Hall et a l . (1968) • Because almost every datum contained in Tables II and III i s based on n=5 (for the few exceptions n-3 or 4; see Appendix A -Tables VIII and IX) the standard deviations presented are each approximate estimates of \ the 95% confidence interval for their corresponding mean, i.e. 1.96 £ ~ s. Thus, the signi-is AVERAGE COEFFICIENTS OF VARIABILITY"" ASSOCIATED WITH THE PLOTS OF THE MEAN CONCENTRATIONS OF INTERMEDIATES AND CO-FACTORS OVER TIME POST-MORTEM Intermediate or co-factor Age Group 15 Weeks 25 Weeks ATP 116.01 65.17 ADP 26.66 29.23 AMP 55.59 44.98 NAD 16.38 17.47 NADH 34.45 51.20 CP 162.90 81.89 Total Creatine 48.87 18.64 Pi 24.54 19.54 G-l-P 71.19 70.61 G-6-P 46.33 47.55 F-6-P 48.44 57.31 FDP 98.80 61.67 DHAP 64.94 33.71 GA3P 61.20 29.08 3 PGA 68.00 37.75 2 PGA 80.88 41.36 PEP 98.23 30.41 Pyruvate 80.34 35.51 Lactate 43.28 30.14 oC-GP 31.16 34.21 Glucose 28.84 12.20 Glycogen 10.14 44.32 ^•Average coefficient of var i a b i l i t y is the arithmetic average of the coeffients of var i a b i l i t y for each of the 6 post-mortem sampling times. reported ATP, ADP and AMP concentration in turkey muscle 4.5 minutes after slaughter, of 3.1 - 1.0, 1.34 i 0.52 and 0.18 - 0.08 juMoles/g respectively. The average concentration of a l l intermediates and co-factors in turkey breast muscle are similar in magnitude to those reported by Kastenschmidt et a l . (1968) for "slow" and "fast-glycolyzing" porcine muscles. The very rapid decline of creatine phosphate for both 15 and 25 week-old birds parallels the rapid decline of ATP concentration. Creatine phosphate in fact is depleted at an earlier time post-mortem than is ATP, particularly when con-sidering individual birds (Appendix A - Table VIII and IX). This i s in agreement with the findings of Newbold (1966) and Kadtenschmidt et a l . (1968). ficance of differences between corresponding means from each of the two age groups can be approximated from an assessment of the degree of overlap of the ranges of concentrations represented by x + s as presented in the tables. The f a c t t h a t o n l y few s i g n i f i c a n t d i f f e r e n c e s i n c o n c e n t r a t i o n of i n t e r m e d i a t e s and c o - f a c t o r s were found be-tween 15 and 25 week-old b i r d s d i d not p r e c l u d e the p o s s i -b i l i t y of d i f f e r e n c e s i n the g l y c o l y t i c c o n t r o l s i t e s f o r the two age groups. Some p a i r s of means, both between age groups and between i n t e r m e d i a t e s w i t h i n an age group, d i f f e r e d by s e v e r a l orders of magnitude and the l a c k of s t a t i s t i c a l s i g -n i f i c a n c e i s l i k e l y predominately a r e f l e c t i o n of the r e l a -t i v e l y low number of samples (5) f o r the v a r i a b i l i t y encounter-ed. F o r t h i s reason and because the author was unaware of any s t u d i e s of g l y c o l y t i c c o n t r o l s i t e s i n post-mortem tur k e y muscle i t was c o n s i d e r e d germane to estimate the s u s c e p t i b i l -i t y of the v a r i o u s g l y c o l y t i c r e a c t i o n s to c o n t r o l . To accom-p l i s h t h i s , mass a c t i o n r a t i o s of the m a j o r i t y of the g l y -c o l y t i c enzymes were c a l c u l a t e d f o r each age group a c c o r d i n g to the methods of Minakami et a l . (1966) as summarized In T a b l e V. The r e s u l t s appear i n T a b l e VI along w i t h the appar-ent e q u i l i b r i u m c o n s t a n t s taken from W i l l i a m s o n (1965) and Minakami e_t a l . (1966). By comparing mass a c t i o n r a t i o s w i t h the known e q u i l i b r i u m constants of the enzymes concerned some i n d i c a t i o n of t h e i r s u s c e p t i b i l i t y to c o n t r o l can be a c h i e v e d . Minakami e_t a l . (1966), c o n s i d e r any r e a c t i o n w i t h a mass ac-t i o n r a t i o d i f f e r i n g from the e q u i l i b r i u m constant by a f a c t o r Enzymes Mass A c t i o n R a t i o H e x o k i n a s e (HK) ( G-6 - P ) ( A D P ) ( G l u c o s e )\ATF) P h o s p h o g l u c o m u t a s e (PGM) (G-6-P) P h o s p h o g l y c o i s o m e r a s e ( P G I ) ( F-6 - P ) ( G-6 - P ) P h o s p h o f r u c t o k i n a s e (PFK) (FDP) (ADP) ( P~6 - P ) ( A T P ) A l d o l a s e ( A i d ) (GA3P)(DHAP) (FDP) P h o s p h o t r i o s e i s o m e r a s e ( P T I ) (GA3P) A i d x P T I (GA3P) 2 G l y c e r a l d e h y d e p h o s p h a t e (3PGA)(ATP)(NADH) d e h y d r o g e n a s e x p h o s p h o g l y c e r i c (CA3P)(ADP)(P<)(NAD) k i n a s e (GAPDH) x (PGK) P h o s p h o g l y c e r a t e mutase (PGM) (2-PGA) (3-PGA)' E n o l a s e ( E n o l ) ( P E P ) (2-PGA) P y r u v a t e k i n a s e (PK) ( P y r u v a t e ) ( A T P ) ( P E P ) (ADP) L a c t a t e d e h y d r o g e n a s e (LDH) ( L a c t a t e ) ( N A D ) ( P y r u v a t e ) ( N A D H ) o f l e s s t h a n 10 z t o 10 , as b e i n g i n q u a s i - e q u i l i b r i u m . Because t h e f r e e e n e r g y change f o r r e a c t i o n s c l o s e t o e q u i l i b r i u m i s s m a l l , t h e s e r e a c t i o n s a r e n o t n o r m a l l y s u s c e p t i b l e t o c o n t r o l . MASS ACTION RATIOS CALCULATED FROM "0" MINUTE DATA ON GLYCOLYTIC INTERMEDIATES AND CO-FACTORS IN MUSCLES OF 15 and 25 WEEK-OLD BIRDS R e a c t i o n ^ Apparent E q u i l i b r i u m Mass A c t i o n R a t i o s Constant 15 wks 25 wks HK 4 x i o " 4 2.69 X 10" 1 1.91 X l O " 1 PGM 5.5 X l O " 2 9.58 9.56 PGI 0.28 - 0.45 1.68 X i o - i 1.13 X i o - i PFK 1-1.2 X 103 3.59 X 10-2 3.70 X 10-2 A l d o l a s e 0.7-1.3 X 1 0 - 4 1.16 X l O " 2 7.30 X i o - 3 PTI 4-5 X 10-2 5.55 X i o - i 6.60 X i o - i A i d . x PTI 4-6.5 X 1 0 - 6 6.44 X 10" 3 4.81 X I O " 4 GAPDH x PGK 2-15 X 102 5.65 X l O " 2 6.72 X IO" 2 PGM 1-1.8 X i o - i 6.29 X i o - i 9.44 X i o - i E n o l . 2.8 - 6.3 1.87 1.89 PK 2-20 X 103 92.24 118.67 LDH 1.6 X 104 1.59 X 103 1.52 X 103 l A b r e v i a t i o n s as g i v e n i n Tab l e V. The data o f Table VI i n d i c a t e no apparent d i f f e r e n c e i n the post-mortem metabolism of the 15 and 25 week-old age groups. With the e x c e p t i o n of the A l d o l a s e x pho s p h o t r i o s e isomerase r e a c t i o n , the mass a c t i o n r a t i o s of the two groups d i f f e r by l e s s than t w o - f o l d . Kastenschmidt e t a l . (1968) reported on the basis of their investigations, that the different post-mortem glycolytic rates exhibited by the vari-ous strains of swine used, could probably be explained by differences in post-mortem glycolytic control. In a subse-quent report, Kastenschmidt (1970) stated that control pro-perties of the two rates of glycolysis are unlikely to be different. For both age groups, the probable control sites are the reaction steps catalyzed by hexokinase, phosphofructo kinase, aldolase and triosphosphate isomerase, glyceraldehyde phosphate dehydrogenase and phosphoglycerokinase and pyruvate kinase. The reactions at these points can be considered to be severely displaced from equilibrium. Manipulation of the 120 minute data in a manner similar to that shown in Table VI gave similar results. Williamson (1965), showed that in the glycolysis of rat heart tissue, hexokinase, phosphofructkinase, glyceralde-hyde phosphate dehydrogenase and pyruvate kinase were far dis-placed from equilibrium and were therefore operational in the glycolytic flux. Minakami et a l . (1966) showed that the reactions catalyzed by hexokinase, phosphofructokinase and pyruvate kinase were rate limiting steps in the glycolytic process in erythrocytes. Phosphorylase, phosphofructokinase and pyruvate kinase have been implicated in the post-mortem glycolytic control of porcine muscle (Kastenschmidt et a l . , 1968). Southard et a l . (1969), describe the preparation of a chicken breast muscle mitochondrial fraction which is capable of aerobic respiration or lactate production and in which the hexokinase catalyzed phosphorylation of glucose is the rate limiting step under both the aerobic and anaerobic conditions. If no control were exerted on the glycolytic flux post-mortem, then glycogen would be stoichiometrically con-verted to l a c t i c acid and a l l intermediate concentrations would remain constant. From Tables II and III and Figures 1 - 6 i t can be seen that