- Email: [email protected]
Temperature and pH Changes in Poultry Breast Muscles at Slaughter1
DIETHYLSTILBESTROL AND GROWTH PATTERNS Entenman, C, F. W. Lorenz and I. L. Chaikoff, 1938. The endocrine control of lipide metabolism in the bird. I. The effects of pregnant mare serum upon the blood and liver lipides of the domestic fowl. J. Biol. Chem. 126: 133-139. Herbert, B. A., and C. C. Brunson, 1957. The effects of diethylstilbestrol, testosterone, thiouracil and thyroprotein on the chemical composition of broiler carcasses. Poultry Sci. 36: 898-904. Lauffer, R. G., 1957. The effect of caponizing and estrogen treatments on the performance of New Hampshire cockerels. Poultry Sci. 36: 376-377. Lorenz, F. W., 1945a. The fattening action of orally administered synthetic estrogens as compared with diethylstilbestrol pellet implants. Poultry Sci. 24: 91-92. Lorenz, F. W., 1945b. The influence of diethylstilbes-
765
trol on fat deposition and meat quality in chickens. Poultry Sci. 24: 128-134. Lorenz, F. W., 1954. Effects of estrogens on domestic fowl and applications in the poultry industry. Vitamins and Hormones, 12: 235-275. Lorenz, F. W., I. L. Chaikoff and C. Entenman, 1938. The endocrine control of lipide metabolism in the bird. II. The effects of estrin on the blood lipides of the immature domestic fowl. J. Biol. Chem. 126: 763-769. Snedecor, G. W., 1956. Statistical Methods, Iowa State College Press, Ames, Iowa. Sturkie, P. D., 1946. The effect of estrogens upon the meat quality of old cocks and hens. Poultry Sci. 25: 356-368. Thayer, R. H., R. G. Jaap and R. Penquite, 1945. Fattening chickens by feeding estrogens. Poultry Sci. 24: 483-495.
Temperature and p H Changes in Poultry Breast Muscles at Slaughter1 J. W. D O D G E 2 AND F. E. P E T E R S
Purdue University, Lafayette, Indiana (Received for publication September 21, 1959)
D
U R I N G a study of factors affecting tenderness in poultry meat, an investigation was made of p H and temperature changes in the breast muscles of birds during and after slaughter. p H has been investigated in beef and pork by BateSmith and Bendall (1949), and Scaife (1955). However, little or no work has been done on poultry. p H should give an indication of rates and extensiveness of glycolysis in the tissue and would therefore be a consideration in a study of postmortem tenderization (de Fremery and Pool, 1958). I n studies of contraction on rabbit and h u m a n muscle Marson et al. (1938) found a slight increase in p H after contraction. This is in apparent conflict 1
Journal Paper No. 1497 of the Purdue Agricultural Experiment Station. 2 Present Address: Nichols, Inc., Exeter, New Hampshire.
with Bate-Smith and Bendall as well as Scaife. A preliminary note on this work was published b y Peters and Dodge, (1959). APPARATUS EMPLOYED A copper—constantan thermocouple was used to determine the temperature within the muscle. The thermocouple was connected to a Honeywell recording potentiometer adjusted to record every 30 seconds. Beckman p H needle electrodes 40,470 and 40,249 were adapted to a Leeds N o r t h r u p 7,662 p H meter. By the use of this apparatus p H could be observed continually before, during, and after slaughter. EXPERIMENTAL PROCEDURE All birds were procured from the Purdue University Research Farm. Types
766
J. W. DODGE AND F. E. PETERS
used in the study included mature White Leghorn hens, Hoosier White meat-type stags, mature Broad Breasted Bronze and Broad White turkeys, and mature Pilgrim geese. These were brought directly from the farm to the laboratory in crates. At the laboratory each bird was suspended on a wooden horse with its feet, wings, and neck secured. Sufficient time was then allowed for the bird to quiet. A thermocouple was inserted into the pectoralis major muscle approximately onehalf inch below the skin surface. The electrodes were also inserted into the pectoralis major at this time. Both the thermocouples and the electrodes were kept in place by sewing the stems to the skin. Again the bird was allowed to become quiet to the point where the pH and temperature became steady. The throat was cut. Temperature was recorded automatically every 30 seconds and pH was recorded every 30 seconds for the first five minutes, and every two to five minutes thereafter, depending on the rate of change. Readings were continued until the pH had dropped to around 5.8. Preliminary experiments were conducted by anesthetizing the birds with Nembutal, injected intravenously. Because of inconsistencies in the pH and temperature this procedure was discarded.