while glycogen concentration de-creased, glucose, G-l-P, G-6-P and F-6-P concentrations i n -creased with time post-mortem. A l l four of these intermedi-ates remained relatively constant over the i n i t i a l 30 minute period, after which the concentration began to rise, indica-ting an inhibition of phosphofructokinase and thus a buildup of intermediates prior to F-6-P phosphorylation. The inter-mediates subsequent to this reaction were markedly reduced in concentration and declined in concentration over time. The decline was approximately parallel in DHAP, GA-3-P, 3PGA, 2PGA and PEP. These findings substantiate the evidence from mass action ratios which indicates that the phosphofructo-kinase catalysed reaction i s a glycolytic control s i t e . ATP Metabolism Because of the well established importance of ATP concentration and rate of disappearance to post-mortem muscle extensibility and subsequent physical and chemical changes (e.g., Newbold, 1966; de Fremery et a l . , 1963; Khan, 1971) and because the data for ATP concentration (Tables II and III) suggested differences among birds, an attempt was made to categorize the 10 birds on the basis of rate of ATP disappear-ance. The ATP concentration at 15, 30, 60, 120 and 180 min. post-mortem as a percentage of i n i t i a l ATP concentration was calculated for each bird (Table VII). These values tend to f a l l into two distinct groups, each containing several birds of each age. The two groups were evident at the 15, 30 and 60 min. but not at the 120 and 180 min. time periods. The groups are most clearly distinguished on the basis of the 60 min. data for which the groups exhibited ranges of ATP con-centration as a percentage of i n i t i a l ATP concentration of 5.16 to 32.49% and 52.81 to 76.00%. The latter group contain-ed birds numbered 2, 6, 10 and 11 and hereafter w i l l be re-ferred to as Group I. The former group contained birds numbered 3, 4, 5, 12, 13 and 14 and w i l l henceforth be re-ferred to as Group II. Lactic acid and pH Inspection of the l a c t i c acid concentration and pH data for both age groups, on either an individual bird or mean basis, shows a lack of agreement. It i s generally reported, that since l a c t i c acid is the end product of glycolysis, pH can be taken as an indicator of the extent of post-mortem gly-colysis (e.g., Kastenschmidt et a l . , 1968 and Khan et a l . , 1970). Bodwell e_t a l . (1965), report that in beef during the i n i t i a l 24 hour post-mortem period, 46.5 ;uM of la c t i c acid/g of muscle were produced for every unit decrease in pH. The workers report values showing similar relationships for other species (Bodwell et a l . , 1966). Gunther et a l . (1966), however, after investigating the changes of lactate concen-tration and pH values at varying times post-mortem on differ-ent samples of beef and pork muscles, reported that the re-sults indicated no simple correlation between lactate con-centration and pH values. They further reported a consider-able difference in the results obtained between the chemical and enzymatic method of determining la c t i c acid. The concentration of la c t i c acid reported in the pre-sent study (273.3 - 369.3 >uMoles/g) appears quite high in com-parison to other reported concentrations. Bodwell et a l . (1965), report la c t i c acid concentrations in beef ranging from 13.1 to 84.6 uMoles/g for i n i t i a l and 180 minutes post-mortem respectively. Kastenschmidt et a l . (1968), report concentra-tions ranging from about 30 to 115 juMoles/g tissue. Shrimpton (1960), reported concentrations of approximately 1 mg/g one minute after slaughter to a maximum of about 8 mg/g fresh weight 10 minutes after slaughter. Depending on the method of slaughtering or the treatment before slaughter, la c t i c acid concentrations after slaughter has been reported to range from 2.6 to 9.C mMoles/lOOg of chicken muscle (Khan et a l . , 1970). The method of measurement and the results obtained in the present study were rechecked. It is suggested that the differences in la c t i c acid concentration between the present study and those reported in the literature might be explained in part by.species differences. TABLE VII ATP CONCENTRATION AS A PERCENTAGE OF INITIAL ATP CONCENTRATION Bird No. Age (wks) Time (min.) Post -mortem 15 30 60 120 180 2 15 117.05% 111.37 61.37 9.09 2.27 3 15 57.14 28.57 14.28 14.28 2.39 4 15 49.93 29.95 5.16 2.58 5.16 5 15 143.77 31.89 32.49 0 0 6 15 88.29 83.77 74.25 11.42 3.79 10 25 79.77 68.54 52.81 8.99 2.25 11 25 72.00 68.00 76.00 16.00 4.00 12 25 58.18 50.91 14.54 7.27 0 13 25 57.32 44.10 11.76 2.94 2.94 14 25 55.17 27.59 20.69 17.24 20.69 pH Pattern of Group I and Group II Average muscle pH for each group at varying times post-mortem appear in Table VIII and Figure 10B. Although the zero time pH values were similar, the two groups exhibited a considerable difference in the rate of decline. The pH of Group I dropped rapidly from 6.11 at 0 min. to 6.01 at 15 min., rose to 6.05 at 30 min., remained constant from 30 to 60 min. and subsequently decreased to 5.99 at 120 minutes. The f i n a l pH was 5.99. Group II exhibited an extremely rapid pH drop from 6.16 at 0 min. to 5.85 at 15 min., after which i t gradually rose to 5.93 during the next 105 min. and subsequently declined slightly to the ultimate pH of 5.92 at 180 minutes. TABLE VIII COMPARISON OF pH VALUES AT VARYING TIMES POST-MORTEM FOR GROUP I AND GROUP II TURKEYS Time (min.) Group I Group II Post-mortem 0 6.11 + 0.171 6.16 + 0.14 15 6.01 + 0.16 5.85 + 0.11 30 6.05 ± 0.18 5.89 + 0.10 60 6.05 + 0.14 5.91 + 0.07 120 5.99 0.30 5.93 + 0.08 180 5.99 ± 0.28 5.92 0.09 ^Values expressed as mean - standard deviation. Glycolytic Intermediates and Co-factors of Groups I and II  Using the data of Appendix A - Table VIII and XI, averages for every intermediate and co-factor over time post-mortem were calculated for each group. The averages and standard deviations are tabulated in Tables IX and X for Groups I and II respectively. Intermediate or Co-Factor Time (min.) Post-mortem 0 15 30 ATP 2 5.0731 2.03005 4 .4282 1 .6740 4. 0886 + 1 .5540 ADP 0.9702 ± 0.1312 0 .8967 + 0 .3167 0. 9887 + 0 .2589 AMP 0.2013 + 0.0645 0 .2485 0 .1696 0. 1808 + 0 .1056 NAD 0.8354 + 0.1791 0 .8483 + 0 .1519 0. 8444 + 0 .1616 NADH 0.2985 ± 0.1744 0 .4287 + 0 .2523 0. 3336 ± 0 .1975 CP 1.7099 + 1.5480 2 .3318 ± 3 .0090 1. 1355 + 1 .5400 Total Creatine-* 4.4551 + 2.2000 4 .5442 + 2 .2260 4. 8319 JU 2 .3580 p i 12.5319 ± 5.4870 14 .3706 ± 1 .0910 15. 6725 i 3 .0920 G-l-P 0.2967 + 0.1568 0 .2338 + 0 .1061 0. 1734 t 0 .1041 G-6-P 3.6812 1.2630 3 .4548 ± 1 .2000 3. 1420 ± 1 .0680 F-6-P 0.4853 0.1015 0 .4846 ± 0 .1441 0. 3539 + 0 .1907 FDP 0.0628 ± 0.0392 0 .0509 + 0 .0393 0. 0561 0 .0463 DHAP 0.0321 + 0.0214 0 .0286 ± 0 .0204 0. 0342 0 .0288 GA3P 0.0127 ± 0.0052 0 .0159 X 0 .0031 0. 0159 + 0 .0043 3PGA 0.0093 ± 0.0063 0 .0116 + 0 .0050 0. 0095 ± 0 .0059 2 PGA 0.0087 + 0.0051 0 .0138 + 0 .0038 0. 0085 0 .0049 PEP 0.0156 ± 0.0085 0 .0137 ± 0 .0083 0. 0111 0 .0045 Pyruvate 0.4738 + 0.2257 0 .2818 ± 0 .1556 0. 1302 0 .1010 Lactate 236.7775 + 99.8900 265 .2485 + 119.8000 239. 0618 110.9000 os-GP 0.7456 0.2943 0 .6955 ± 0 .2579 0. 6210 + 0 .2379 Glucose 3.6599 ± 0.3851 3 .4585 + 0 .5621 3. 3538 + I .1570 Glycogen^ 6.8436 1.3470 7 .0212 ± 0 .8788 6. 9922 + 1 .3910 Continued •^-Concentrations expressed as /jMoles/g tissue. 2Abreviatiohs as given in text. •^Concentration expressed as mg/g tissue. ^Concentration expressed as juMoles glucose/g tissue. ^Values are means £ standard deviation. Intermediate or Co-factor Time (min.) Po st-mortem 60 120 180 ATP 3 .3431 + 1 .4890 0 .5633 + 0 .2224 0. 1578 + 0 .0853 ADP 1 .1837 ± i 0 .0966 0 .9686 + 0 .3835 0. 7919 0 .2756 AMP 0 .2183 -T 0 .0445 1 .1779 ± 0 .6378 1. 1922 0 .6258 NAD 0 .8075 ± 0 .1931 0 .7887 ± 0 .1717 0. 7825 ± 0 .1589 NADH 0 .3737 ± 0 .1013 0 .2501 + 0 .2068 0. 2924 JL J. 0 .1044 CP 0 .3616 ± 0 .3794 0 .2351 + 0 .2281 0. 1083 J _ t 0 .1375 Total Creatine 4 .5284 + 2 .4380 4 .6228 + 2 .4750 4. 8783 + 2 .4570 Pi 15 .1368 ± 2 .7530 14 .4796 ± 1 .5900 17. 7213 7 .9790 G-l-P 0 .1877 ± 0 .1844 0 .3116 + 0 .1769 0. 3031 + 0 .2428 G-6-P 3 .5855 ± 1 .2660 8 .6594 1 .1670 10. 7076 0 .5615 F-6-P 0 .4430 ± 0 .2719 1 .2177 + 0 .2876 1. 6747 ± 0 .2172 FDP 0 .0449 ± 0 .0402 0 .0308 ± 0 .0310 0. 0065 + 0 .0024 DHAP 0 .0227 + 0 .0099 0 .0171 + 0 .0036 0. 0089 0 .0063 GA3P 0 .0138 + 0 .0037 0 .0105 + 0 .0043 0. 0039 0 .0049 3 PGA 0 .0086 0 .0050 0 .0109 + 0 .0053 0. 0132 + 0 .0065 2 PGA 0 .0061 0 .0039 0 .0052 ± 0 .0047 0. 0113 0 .0057 PEP 0 .0079 + 0 .0039 0 .0089 + 0 .0066 0. 0112 + 0 .0057 Pyruvate 0 .1195 ± 0 .0823 0 .1903 ± 0 .0675 0. 1610 0 .0428 Lactate 245 .3914 98.1300 259 .9055 92.4200 247. 6486 + 1 10.7000 oc-GP 0 .5162 ± 0 .1709 0 .5628 ± 0 .2617 0. 6155 0 .2269 Glucose 3 .8333 + 0 .5330 4 .7309 + 0 .5383 4. 7871 ± 0 .6946 Glycogen 7 .1153 + 1 .2460 6 .5375 + 1 .4010 5. 6754 + 1 .8540 The concentrations of glycolytic intermediates and co-factors do not di f f e r greatly between Groups I and II (Figures 7 - 12). The differences between the two groups are of a magnitude similar to those between the two age groups. The large variation from bird to bird, evident on the basis of age grouping, i s also present in the ATP - grouped data. The data for each of the intermediates and co-factors in-dicates that the standard deviations are of very similar mag-nitude, whether grouped on the basis of age or ATP disappear-ance rate. Concentration of G-6-P was essentially the same for the two groups during the f i r s t 60 minutes but from 60 to 180 min. the Group I concentration rose sharply to 2.1 times the concentration of Group II at 180 min. Fructose-6-phosphate concentration followed a similar pattern. The FDP concentra-tion for Group I birds decreased steadily and almost linearly over the 180 min. but for Group II birds there was a rapid decrease over the i n i t i a l 30 minute period, after which the concentration remained essentially constant. The i n i t i a l con-centrations of DHAP for the two groups were somewhat different, with Group I showing a higher i n i t i a l concentration which gradually decreased over the 3 hours, while Group II showed an i n i t i a l rapid drop over the f i r s t 30 min. and a relatively con-stant concentration over the next 150 min. Group I concentra-tion of GA3P showed a slight i n i t i a l increase followed by a gradual decrease to i t s lowest level at 180 min. whereas the concentration of GA3P for the Group II birds showed a sharp de-CONCENTRATION 1 OF THE GLYCOLYTIC INTERMEDIATES AND CO-FACTORS IN P. SUPERFICIALIS MUSCLE AT VARYING TIMES POST-MORTEM FOR GROUP I I TURKEYS Intermediate Time (min.) Post-mortem  o r C o - f a c t o r 0 15 30 A T P 2 2 .2403 + 1 .6800 5 1 .3803 ± 0 .9074 0 .9152 + 0 .8838 ADP 1 .0448 + 0 .2238 1 .0224 + 0 .2388 0 .9731 T 0 .2055 AMP 0 .3206 + 0 .0485 6 .2953 0 .0871 0 .2886 + 0 .0973 NAD 0 .9054 0 .1949 0 .7999 + 0 .1910 0 .7061 0 .2187 NADH 0 .4571 ± 0 .2691 0 .4330 + 0 .2033 0 .2877 + 0 .0586 CP 0 .3922 + 0 .2369 0 .3523 + 0 .2145 0 .2186 -1. 0 .2029 T o t a l Creatine- 3 3 .8310 + 1 .3630 3 .9154 ± 1 .3630 3 .9049 + 1 .3620 p i 17 .6219 3 .0040 19 .5308 + 2 .9220 19 .5510 + 3 .0080 G-l-P 0 .2979 ± 0 .2900 0 .2692 + 0 .1566 0 .2830 + 0 .1544 G-6-P 2 .2920 ± 1 .0180 2 .1459 + 1 .0380 2 .3880 ± 0 .9249 F-6-P 0 .3267 + 0 .1890 0 .3175 0 .2245 0 .3569 + 0 .2210 FDP 0 .0367 + 0 .0395 0 .0107 + 0 .0052 0 .0069 -1. 0 .0035 DHAP 0 .0235 t 0 .0169 0 .0156 + 0 .0088 0 .0130 + 0 .0024 GA3P 0 .0186 + 0 .0064 0 .0134 + 0 .0047 0 .0114 + 0 .0055 3 PGA 0 .0125 ± 0 .0052 0 .0076 + 0 .0043 0 .0135 + 0 .0081 2 PGA 0 .0092 + 0 .0043 0 .0077 + 0 .0044 0 .0096 ± 0 .0082 PEP 0 .0178 ± 0 .0105 0 .0144 t 0 .0096 0 .0202 ± 0 .0145 Pyruvate 0 .5635 0 .2269 0 .4822 ± 0 .1885 0 .4152 + 0 .1813 L a c t a t e 416 .5578 + 64.7400 409 .2092 ± 81.4900 409 .9011 ± 115.0000 ©C-GP 1 .0623 + i 0 .4245 0 .9105 + 0 .3170 0 .7897 + 0 .2700 Glucose 3 .9271 T 1 .0650 4 .0163 + 0 .9775 4 .2215 0 .9130 Glycogen** 5 .4460 ± 2 .1520 5 .4439 + 1 .9090 5 .4439 + 1 .9090 •'•Concentrations expressed as ^iMoles/g t i s s u e . Continued ^ A b r e v i a t i o n s as g i v e n i n t e x t . •^Concentration expressed as mg/g t i s s u e . ^ C o n c e n t r a t i o n expressed as ;uMoles glucose/g t i s s u e . ^Values are means * standard d e v i a t i o n . Intermediate Time (min.) Post-mortem o r C o - f a c t o r 60 120 180 ATP 0. 3152 + 0 .2039 0.1431 + 0 .1080 0 .0782 + 0 .0874 ADP 0. 8650 ± 0 .2908 0.7751 + 0 .2359 0 .7881 0 .2385 AMP 0. 3496 ± 0 .1586 0.4386 ± 0 .1648 0 .5903 + 0 .2437 NAD 0. 6754 + 0 .2308 0.6626 0 .2287 0 .7868 0 .2695 NADH 0. 2589 0 .0612 0.3398 ± 0 .1652 0 .3650 + 0 .1567 CP 0. 0618 0 .0500 0.0493 ± 0 .0552 0 .0617 0 .0724 T o t a l C r e a t i n e 3. 5867 1 .4720 3.4668 JL 1 .1090 3 .8593 + 1 .4340 ? i 19. 3393 + 1 .9750 19.1442 + 3 .5470 17 .9459 3 .8170 G-l-P 0. 3065 X 0 .2224 0.3067 + 0 .2260 0 .4022 0 .3231 G-6-P 3. 2551 + 1 .6890 4.0551 X 2 .2860 5 .6805 + 3 .2770 F-6-P 0. 4783 + 0 .3435 0.6484 + 0 .4106 0 .8306 ± 0 .5352 FDP 0. 0069 + 0 .0023 0.0054 ± 0 .0029 0 .0055 ± 0 .0030 DHAP 0. 0147 0 .0024 0.0108 ± 0 .0026 0 .0118 + 0 .0031 GA3P 0. 0127 ± 0 .0055 0.0169 + 0 .0107 0 .0139 + 0 .0058 3 PGA 0. 0107 0 .0052 0.0132 + 0 .0056 0 .0117 JL 0 .0063 2 PGA 0. 0097 0 .0060 0.0089 X 0 .0063 0 .0086 + 0 .0055 PEP 0. 0142 0 .0067 0.0171 + 0 .0086 0 .0189 ± 0 .0115 Pyruvate 0. 4160 ± 0 .2473 0.3882 + 0 .2318 0 .3975 - 0 .2320 L a c t a t e 320. 3875 ± 66.5100 396.8778 ± 1. 39.2000 441 .3691 + 72.5400 oc-GP 0. 7412 0 .2816 0.7723 ± 0 .2501 '• 0 .8851 ± 0 .3084 Glucose 4. 0881 + 0 .9103 4.1978 + 0 .9025 4 .2380 1 .0780 Glycogen 5. 5098 2 .1420 5.7024 ± 2 .1220 5 .5715 + 1 .9880 TIME (MIN.) POST-MORTEM F i g u r e 7. Comparisons of c o n c e n t r a t i o n s of some g l y c o l y t i c i n t e r m e d i a t e s i n P. s u p e r f i c i a l i s muscles i n Group I turkeys ( A — — a n d Group II tur k e y s (O O). U J A .018 .013, .008 & I W I H FniW I j • IWIII! I I UJ - J O M r c£-GP 60 120 180 " 60 TIME IvlIN. POST-MORTEM 120 180 Figure 8. Comparisons of concentrations of some glycolytic intermediates in P. superficialis muscles in Group I turkeys (5——AJ and Group II turkeys (O O). to to .0115 .0095j£ .00.75*-.017 .012 =• .^007 .007 r P Y R U V A T E 120 ISO SO TIME mm.) P © S T - ^ O R T E N 120 F i g u r e 9. Comparisons of c o n c e n t r a t i o n s of some g l y c o l y t i c i n t e r m e d i a t e s i n P. s u p e r f I c i a l i s muscles i n Group I turkeys ( A - A ; and Group I I t u r k e y s (O O ) . UJ ZD W </> P < o 3 400 60 C i 5 6.15ff pH 6 20.9r Pi 6.05 5.95 5.85 60 120 TIME (Ml 180 60 L) POST-MORTEM 120 180 Figure 10. Comparisons of concentrations of some glycolytic intermediates in and pH values of P. superficialis muscles in Group I turkeys (A &7 and Group II turkeys (0 O ; . Glycogen concentration Is expressed as uMoles of glucose./g. F i g u r e 11. Comparisons of c o n c e n t r a t i o n s of some g l y c o l y t i c c o - f a c t o r s i n P. s u p e r f i c i a l i s muscles i n Group I tur k e y s (A C) and Group f l turkeys (O O) . Figure 12. Comparisons of concentrations of some glycolytic co-factors in P. superf ic ia l i s muscle in Group I turkeys (A 5) and Group II turkeys (O 0) . Creatine concentration is expressed as mg/g. crease over the i n i t i a l 30 min. then an increase almost to the i n i t i a l level at 120 min. and then a slight decline to 180 min. The concentration of oC-GP for both Groups showed a f a i r l y rapid decrease over the f i r s t hour after which i t rose gradually over the last two hours of measurement. The con-centration of 3PGA and 2PGA for both Groups exhibited consider-able fluctuation over the three hours period. PEP concentra-tion for Group I decreased rapidly while for Group II i t fluctuated considerably for the f i r s t 60 min. The concentra-tion of this intermediate increased slightly over the next two hours for both Groups. Pyruvate concentration dropped for both Groups over the i n i t i a l 30 min. but remained essentially constant for the remainder of the period. Glucose concentra-tion of Group I muscles increased quite sharply between 30 and 120 min. Glycogen concentration, was essentially con-stant for the f i r s t hour, then showed a considerable drop over the last two hours of measurement. Both glucose and glycogen concentration of Group II muscles, showed very l i t t l e increase over the three hours. I n i t i a l ATP concentration was 5.0731>uMoles/g and 2.2403 uMoles/g for