RESULTS
The observations made on pH and temperature are averaged in Table 1. It will be noticed that in every type of bird studied, a rise in both pH and temperature was observed during the slaughter and early post-mortem period. The rise in pH cannot be atrributed to temperature differences affecting readings on the pH meter as this machine was continually adjusted for temperature changes. A typical curve for the pH readings over time is shown in Figure 1. The reasoning behind the initial rise is difficult to pin point. It may be due to the liberation of considerable amounts of creatine as creatine phosphate is broken down, or it may be due to changes in the tissue buffering system. Definite plateaus are noticed as pH decreases from its maximum value. This could be due to isoelectric points of the tissue proteins,— or alterations in the tissue component buffering capacity. The observations of Marson et dl. (1938), that the pH of muscle is increased on exercise would appear to be confirmed in the work. Figure 2 shows a typical temperature curve over time. The temperature of the carcass would be expected to rise during the tetany at slaughter, as the blood or cooling system of the carcass is being
TABLE 1.—Mean temperature and pH rises during and after slaughter Type bird
Number birds
Chickens Stags Hens
Initial (range) pH
Mean (range) PH
Initial (range) temperature °F.
Mean (range) temperature rise °F.
7.24(7.15-7.28) 7.21(7.15-7.25)
.19 (.00-.30) .16 (.05-.25)
107.8 (107.0-108.0) 107.6 (106.8-108.0)
.79( .00-1.30) .43 ( .00-1.50)
Turkeys Toms Hens
2 3
7.23(7.20-7.25) 7.18(7.15-7.20)
.07 (.00-.15) .34(.10-.50)
107.25(107.0-107.5) 107.20(107.0-107.4)
3.00(2.50-3.50) 1.50(1.00-2.25)
Geese Gander Geese
3 4
7.20(7.20) 7.24(7.20-7.25)
.17(.10-.25) .12 (.05-.20)
107.0 (106.5-107.5) 107.0 (107.0)
.78 ( .60-1.00) .44( .00- .75)
767
CHANGES IN MUSCLES AT SLAUGHTER
30
60
90
120
150
Minutes After Slaughter
FIG. 1. A typical pH curve following slaughter in chickens.
drained away. Both pH and temperature readings varied between birds as would be expected. The males in each type of bird studied showed a higher average temperature rise at slaughter whereas the males only in the case of chickens and geese displayed a higher pH rise. The reports by Bate-Smith and Bendall (1949) as well as Scaife (1955) on the pH changes occurring in beef and pork muscle after slaughter make no mention Op
112
•
110 108 106 104 102
SUMMARY The study consisted of temperature and pH measurements of 26 birds before, during, and after slaughter. Chickens, geese, and turkeys were studied. Both pH and temperature were found to rise at slaughter. These affects were noticed more in the males of each species than the females. REFERENCES
•
-5
of the pH rise that was observed in these studies. This may be due to the initial pH being defined (Bate-Smith and Bendall, 1949) as "the pH of the muscle within 5 minutes of slaughter." In this study it was found that in most cases the pH had already begun to decline 5 minutes after slaughter.
0
10
20
30
•40
Minutes After Slaughter
FIG. 2. Typical temperature response of turkey breast muscle after slaughter.
Bate-Smith, E. C, and J. R. Bendall, 1949. Factors determining the time course of rigor mortis. J. Physiology, 110: 47-65. De Fremery, D., and M. F. Pool, 1958. Biochemical studies with chicken muscle as related to rigormortis and tenderization. Poultry Sci. 38: 1198.
768
J. W. DODGE AND F. E. PETERS
Marson, G. L., O. S. Orth and K. E. Lemmer, 1938. pH changes in rabbit and human striated muscle after contraction. Amer. J. Physiol. 121: 311-24. Peters, F. E., and J. W. Dodge, 1959. Changes in
pH temperature in poultry breast muscles at slaughter. Nature, 183: 68F. Scaife, J. F., 1955. Variation of ultimate pH within pork muscles. J. Sci. Food Agric. 6: 46F.