Groups I and II respectively, but the con-centration for both Groups was essentially zero at the end of the three hour period. The formation of the two groups on the basis of 7o-ATP at 60 min. accounts for some of the differences in ATP concentration for the groups at varying times. However, i t is evident from the data (Tables IX and X and Figure 11A) that a two-fold difference in i n i t i a l ATP concentration also existed between the groups and was maintained or increased during the f i r s t 60 min. after which the rate of disappearance of ATP from Group I muscles increased and that of Group II muscles de-creased. Both Groups showed a general decrease in ADP con-centration, however, Group I concentration was somewhat higher than that of Group II during the period from 60 to 180 min. post-mortem. The concentration of AMP for both Groups was essen-t i a l l y the same and constant during the f i r s t hour. Group II concentration rose only slightly but Group I concentration i n -creased 5.5 fold over the next 2 hour period. I n i t i a l CP concentration was higher for Group I but the concentration at 180 min. was essentially zero for both Groups. Total creatine concentration showed very l i t t l e net change for either group. Group I NAD concentration decreased sharply over the i n i t i a l 30 min. period, continued to decline during the next 1.5 hours and sharply increased during the last hour. The Group II concentration showed only a slight decrease over the total three hour period. The NADH concentration for both Groups showed a slight net decrease over the three hour period. Inorganic phosphate concentration showed an overall increase over the three hours for Group I but a slight i n i t i a l Increase and then a gradual decrease to the i n i t i a l level for Group II. Kastenschmidt et a l . (1968), categorized pork muscles as "slow-" or "fast-glycolyzing" on the basis of post-mortem pH decline and reported that slow-glycolyzing muscles had a 407. higher i n i t i a l ATP concentration. The results of the present study, clearly indicate that Group I muscles can be classified as "slow-" and Group II as "fast-glycolyzing". This classification is compatible with the data on pH and l a c t i c acid concentrations over the three hour post-mortem period. "Fast-glycolyzing" muscles (Group II) had a lower i n i t i a l ATP concentration, larger percentage of ATP breakdown between 0 and 60 minutes, more rapid i n i t i a l pH drop and a higher l a c t i c acid concentration than did the "slow-glycolyzing" muscles (Group I). These differences between the two groups are sta-t i s t i c a l l y significant at probability levels ranging from 0.0001 to 0.20 (Appendix A - Table XI). From the studies described here, i t i s impossible to determine whether the i n i t i a l ATP level of the "fast-glycolyzing" birds is a reflection of the general in vivo ATP concentration or of some physiological state which makes these birds more susceptible to the stress of slaughter. However, the data clearly establish the existence of considerable variation in post-mortem glycolytic rate among turkeys. Lactic acid and pH for Group I and Group II The data showing l a c t i c acid concentrations and pH values over time (Table IX and X and Figures 10 A and B) do not demonstrate a consistent relationship. This confirms the find-ings reported by Gunther et a l . (1966). Possible sites of post-mortem glycolytic control for Gr° uP 1 a n d ^ r o u p T i " ~ Mass action ratios using the "0" min. data of Groups I and II were calculated as outlined previously. The mass action ratios indicated that for each group, the possible post» mortem glycolytic controlling points are at the reactions cat-alized by hexokinase, phosphofructokinase, aldolase and t r i o -sephosphate isomerase, glyceraldehyde phosphate dehydrogenase and phosphoglycerokinase, and pyruvate kinase (Table XI). Further evidence that the post-mortem glycolytic flux may be controlled at these points might be presented. As was the case for the data of the 15 and 25 week-old birds, the in-termediates prior to the point of action of phosphofructokinase in the cycle, showed an increase in concentration over time, whereas the metabolites after this point were markedly reduced in concentration and generally exhibited a decrease or main-tained a relatively stable level over time. It i s known (e.g. Kastenschmidt et a l . , 1968; Williamson, 1965; Minakami et a l , 1966) that both ATP and G-6-P counteract the activating influences of AMP and P^  on phosphorylase; that phosphofructokinase activity i s influenced by F-6-P, ATP, ADP, AMP, P^; and pyruvate kinase by ATP. It must by accepted that the intermediates and co-factors of the glycolytic cycle may control i t s flux by either activating MASS ACTION RATIOS CALCULATED FROM "0" MINUTE DATA ON GLYCOLYTIC INTERMEDIATES AND CO-FACTORS IN MUSCLES OF GROUP I AND II TURKEYS Re a c t i o n Apparent E q u i l i b r i u m Mass A c t i o n R a t i o s Constant Group I Group II HK 4 X i i r 4 1.92 X 10"1 2.72 X io - i PGM 5.5 X 10~2 12.41 7.69 PGI 0.28 - 0.45 1.32 X io- i 1.43 X 10"! PFK 1-1.1 X 103 2.47 X 10-2 5.23 X l O " 2 A l d o l a s e 0.7-1.3 X l O " 4 6.40 X 10"3 1.09 X l O " 2 PTI 4-5 X 10"2 3.96 X l O " 1 7.92 X i o - i A i d . x PTI 4-6.5 X 10"6 3.20 X l O " 3 8.20 X 10"3 GAPDH x PGK 2-15 X 102 1.09 X i o - i 4.13 X l O " 2 PGM 1-1.8 X i o - i 9.36 X i o - i 7.36 X i o - i Enolase 2.8 - 6.3 1.79 1.94 PK -2-20 X 103 1.59 X 102 1.02 X 102 LDH 1.6 X 104 1.40 X 103 9.76 X 102 A b r e v i a t i o n s as g i v e n i n Tab l e V. or i n h i b i t i n g the v a r i o u s enzymes of the c y c l e . I f a c t i v a t i n g and i n h i b i t i n g f a c t o r s were unbalanced between groups f o r any of s e v e r a l r e a c t i o n s as o u t l i n e d , the mass a c t i o n r a t i o s would be expected to be d i f f e r e n t f o r the two groups. T h i s i s c l e a r l y not the case (Table XI) and t h e r e f o r e the d i f f e r e n c e i n pos t -mortem g l y c o l y s i s between the groups cannot be s a i d t o be mediated through v a r i a b l e r a t e s of r e a c t i o n at the i n h i b i t e d EXPERIMENT IV pH The post-mortem changes i n pH showed c o n s i d e r a b l e v a r i a t i o n from b i r d t o b i r d i n both the 19 and 27 week-old age groups (Appendix A - Table X ) , but were g e n e r a l l y s i m i l a r t o those d e s c r i b e d i n Experiment I, i . e . , a r a p i d i n i t i a l d e c l i n e w i t h a continued g r a d u a l d e c l i n e t o the u l t i m a t e pH or a r a p i d i n i t i a l d e c l i n e f o l l o w e d by a s l i g h t and g r a d u a l i n -crease to the u l t i m a t e pH. The average pH v a l u e s f o r each age group f o l l o w e d p a t t e r n s which were q u i t e s i m i l a r (Table X I I ) . The 19 week-o l d b i r d s had an i n i t i a l pH of 6.27 which d e c l i n e d very r a p i d -l y t o pH 5.89 at 15 min. and then g r a d u a l l y rose t o an u l t i -mate of 5.98 a t 180 min. The 27 week-old b i r d s on the oth e r hand, had an i n i t i a l pH of 6.44 which decreased v e r y r a p i d l y to 6.04 a t 15 min. and then c o n t i n u e d t o d e c l i n e g r a d u a l l y t o an u l t i m a t e of pH 5.95 at 180 min. pH OF P. SUPERFICIAL!S MUSCLE AT VARYING TIMES POST-MORTEM FOR iy AND 27 WEEK-OLD TURKEYS (EXP. IV) Time (min.) Age (wks.) Post-mortem 19 27 0 6.27 ± 0.121 6.44 + 0.32 15 5.89 t 0.22 6.04 + 0.22 30 5.90 + 0.24 5.99 + + 0.20 60 5.93 + 0.22 5.97 0.17 120 5.98 + 0.21 5.96 + 0.13 180 5.98 + 0.20 5.95 + 0.10 ^Values expressed as mean - standard deviation. ATP Adenosine triphosphate concentration was determined at "0" and "60" min. post-mortem to establish the rate of dis-appearance. As in Experiments I and II i n i t i a l ATP concentra-tion showed great v a r i a b i l i t y among birds in each age group. The average i n i t i a l ATP concentration was 5.4129 ± 2.2900 and 4.4858 i 2.6400 juMoles/g for 19 and 27 week-old birds respec-tively (Table XIII). ATP concentration at 60 minutes as a per-cent of i n i t i a l ATP concentration (%-ATP) was 53.59 ± 31.47% and 55.20 * 19.05% for the 19 and 27 week-old birds respectively, COMPARISON ATP CONCENTRATION IN P. SUPERFICIALIS MUSCLES AT "0" AND "60" MINUTES POST-MORTEM " FOR 19 AND 27 WEEK-OLD TURKEYS (EXP. IV). Bird No. Age Time (min.) Post-mortem. 0 60 (60/0)xl00 20 19 9.44031 8.87671 94.032 21 19 4.2975 1.5499 36.07 22 19 4.2270 1.2681 30.00 23 19 6.7632 5.9178 87.50 24 19 4.5088 2.5362 56.25 25 19 3.2407 0.5636 17.39 x 3 5.4129*2.2900 3.4521*3.2580 53.59*31/47 30 27 3.0294 2.2544 74.42 31 27 8.7358 6.6928 76.61 32 27 6.6928 2.3953 35.79 33 27 1.8317 .5636 30.77 34 27 3.3488 1.8317 54.70 35 27 3.2760 1.9292 58.89 x 3 4.4858*2.6400 2.6110*2.1020 55.20*19.05 overall 4.9490*2.4060 3.0320*2.6510 54.40*24.82 Values are averages of duplicate analysis expressed as juMoles/g tissue. Values expressed as 60 minute concentration as a percent of i n i t i a l concentration (%-ATP). Values are expressed as means * standard deviations. Rigor mortis measurement. To relate the physical changes that take place to the chemical changes, an attempt was made to assess the contraction of the muscle post-mortem. To achieve a measure of this physi-cal parameter the instrument previously described was used. Although not designed to allow the loading and unloading cycle on the muscle s t r i p s , nor to al l o w the q u a n t i t a t i v e measure-ment of t e n s i o n developed over time i n the s t r i p s h e l d a t con-s t a n t l e n g t h , the attachment of a constant l o a d on the s t r i p d u r i n g the post-mortem p e r i o d was p o s s i b l e . By measuring the muscle s t r i p l e n g t h under constant l o a d , i t was f e l t t h a t an approximation of the t e n s i o n development p a t t e r n c o u l d be a c h i e v e d . In p r e l i m i n a r y experiments i t was found t h a t the a-mount of a p p l i e d weight t h a t would a l l o w the muscle s t r i p t o c o n t r a c t and shor t e n was i n s u f f i c i e n t t o cause l e n g t h e n i n g of the s t r i p a f t e r i t had passed i n t o r i g o r , even up t o 3 6 hours post-mortem. Conversely, the amount of a p p l i e d weight s u f f i -c i e n t t o cause r e l e n g t h e n i n g of the muscle s t r i p p o s t - r i g o r , was too g r e a t t o a l l o w c o n t r a c t i o n and s h o r t e n i n g of the muscle s t r i p p r e - r i g o r . In o r d e r to ac h i e v e an estimate of the c o n t r a c t i o n p a t t e r n , t h e r e f o r e , t h r e e muscle s t r i p s were e x c i s e d from the P. s u p e r f i c i a l i s immediately p o s t - e x s a n g u i n a t i o n . The s t r i p s were e x c i s e d i n order from the a n t e r i o r to the p o s t e r i o r l o c a -t i o n and were 1 0 x 1 . 5 x 1 . 5 cm bef o r e e x c i s i o n . The s t r i p s were then allowed t o c o n t r a c t f r e e l y and the weights a t t a c h e d a f t e r the completion of c o n t r a c t i o n as p r e v i o u s l y d e s c r i b e d . An example of the c o n t r a c t i o n p a t t e r n i s shown i n F i g u r e 1 3 . The l e n g t h measurements were made by V e r n i e r c a l i -pers and the data expressed as S = l - L / L 0 (Davey e_t a l . 1 9 7 0 ) . S d e f i n e s the degree of s h o r t e n i n g (+ ve) or s t r e t c h i n g (- v e ) , L Q i s the i n i t i a l l e n g t h of the s t r i p and L Is the l e n g t h at the CO 120 TIME 180 2 4 0 ) POST-MORTEI 3.00 360 F i g u r e 13. T y p i c a l c o n t r a c t i o n p a t t e r n s of P. s u p e r f i c i a l i s muscle s t r i o s . time of measurement. The t y p i c a l p a t t e r n ( F i g . 13) obt a i n e d i n the pre-sent study i s ve r y s i m i l a r t o the i s o m e t r i c t e n s i o n p a t t e r n d e s c r i b e d by Jungk e t a l . (1970). They d e s c r i b e d an I n i t i a l phase t o maximum t e n s i o n development and a subsequent decrease i n the r e l a t i v e t e n s i o n . T h i s t e n s i o n development p r i o r t o the onset of r i g o r i s equated wi t h the tendency f o r muscle to shorte n w h i l e being r e s t r a i n e d by attachment t o the c a r c a s s . In the presen t study the parameter of importance was taken t o be the time a t which c o n t r a c t i o n was maximum i . e . , no f u r t h e r s h o r t e n i n g took p l a c e . Table XIV shows the time t o maximum c o n t r a c t i o n f o r each of the t h r e e muscle s t r i p s from each i n d i v i d u a l b i r d . The o v e r a l l average time t o maximum c o n t r a c t i o n was 130, 128.2 and 125 minutes f o r s t r i p s 1, 2 and 3 r e s p e c t i v e l y . I t has been e s t a b l i s h e d (e.g. Jungk et a l . 1970) tha t e x c i s i o n of s t r i p s from the muscle induces some s h o r t e n i n g . The amount of s h o r t e n i n g induced by e x c i s i o n can be determined e a s i l y by comparison of the l e n g t h of the s t r i p on the c a r c a s s w i t h t h a t immediately a f t e r e x c i s i o n . Smith et a l . (1969), r e -po r t e d s h o r t e n i n g due to e x c i s i o n t o be 10.4% and Jungk et a l . (1970) r e p o r t e d a s h o r t e n i n g of 107». The data of Experiment IV i n d i c a t e d t h a t the average amount of s h o r t e n i n g due to e x c i -s i o n was 8.7%. Jungk et a l . (1970), r e p o r t e d the average time f o r tu r k e y b r e a s t muscle s t r i p s to achieve maximum t e n s i o n t o be 3.85 * 0.19 hours. T-I Ma et a l . (1971), r e p o r t e d c o n s i d e r a b l e variability in the time course of rigor mortis in turkey muscle strips. Their data showed a range of from 25 to 391 min. re-quired to complete the decrease in extensibility. The data from the present study is also highly variable with a range of 60 to 210 minutes required for the muscle strips to attain max-imum contraction. TABLE XXV TIMES TO MAXIMUM CONTRACTION FOR INDIVIDUAL 19 AND 27 WEEK-OLD BIRDS (EXP. IV). Bird No. Time (min.) to Maximum Contraction Strip 1 Strip 2 Strip 3 20 19 130 150 150 21 19 105 105 105 22 19 110 84 96 23 19 165 165 165 24 19 90 90 90 25 19 90 75 60 x 1 115*28.64 111.5* 37.25 111*39.34 30 27 105 105 105 31 27 210 210 195 32 27 180 180 180 33 27 105 105 90 34 27 135 135 135 35 27 135 135 135 ^ 1 4 5 * 4 2 . 0 7 1 4 5 * 4 2 . 0 7 1 4 0 * 4 0 . 9 9 y overall Z1 130*37.72 128*41.73 125*41.19 Values are expressed as means - standard deviations. The post-mortem c a t a b o l i s m o f ATP i s known t o be a s s o c i a t e d w i t h the post-mortem p h y s i c a l changes of muscle (e.g. Newbold, 1966; Jungk et a l . , 1970; Khan, 1971). Sybesma (1969), i n d i c a t e d t h a t i n three c l a s s e s of r i g o r , the muscles t h a t were i n complete r i g o r showed the lowest ATP conc e n t r a -t i o n , those a t the onset of r i g o r had i n t e r m e d i a t e and those without any s t i f f n e s s had the h i g h e s t ATP c o n c e n t r a t i o n . T a b l e X V J . c o n t a i n s the c o r r e l a t i o n c o e f f i c i e n t s ( r ) between ATP c o n c e n t r a t i o n and time t o maximum c o n t r a c t i o n . When the data f o r the 19 and 27 week-old b i r d s was combined, the ATP c o n c e n t r a t i o n a t 0 min. post-mortem showed the h i g h e s t c o r r e l a t i o n w i t h the time t o maximum c o n t r a c t i o n . When the data f o r each age group was c o n s i d e r e d s e p a r a t e l y however, time t o maximum c o n t r a c t i o n was most s t r o n g l y c o r r e l a t e d w i t h %-ATP f o r 19 week-old b i r d s and w i t h i n i t i a l ATP f o r the 27 week-old b i r d s . The data c l e a r l y support the r e l a t i o n s h i p be-tween post-mortem ATP c a t a b o l i s m and p h y s i c a l changes i n muscle. Regrouping of Data on B a s i s of ATP Disappearance Rates The data f o r the 12 b i r d s were regrouped on the b a s i s of ATP disappearance r a t e s as d e s c r i b e d f o r Experiments I and II. The ATP c o n c e n t r a t i o n at 60 min. as a percent o f i n i t i a l R E L A T I O N S H I P B E T W E E N A T P C O N C E N T R A T I O N A N D T I M E T O M A X I M U M M U S C L E C O N T R A C T I O N ( E X P . I V ) . Simple C o r r e l a t i o n C o e f f i c i e n t s ( r ) S t r i p 1 S t r i p 2 S t r i p 3 A T P - 0 1 A T P - 6 0 2 A T P - % 3 A T P - 0 1 A T P - 6 0 2 A T P - % 3 <n= 1 2 ) ( n - 1 2 ) (n= 1 2 ) 0 . 6 8 * 0 . 7 4 * * 0 . 7 5 * * 0 . 5 7 n.s. 0 . 6 8 * 0 . 6 8 * 0 . 4 3 n.s. 0 . 5 6 n.s. 0 . 6 0 * (n= 1 0 ) (n= 1 0 ) <n= 1 0 ) 0 . 4 7 n.s. 0 . 5 8 n.s. 0 . 6 2 n.s. 0 . 5 7 n.s. 0 . 7 3 * 0 . 7 4 * 0 . 6 5 * 0 . 8 0 * * 0 . 8 3 * * a t " 0 " minutes post-mortem. at " 6 0 " minutes post-mortem. at " 6 0 " minutes as a percent of A T P at " 0 " minutes post-mortem. 0 . 0 1 0 . 0 5 • • S i g n i f i c a n t a t P * S i g n i f i c a n t a t P n.s. Not s i g n i f i c a n t a t P 0 . 0 5 A T P c o n c e n t r a t i o n i n d i c a t e d two g e n e r a l groups w i t h a % - A T P range of 5 5 t o 9 4 f o r Group I and 1 7 to 3 7 Group I I . Group I , i n c l u d e d b i r d s numbered 2 0 , 2 3 , 2 4 , 3 0 , 3 1 , 3 4 and 3 5 had a mean % - A T P of 7 1 . 7 7 * 1 5 . 6 6 and a mean i n i t i a l A T P c o n c e n t r a t i o n of 5 . 5 8 6 0 ± 2 . 7 1 4 0 ^Moles/g. Group I I i n c l u d e d b i r d s numbered 2 1 , 2 2 , 2 5 , 3 2 and 3 3 had a mean % - A T P of 3 0 . 0 7 ± 7 . 5 8 and a mean i n i t i a l A T P c o n c e n t r a t i o n of 4 . 0 5 7 9 ± 1 . 7 7 9 0 uMoles/g. Group I muscles had mean c o n t r a c t i o n times of 1 3 8 . 6 -3 9 . 5 5 , 1 4 1 . 4 ± 3 9 . 5 5 and 1 3 9 . 3 ± 3 5 . 4 1 min. f o r muscle s t r i p s 1 , 2 and 3 respectively and an overall mean of 140.01 min. Group II had mean contraction time of 118.0 ± 35.46, 109.8 ± 41.38 and 106.2 * 44.58 min. for muscle strips 1, 2 and 3 respec-tively and an overall mean of 111.73 rnin. These data are consis-tent with the previously quoted literature, in that muscles with faster glycolytic rates ( i . e . Group II) achieved rigor at an earlier time. The regrouping served to reduce the v a r i a b i l i t y of the ATP concentration data only slightly but showed no re-duction in the varia b i l i t y in the data for time required to a-chieve maximum contraction. Regrouping of the data on the basis of ATP disappearance does not Improve the correlation between ATP disappearance and time to maximum contraction. The regrouped data show higher correlations between i n i t i a l ATP and contraction time than between 70-ATP at 60 min. and time to maximum contraction. The average time to maximum contraction appears to be linearly related to percent ATP (Figure 14). The relation-ship i s considerably improved (Table XV) i f the birds number-ed 31 and 32 (Figure 14) are not considered. These two birds deviate severely from the relationship presented by the other 10 birds and although no explanation i s readily apparent for this deviation the remainder of the data suggest a relationship worthy of consideration. The average time to maximum contrac-tion for Group I shows a v a r i a b i l i t y reduced from 38.1 to 35.0 min. and for Group II from 40.5 to 19.0 min., when these birds © H O < I-o o O b. I GROUP II 190 170 150 130 ^ 110 •z, 90 70 GROUP I 03I 0 32 O O O A 20 40 60 ATP {%) 80 100 Figure 14. Plot of maximum contraction time vs. %-ATP (ATP cone, at 60 min, as a percent of ATP cone, at 0 min.) . (45-100% Group I ; 0-45% Group II). are o m i tted from the d a t a . The c o r r e l a t i o n between 7o-ATP and time t o maximum c o n t r a c t i o n i s improved s l i g h t l y f o r Group I and q u i t e markedly f o r Group II. I t appears from the present study that the time r e -q u i r e d f o r muscle s t r i p s t o reach maximum c o n t r a c t i o n i s r e l a t e d to some exte n t t o the post-mortem m e t a b o l i c pathway, but t h a t t h i s r e l a t i o n s h i p i s not p a r t i c u l a r l y s t r o n g . The c o n c e n t r a t i o n of g l y c o l y t i c i n t e r m e d i a t e s and co-f a c t o r s i n b r e a s t muscle of f i v e 15 week-old and f i v e 25 week-o l d White Cannon torn turkeys was measured at s i x times po s t -mortem. pH was a l s o measured over t h i s time p e r i o d . The data showed l a r g e b i r d - t o - b i r d v a r i a b i l i t y i n both age groups. I t was concluded t h a t d i f f e r e n t r a t e s of p o s t -mortem g l y c o l y s i s occur i n t u r k e y b r e a s t muscle. However, the d i f f e r e n c e i n r a t e s i s not c o r r e l a t e d w i t h age. The p a t t e r n s of change i n c o n c e n t r a t i o n of the i n -t e r m e d i a t e s and c o - f a c t o r s suggest t h a t post-mortem g l y c o l y s i s i n g e n e r a l , i n t u r k e y muscle i s s u b j e c t to some c o n t r o l at v a r i o u s r e a c t i o n p o i n t s . Mass a c t i o n r a t i o s as an i n d i c a t i o n of r e a c t i o n e q u i l i b r i u m c o n s t a n t s , suggest t h a t c o n t r o l l i n g p o i n t s might occur a t the r e a c t i o n steps c a t a l y z e d by hexo-k i n a s e , phosphofructo k i n a s e , a l d o l a s e and t r i o s p h o s p h a t e i s o -merase, g l y c e r a l d e h y d e phosphate dehydrogenase and phosphogly-c e r o k i n a s e and pyruvate k i n a s e . Phosphofructo k i n a s e appears t o be the s i t e of primary c o n t r o l . When the data were regrouped on the b a s i s of the d i s -appearance of ATP over time post-mortem two d i s t i n c t groups be-came e v i d e n t . The l a r g e b i r d - t o - b i r d v a r i a b i l i t y c o n t r i b u t e d t o the l a r g e v a r i a t i o n evident f o r the two g roupings. The two groups c o u l d be c a t e g o r i z e d as " f a s t - " and " s l o w - g l y c o l y z i n g " on the b a s i s of ATP c a t a b o l i s m , pH and l a c t i c a c i d accumulation. The data of the two groups Indicated that post-mortem metabolism can be controlled at a number of sites but that the different rates of glycolysis can not be attributed to d i f -ferent extents of glycolytic control. An additional six 19 week-old and six 27 week-old White Cannon torn turkey breast muscles were analyzed for ATP at "0" and "60" minutes post-mortem. pH during the three hour post-mortem period was also measured. The time course of rigor for three muscle strips from each bird was measured. The pattern of muscle strip length over time post-mortem very closely resembled a pattern of tension development in muscle strips over time post-mortem. On the combined data of the 19 and 27 week-old birds, time to maximum contraction showed the highest correlation (r = .68 - .75) with the i n i t i a l ATP concentration, whereas for the 19 week-old birds the highest correlation was with ATP con-centration at "60" minutes as a percent of "0" minute concentra-tion. For the 27 week-old bird muscles the highest correlation was between i n i t i a l ATP concentration and time to maximum con-traction. When the data for the 19 and 27 week-old birds were regrouped on the basis of ATP disappearance, a "slow-" and "fast-^ glycolyzing" group became evident. The group with the higher i n i t i a l ATP concentration, had a larger percentage of the i n i t i a l ATP remaining at "60" minutes and longer: times for muscle strips to achieve maximum contraction. Adam, H. 1963. Adenosine-5 -diphosphate and adenosine-5 -monophosphate, in Bergmeyer, H.U. (ed.) Methods of Enzymatic Analysis, p.573. Academic Press, New York. 1965. Bendall, J.R. 1966. 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Sayre, R.N. 1970. Chicken myofibril fragmentation in relation to factors influencing tenderness. J . Food Sci. 35:7. Sayre, R.N., Briskey, E.J. and Hoekstra, W.G. 1963a. Comparison-of muscle characteristics and post-mortem glycolysis in three breeds of swine. J. Animal Sci. 22:9012. Sayre, R.N., Briskey, E.J. and Hoekstra, W.G. 1963b. Porcine muscle glycogen structure and i t s association with other muscle properties. Proc. Soc. Exptl. B i o l . Med. 112:164. Schmidt, G.R., Cassens, R.G. and Briskey, E.J. 1968. Develop-ment of an isotonic and isometric rigorometer. J. Food Sci. 33:239. Schmidt, G.R. and B r i s k e y , E . J . 1970. Phosphocreatine and n u c l e o t i d e changes i n p i g l o n g i s s i m u s muscle d u r i n g the development of r i g o r m o r t i s under c o n t r o l l e d e n v i r o n -mental c o n d i t i o n s . J . Food S c i . 35(5):568. S c h o l t y s s e k , S. and K l o s e , A.A. 1967. Sources of v a r i a b i l i t y i n t u r k e y tenderness. 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Food S c i . 36(1):125. Tomlinson, N., Geiger, S.E. and D o l l i n g e r , E. 1965. C h a l k i n e s s i n H a l i b u t i n r e l a t i o n t o muscle pH and p r o t e i n denatur-a t i o n . J . F i s h . Res. Bd. Canada. 22:653. Welbourne, J.L., H a r r i n g t o n , R.B. and Stadelman, W.J. 1968. R e l a t i o n s h i p s among shear v a l u e s , sarcomere l e n g t h s and c o o l i n g procedures i n t u r k e y s . J . Food S c i . 33^5):450. W e l l s , G.H. and Dawson, L.E. 1966. Tenderness and j u i c i n e s s of f r e e z e - d r i e d c h i c k e n meat as r e l a t e d to m a t u r i t y of b i r d s . P o u l t r y S c i . 45(5):1004. W i l l i a m s o n , J.R. 1965. G l y c o l y t i c c o n t r o l mechanisms. I . I n h i b i t i o n of g l y c o l y s i s by a c e t a t e and pyruvate i n the i s o l a t e d p e r f u s e d r a t h e a r t . J . B i o l . Chem. 240(6):2308. APPENDIX A MOISTURE CONTENT AS PERCENT OF WET WEIGHT FOR 25 WEEK-OLD BIRDS (EXP. II). Bird No. % Moisture 10 11 12 13 14 73.7J 75.0 74.3 73.7 73.7 x 74.3 Average of duplicate determinations. TABLE II COMPARISON OF METHOD OF MEASURING pH (EXP. III) . Time p.m.*- pH (min.) Bird 15 Bird 16 Probe Slurry Probe Slurry 0 1 6.35 7.10 6.49 15 7.64 6.31 6.81 6.45 30 7.50 6.21 6.75 6.48 60 6.73 6.22 6.65 6.41 120 6.25 6.20 6.32 6.13 180 6.17 5.99 6.21 6.13 Timing was started three minutes after exsanguination. EXPERIMENT I. Bird No. Age (Wks-Days) Weight (lbs.) 2 15 5 14.25 3 15 6 14.00 4 15 6 14.00 5 16 0 12.50 6 16 0 14.00 ave. 15 6 13.75 TABLE IV THE AGE AND WEIGHT OF TURKEYS AT TIME OF SLAUGHTER FOR EXPERIMENT II. Bird No. Age Weight (Wks - Days) (lbs.) 10 24 6 22.75 11 24 6 27.25 12 25 0 19.25 13 25 0 23.25 14 25 1 22.25 ave. ~T5 0~ 22.95 EXPERIMENT IV. Bird No. Age Weight (Wks - Days) (lbs.) 20 18 3 18.75 21 18 4 19.25 22 18 6 19.75 23 19 3 18.25 24 19 4 18.25 25 19 5 18.50 ave. " T T 0 ' 18.79 30 27 2 20.00 31 27 3 26.50 32 27 3 27.25 33 27 4 31.00 34 27 4 23.50 35 27 5 22.25 ave. 2/ 6 25.08 THE TIME COURSE OF pH POST-MORTEM (EXP. I) Bird No. Time (min.) Post-mortem 0 15 30 60 120 180 2 6.01 6.19 6.28 6.24 6.03 6.02 3 5.92 5.78 5.85 5.90 5.94 5.94 4 6.26 5.87 5.87 5.86 5.82 5.77 5 6.05 6.05 6.05 5.97 5.97 5.97 6 6.32 6.06 6.08 6.06 5.98 5.97 ^Timing was started 10 minutes after exsanguination. TABLE VII THE TIME COURSE OF pH POST -MORTEM (EXP. II) * Bird No. Time (min.) Post-mortem1 0 15 30 60 120 180 10 6.17 5.98 5.99 5.96 6.00 6.00 11 5.93 5.80 5.86 5.94 5.96 5.96 12 6.25 5.80 5.85 5.90 5.93 5.94 13 6.26 5.72 5.76 5.83 5.86 5.87 14 6.23 5.86 5.96 6.02 6.03 6.03 ^Timing was started 10 minutes after exsanguination. CONCENTRATION1 OF THE GLYCOLYTIC INTERMEDIATES AND CO-FACTORS IN P. SUPERFICIAL!S MUSCLE AT VARYING TIMES POST-MORTEM FOR 15 WEEK-OLD TURKEYS (EXP. i). Intermediate Bird No. Time (min.) Post-mortem  or Co-factor 0 1 5 30 60 120 180 ATP2 2 3.16405 3.7034 3 1.5052 0.8601 4 1.3938 0.6959 5 0.7774 1.1177 6 7.2862 6.4331 ADP 2 0.9123 0.4293 3 1.1767 1.2836 4 1.2877 1.2877 5 1.1298 0.8070 6 0.8383 0.9725 AMP 2 0.2976 0.5005 3 0.3505 0.4045 4 0.3517 0.3787 5 0.2308 0.1629 6 0.1769 0.1354 NAD 2 0.9643 1.0045 3 1.2029 1.1468 4 1.0045 0.8941 5 0.9975 0.7305 6 1.0125 0.9474 NADH 2 0.5182 0.6357 3 0.4827 0.4838 4 0.4475 0.2832 5 0.9672 0.8092 ,6 0.2079 0.4875 3.5236 1.9416 0.2876 0.0719 0.4301 0.2150 0.2150 0.0359 0.4175 0.0719 0.0360 0.0719 0.2479 0.2526 0.0000 0.0000 6.1038 5.4102 0.8323 0.2759 0.6171 1.0732 0.4293 0.4025 1.2302 1.0162 0.8558 0.8291 1.0463 1.0731 0.9390 1.0195 0.8877 0.6725 0.6456 0.8608 1.0162 1.1766 1.0697 0.9627 0.3111 0.2706 0.2841 0.2570 0.3505 0.5932 0.5797 0.7415 0.3517 0.3516 0.4057 0.4869 0.1629 0.2037 0.3530 0.8140 0.0539 0.1618 1.6179 1.5102 1.0045 1.0196 0.S438 0.9041 1.0969 1.0161 1.0346 1.1468 0.7082 0.7635 0.6580 0.7232 0.6851 0.7305 0.7002 1.0378 0.9624 0.9223 1.0025 0.9274 0.5989 0.4223 0.3647 0.3309 0.3160 0.2586 0.2488 0.2496 0.2217 0.2530 0.2249 0.3065 0.3075 0.3350 0.2625 0.3857 0.2410 0.4240 0.4653 0.3507 Intermediate Bird No. Time (min.) Post-mortem or Co-factor 0 15 30 60 120 180 CP Total Creatine-G-l-P G-6-P 2 0.2227 0.5938 0.2227 0.0000 0.0742 0.0000 3 0.0740 0.0740 0.0740 0.0370 0.0370 0.148.0 4 0.5034 0.5753 0.5753 0.0371 0.0370 0.0000 5 0.4026 0.5772 0.2188 0.0745 0.0000 0.0000 6 3.7638 6.8309 3.4408 0.8602 0.5735 0.2867 2 3.9676 4.4254 5.3410 4.5780 5.0358 5.6462 3 2.5942 3.5098 3.2046 2.5942 3.0520 3.2046 4 3.6744 3.8275 3.3682 3.1539 3.2611 2.6793 5 1.9200 1.8586 1.9047 1.4439 1.8739 2.1658 6 1.5410 1.4391 1.3734 1.0682 1.0072 1.2513 2 13.9385 13.7949 13.5298 13.2537 13.8059 13.2537 3 16.4235 16.1474 18.0802 17.2629 16.0149 16.0149 4 16.6996 20.4328 17.8041 17.8041 15.1976 13.8832 5 20.0131 19.4719 18.7650 19.1958 18.2238 16.4235 6 4.7448 13.3862 12.7014 12.6462 12.6462 29.6772 2 0.4854 0.3426 0.2855 0.3426 0.4568 0.6282 3 0.2562 0.2562 0.3985 0.5408 0.5123 0.5977 4 0.4283 0.4597 0.3712 0.4854 0.3997 0.7995 5 0.0000 0.0573 0.0573 0.0000 0.0573 0.0000 6 0.1199 0.3019 0.0589 0.0589 0.2078 0.1187 2 3.4983 3.7041 3.8584 5.3503 8.6428 10.0833 3 2.4612 2.4869 3.0765 4.5122 5.4352 7.6400 4 3.1896 3.5754 3.4468 5.1960 6.1734 8.8485 5 0.6192 0.9804 1.2126 0.9030 1.0320 2.2188 6 2.5893 2.2632 1.7990 2.4966 8.3421 11.3801 Intermediate or Co-factor Bird No. Time (min.) Post-mortem 0 15 30 60 120 180 F-6-P 2 0.4155 0.5713 0.3116 0.8310 1.4023 1.4542 3 0.3624 0.3106 0.4141 0.7247 1.0094 1.4494 4 0.6752 0.7531 0.7531 1.0387 1.1426 1.4022 5 0.1563 0.2605 0.2084 0.2084 0.2866 0.4429 6 0.4688 0.4154 0.2588 0.2071 1.1391 1.9667 FDP 2 0.0710 0.0710 0.0761 0.0837 0.0343 0.0101 3 0.0189 0.0126 0.0076 0.0064 0.0064 0.0051 4 0.0095 0.0037 0.0037 0.0113 0.0056 0.0075 5 0.0113 0.0076 0.0019 0.0057 0.0000 0.0076 6 0.0870 0.0939 0.1108 0.0751 0.0732 0.0057 DHAP 2 0.0602 0.0552 0.0678 0.0201 0.0151 0.0000 3 0.0187 0.0200 0.0150 0.0175 0.0100 0.0125 4 0.0200 0.0075 0.0113 0.0150 0.0075 0.0075 5 0.0075 0.0075 0.0111 0.0150 0.0113 0.0150 6 0.0375 0.0336 0.0485 0.0373 0.0224 0.0150 GA3P 2 0.0202 0.0177 0.0177 0.0104 0.0050 0.0000 3 0.0187 0.0176 0.0151 0.0101 0.0151 0.0151 4 0.0150 0.0075 0.0075 0.0075 0.0075 0.0150 5 0.0264 0.0191 0.0019 0.0226 0.0376 0.0226 6 0.0151 0.0150 0.0150 0.0113 0.0113 0.0000 3 PGA 2 0.0000 0.0140 0.0169 0.0028 0.0168 0.0168 3 0.0084 0.0111 0.0084 0.0084 0.0111 0.0056 4 0.0169 0.0037 0.0252 0.0140 0.0196 0.0140 5 0.0094 0.0019 0.0019 0.0019 0.0057 0.0075 6 0.0141 0.0094 0.0038 - 0.0038 -Intermediate or Co-factor Bird No. Time (min.) Post-mortem 0 15 30 60 120 180 2 PGA 2 0.0028 0.0194 0.0028 0.0055 0.0000 0.0111 3 0.0083 0.0028 0.0028 0.0139 0.0000 0.0028 4 0.0056 0.0074 0.0167 0.0139 0.0139 0.0111 5 0.0075 0.0019 0.0037 0.0018 0.0056 0.0037 6 0.0065 0.0130 - 0.0018 0.0038 -PEP 2 0.0138 0.0055 0.0165 0.0055 0.0055 0.0055 3 0.0137 0.0137 0.0109 0.0109 0.0082 0.0109 4 0.0183 0.0019 0.0467 0.0193 0.0330 0.0412 5 0.0019 0.0037 0.0074 0.0074 0.0110 0.0092 6 0.0093 0.0128 0.0055 0.0037 0.0019 -Pyruvate 2 0.3334 0.2077 0.0820 0.1312 0.1312 0.1530 3 0.6752 0.6425 0.6643 0.6507 0.6530 0.6425 4 0.5681 0.5571 0.5684 0.7487 0.6367 0.7105 5 0.1840 0.1620 0.1656 0.1436 0.1454 0.1546 6 0.2308 0.1060 0.0110 0.0000 0.1462 -Lactate 2 339.1830 365.2737 281.7828 333.9648 354.8376 313.0920 3 416.0928 299.0667 603.3346 369.2824 301.6673 421.2940 4 294.8283 534.8655 333.9648 260.9100 657.4930 524.4291 5 434.5288 395.2614 397.8790 251.2920 285.3212 418.8200 6 119.3996 127.6080 106.3519 151.1865 180.3812 114.6932 OC-GP 2 0.6321 0.5531 0.5794 0.4741 0.7901 0.7375 3 0.8400 0.7875 0.8400 0.6300 0.7613 0.8400 4 1.0009 0.8955 0.8428 0.8428 0.8955 0.9482 5 1.8761 1.4800 1.2155 1.2369 1.1626 1.4269 6 1.1140 1.0792 0.8933 0.6831 0.7357 0.8407 Intermediate or Co-factor Bird No. Time (min.) Post-mortem 0 15 30 60 120 . 180 Glucose 2 3.9518 3.8665 3.8490 4.4351 4.8902 5.2885 3 3.8539 4.1373 4.3306 4.4207 4.4490 4.2223 4 4.4067 4.8047 4.8331 4.6057 4.7763 4.7194 5 2.0824 2.2250 2.4247 2.2820 2.4532 2.1394 6 3.1051 2.8470 1.6559 3.4882 3.9616 3.9032 Glycogen4 2 5.3063 6.0643 6.0643 6.0643 6.0643 6.0643 3 6.0844 6.0844 6.0844 6.0844 5.3238 6.0844 4 6.4859 6.4859 6.4859 6.1043 6.8674 6.4859 5 5.3587 6.1242 6.1242 6.1242 6.8898 6.8898 6 6.1441 6.4855 5.5938 6.0842 5.3237 3.0421 ^Concentrations expressed as yuMoles/g tissue. 2Abreviations as given in text. •^Concentration expressed as mg/g tissue. ^Concentration expressed as >uMoles glucose/g tissue. ^Values are means of duplicates. CONCENTRATION1 OF THE GLYCOLYTIC INTERMEDIATES AND CO-FACTORS IN P. SUPERFICIALIS MUSCLE AT VARYING TIMES POST-MORTEM FOR 25 WEEK OLD TURKEYS (EXP.u ; . Intermediate or Co-factor Bird No, Time (min.) Post-mortem 0 15 30 60 120 180 10 6.29495 5.0217 4.3144 3.3242 0.5658 0.1415 11 3.5478 2.5544 2.4125 2.6963 0.5676 0.1419 12 3.8900 2.2633 1.9804 0.5658 0.2829 0.0000 13 4.8119 2.7584 2.1219 0.5658 0.1415 0.1415 14 1.0632 0.5866 0.2933 0.2200 0.1833 0.2200 10 1.1453 1.0907 1.1998 1.3088 1.3361 1.0089 11 0.9848 1.0942 1.1216 1.1763 1.0395 0.7933 12 1.0907 1.0635 1.0907 1.0089 0.8726 0.8999 13 0.9271 0.9816 0.9544 1.0635 0.9817 0.7908 14 0.6565 0.7112 0.6292 0.3557 0.3557 0.3283 10 0.1650 0.1925 0.1925 0.2200 1.1548 1.5672 11 0.1655 0.1655 0.1655 0.2206 1.6548 1.4342 12 0.3299 0.2613 0.3712 0.4537 0.5912 0.5637 . 13 0.3024 0.2887 0.3299 0.3299 0.5362 0.7699 14 0.3585 0.2758 0.1655 0.1655 0.1655 0.1655 10 0.7093 0.7552 0.7144 0.6327 0.6123 0.6021 11 0.6554 0.6861 0.6963 0.6554 0.6963 0.6963 12 0.7807 0.6531 0.6735 0.6531 0.6531 0.6939 13 0.6990 0.7144 0.6531 0.5715 0.6123 0.7246 14 0.7476 0.6605 0.4195 0.3175 0.3175 0.3943 10 0.3491 0.5296 0.3547 0.4267 0.1705 0.3515 11 0.1189 0.0620 0.1396 0.2217 0.0000 0.1364 12 0.3204 0.3915 0.3282 0.3026 0.5494 0.3192 13 0.3189 0.3875 0.3461 0.2495 0.2000 0.2608 14 0.2056 0.2426 0.2065 0.1546 0.5530 0.6684 ATP^  ADP AMP NAD NADH Intermediate or Co-factor Bird No. Time (min.) Post :-mortem 0 15 30 60 120 180 CP 10 1.9733 1.1694 0.4385 0.1462 0.1462 0.0000 11 0.8798 0.7332 0.4399 0.4399 0.1466 0.1466 12 0.2923 0.1462 0.0000 0.0000 0.0000 0.0000 13 0.7780 0.4385 0.2923 0.1462 0.1462 0.1462 14 0.3027 0.3027 0.1514 0.0757 0.0757 0.0757 Total Creatine3 10 6.2240 6.0684 6.5352 6.3796 6.2240 6.6840 11 6.0879 6.2440 6.0779 6.0879 6.2240 5.9318 12 4.5124 5.6016 4.8236 4.9792 4.8236 5.4460 13 5.4460 5.2604 5.7572 5.2904 4.6680 5.6016 14 4.8391 3.4342 4.2708 4.0586 3.1220 4.0586 Pi 10 13.8059 14.4244 17.1856 18.6325 16.2910 13.8059 11 17.6384 15.8771 19.2731 16.0149 15.1755 14.1483 12 18.0802 18.4889 19.4608 19.4608 19.1847 19.3946 13 12.9776 17.9367 17.6605 19.3946 21.5372 17.1193 14 21.5372 24.7071 25.5354 22.9178 24.7071 24.8396 G-l-P 10 0.2322 0.1742 0.1161 0.0000 0.1161 0.1161 11 0.3494 0.1165 0.2329 0.3494 0.4658 0.3494 12 0.8125 0.3482 0.2322 0.2322 0.2322 0.3482 13 0.1741 0.3772 0.4643 0.4643 0.5804 0.6094 14 0.1165 0.1165 0.1747 0.1165 0.0582 0.0582 G-6-P 10 5.4899 5.0194 4.1305 2.8757 7.4245 10.4570 11 3.1472 2.8324 2.7800 3.6192 10.2283 10.9101 12 2.9280 2.0914 2.8300 3.3463 5.0194 5.4376 13 3.0325 2.7973 3.0848 3.9998 5.4115 8.6270 14 1.5213 0.9442 1.6784 1.5735 1.2588 1.3113 Intermediate Bird No. Time (min.) Post-mortem or Co-factor 120 180 0 15 30 60 F-6-P 10 0.6334 0.6334 0.6334 0 .4223 0.8466 1 .6891 11 0.4236 0.3177 0.2118 0 .3117 1.4827 1 .5886 12 0.2111 0.2111 0.2111 0 .2111 0.5279 0 .5279 13 0.3431 0.2639 0.3959 0 .4751 0.8182 1 .0026 14 0.2118 0.1059 0.1589 0 .2118 0.1059 0 .1589 FDP 10 0.0052 0.0052 0.0077 0 .0052 0.0052 0 .0052 11 0.0879 0.0336 0.0297 0 .0155 0.0103 0 .0052 12 0.1095 0.0180 0.0103 0 .0052 0.0077 0 .0052 13 0.0554 0.0142 0.0103 0 .0077 0.0052 0 .0000 14 0.0155 0.0078 0.0078 0 .0052 0.0078 0 .0078 DHAP 10 0.0153 0.0153 0.0102 0 .0153 0.0153 0 .0102 11 0.0154 0.0102 0.0102 0 .0180 0.0154 0 .0102 12 0.0306 0.0153 0.0153 0 .0153 0.0102 0 .0102 13 0.0537 0.0306 0.0153 0 .0102 0.0102 0 .0102 14 0.0102 0.0128 0.0102 0 .0154 0.0154 0 .0154 GA3P 10 0.0154 0.0154 0.0205 0 .0180 0.0154 0 .0103 11 0.0154 0.0129 0.0103 0 .0154 0.0103 0 .0051 12 0.0103 0.0103 0.0154 0 .0103 0.0154 0 .0103 13 0.0154 0.0103 0.0154 0 .0103 0.0103 0 .0051 14 0.0258 0.0155 0.0129 0 .0155 0.0154 0 .0154 3 PGA 10 0.0114 0.0171 0.0057 0 .0114 0.0114 0 .0171 11 0.0115 0.0057 0.0115 0 .0115 0.0115 0 .0057 12 0.0057 0.0057 0.0114 0 .0114 0.0171 ,0 .0171 13 0.0171 0.0114 0.0171 0 .0114 0.0086 0 .0057 14 0.0172 0.0115 0.0172 0 .0172 0.0172 0 .0201 Intermediate or Co-factor Bird No. Time (min.) Post-mortem 0 15 30 60 120 180 2PGA 10 0.0142 0.0113 0.0113 0.0113 0.0113 0.0170 11 0.0114 0.0114 0.0114 0.0057 0.0057 0.0057 12 0.0057 0.0113 0.0057 0.0057 0.0113 0.0113 13 0.0113 0.0113 0.0057 0.0057 0.0057 0.0057 14 0.0170 0.0114 0.0227 0.0170 0.0170 0.0170 PEP 10 0.0281 0.0253 0.0112 0.0112 0.0168 0.0168 11 0.0113 0.0113 0.0113 0.0113 0.0113 0.0113 12 0.0168 0.0224 0.0224 0.0112 0.0168 0.0168 13 0.0337 0.0224 0.0112 0.0112 0.0168 0.0168 14 0.0225 0.0225 0.0225 0*0253 0.0169 0.0187 Pyruvate 10 0.6814 0.3574 0.2178 0.1676 0.2039 0.1229 11 0.6496 0.4564 0.2100 0.1792 0.2800 0.2072 12 0.7819 0.6702 0.4329 0.4636 0.4468 0.3742 13 0.4245 0.3910 0.3016 0.2932 0.3240 0.3184 14 0.7476 0.4704 0.3584 0.1960 0.1232 0.1848 Lactate 10 296.9910 365.9353 365.9353 326.1597 323.5080 360.6319 11 191.5362 202.1771 202.1771 170.2544 180.8953 202.1771 12 429.5762 445.3362 486.7628 424.6229 403.9096 471.2278 13 434.8797 429.5762 307.5978 296.9910 418.9694 493.2172 14 489.4414 351.1497 329.8679 319.2270 313.9066 319.2270 Ot-GP 10 0.8166 0.6124 0.6890 0.6124 0.5104 0.5614 11 0.4197 0.5371 0.3223 0.2954 0.2148 0.3223 12 0.8166 0.6124 0.4083 0.4083 0.4083 0.4849 13 0.7145 0.6635 0.6124 0.6124 0.6635 0.7656 14 1.1259 1.0239 0.8191 0.7167 0.7423 0.8447 Intermediate or Co-factor Bird No. Time (min.) Post-mortem 0 15 30 60 120 180 Glucose 10 3.6984 3.1205 3.6984 3.2939 4.8542 4.5652 11 3.8842 4.0001 4.2320 4.1161 5.2176 5.3915 12 5.0853 4.6230 4.5074 4.6230 4.9121 5.1432 13 3.4960 3.6405 4.3339 4.0450 4.0739 4.3918 14 4.6381 4.6670 4.8990 4.5511 4.5221 4.8120 Glycogen^ 10 7.7550 7.7550 8.5305 7.7550 6.2040 6.2040 11 8.1690 7.7800 7.7800 8.5579 8.5579 7.3910 12 8.5305 7.7550 7.7550 8.5305 8.5305 7.7550 13 2.3265 3.1020 3.1020 2.3265 3.1020 3.1020 14 3.8900 3.1120 3.1120 3.8900 3.5010 3.1120 Concentrations expressed asjuMoles/g tissue. ^Abreviations as given in text. ^Concentration expressed as mg/g tissue. ^Concentration expressed as AxMoles glucose/g tissue. ^Values are means of duplicates. pH OF P . S U P E R F I C I A L I S MUSCLE AT VARYING TIMES POST-MORTEM FOR 19 AND 27 WEEK-OLD TURKEYS ( E X P . I V ) . B i r d N o . Age (wks) T i m e ( m i n . ) P o s t - m o r t e m . l 0 15 30 60 120 180 20 19 6 . 1 8 6 . 11 6 .11 6 . 1 0 6 . 0 7 6 . 0 5 21 19 6 . 3 1 5 . 7 6 5 . 7 3 5 . 7 7 5 . 8 0 5 . 8 0 22 19 6 . 0 8 5 . 7 5 5 . 7 5 5 . 7 9 5 . 8 4 5 . 8 5 23 19 6 . 4 3 6 . 2 3 6 . 3 0 6 . 3 1 6 . 3 4 6 . 3 3 24 19 6 . 3 1 5 . 7 5 5 . 7 6 5 . 8 6 5 . 9 8 6 . 0 2 25 19 6 . 2 6 5 . 7 5 5 . 7 5 5 . 7 8 5 . 8 3 5 . 8 5 30 27 6 . 3 5 5 . 8 8 5 . 8 1 5 . 8 1 5 . 8 3 5 . 8 5 31 27 6 . 7 9 6 . 3 0 6 . 2 3 6 . 2 1 6 . 1 3 6 . 0 7 32 27 6 . 4 9 5 . 8 5 5 . 8 5 5 . 8 5 5 . 8 4 5 . 8 4 33 27 5 . 9 4 5 . 8 5 5 . 8 5 5 . 8 6 5 . 8 9 5 . 9 1 34 27 6 . 7 6 6 . 3 3 6 . 2 5 6 . 1 6 6 . 0 9 6 . 0 6 35 27 6 . 2 9 6 . 0 2 5 . 9 5 5 . 9 2 5 . 9 5 5 . 9 6 T i m i n g was s t a r t e d 15 m i n u t e s a f t e r e x s a n g u i n a t i o n . CALCULATED AND SELECTED TABLED t VALUES FOR CERTAIN PARAMETERS FOR EXPERIMENT I AND I I . Parameter t c a l c . t (0.05) t (0.01) 15 wk. v s . 25 wk. NAD 0 min. 1.276 2.306 3.355 15 min. 3.586 2.306 3.355 30 min. 2.642 2.306 3.355 60 min. 3.674 2.306 3.355 120 min. 2.671 2.306 3.355 180 min. 3.607 2.306 3.355 1,5 wk. v s . 25 wk. T o t a l  C r e a t i n e 0 min. 4.625 2.306 3.355 15 min. 3.027 2.306 3.355 30 min. 3.189 2.306 3.355 60 min. 3.717 2.306 3.355 120 min. 2.418 2.306 3.355 180 min. 2.999 2.306 3.355 Group I v s . Group I I I n i t i a l ATP 3.060 2.306 3.355 %-ATP 7.499 2.306 3.355 pH a t 15 min. 1.839 2.306 3.355 L a c t i c a c i d a t 30 min. 2.332 2.306 3.355 APPENDIX B TIME CMINJ POST-yORTEW? Figure 1. The pH of P. superficialis muscle at varying times post-mortem for 15 weelc-old turkeys. (O OBird 2; £ A Bird 3; • OBird 4 ;0 OBird 5; £> -A Bird 6). pH 60 90 TIME MIN. 120 150 POST-MORTEM 180 F i g u r e 2. The pH of P. s u p e r f i c i a l i s muscle a t v a r y i n g times p o s t -mortem f o r 25 week-old t u r k e y s . (O O B i r d 10; A & B i r d 11; • O B i r d 12; 0 - O B i r d 13; A -aBird 14). PGM ++ 2 PGA Mg j;Mn Enolase » r + + hg ADP K+ PEP ATP NADH r V / V J DP Pyruvate ^ — NAD -> L a c t a t e PK LDH F i g u r e 3. G l y c o l y t i c c y c l e shoving I n t e r m e d i a t e s , c o - f a c t o r s and enzymes.' 

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