Genetics of Wheaten Plumage in the Fowl ELLIOT KIMBALL
Clinton Experimental Farm, Clinton, Connecticut (Received for publication September 21, 1959)
A
as in Black-breasted Red. The Wheaten female is so named because of nonstippled red-wheat coloration in adult plumage, black appearing only in rectrices and remiges. Breast plumage in the Wheaten hen is creamy wheaten, not salmon as in the Black-breasted Red female with dorsolateral stippled pattern and brown coloration. Chicks of the cross cited were white in ground color, displaying a mid-dorsal chestnut stripe, but complete absence of black in the down (see Figure 1). The sexes were identical in respect to down pattern and color. Juveniles developed striking sexual dichromatism, a circumstance persisting on assumption of adult plumage. Hybrid males were superficially blackred, but revealed white undercolor, like their sire. Delicate nonblack margination OBSERVATIONS of breast feathers was frequent, approxiWheaten Game Bantam d* X Black- mately 65 percent of adult males exhibitbreasted Red Game Bantam 9 . The sire of ing red in breast feather margins on close this mating was superficially indistin- inspection. guishable in phenotype from the BlackHybrid females were light in coloration, breasted Red variety. Closer observation showing a modified wheaten ground with discovered white undercolor, or fluff, as superposed dorso-lateral pallid stippling contrasted with charcoal gray in the and creamy salmon breast, associated standard Black-breasted Red. Further, with white undercolor. The phenotype study of Wheaten sires mated to Wheaten was that of an intermediate between fedams showed their progeny are nonstriped male-type pattern and coloration of the white in the down, not wild type striped two parental varieties.
MONG breeds or varieties of domes>• tic fowl exhibiting white down are Wheaten Game Bantam, Salmon Faverolle, and Black-breasted Red Cubalaya. Genetic analysis to be reported here indicates that the principal heritable factor responsible for white down and adult plumage coloration is the same in all members of the group. Since review of the literature uncovered no study of the gene, a contribution on the subject seems justifiable. The term "black-breasted red" has acquired definite phenotypic significance, as in Black-breasted Red Game and its bantam counterpart, and is a misnomer when applied to the variety of Cubalaya under scrutiny. Wherefore, Wheaten Cubalaya will be used in this report to designate the so-called Black-breasted Red Cubalaya.
765
trol on fat deposition and meat quality in chickens. Poultry Sci. 24: 128-134. Lorenz, F. W., 1954. Effects of estrogens on domestic fowl and applications in the poultry industry. Vitamins and Hormones, 12: 235-275. Lorenz, F. W., I. L. Chaikoff and C. Entenman, 1938. The endocrine control of lipide metabolism in the bird. II. The effects of estrin on the blood lipides of the immature domestic fowl. J. Biol. Chem. 126: 763-769. Snedecor, G. W., 1956. Statistical Methods, Iowa State College Press, Ames, Iowa. Sturkie, P. D., 1946. The effect of estrogens upon the meat quality of old cocks and hens. Poultry Sci. 25: 356-368. Thayer, R. H., R. G. Jaap and R. Penquite, 1945. Fattening chickens by feeding estrogens. Poultry Sci. 24: 483-495.
Temperature and p H Changes in Poultry Breast Muscles at Slaughter1 J. W. D O D G E 2 AND F. E. P E T E R S
Purdue University, Lafayette, Indiana (Received for publication September 21, 1959)
D
U R I N G a study of factors affecting tenderness in poultry meat, an investigation was made of p H and temperature changes in the breast muscles of birds during and after slaughter. p H has been investigated in beef and pork by BateSmith and Bendall (1949), and Scaife (1955). However, little or no work has been done on poultry. p H should give an indication of rates and extensiveness of glycolysis in the tissue and would therefore be a consideration in a study of postmortem tenderization (de Fremery and Pool, 1958). I n studies of contraction on rabbit and h u m a n muscle Marson et al. (1938) found a slight increase in p H after contraction. This is in apparent conflict 1
Journal Paper No. 1497 of the Purdue Agricultural Experiment Station. 2 Present Address: Nichols, Inc., Exeter, New Hampshire.
with Bate-Smith and Bendall as well as Scaife. A preliminary note on this work was published b y Peters and Dodge, (1959). APPARATUS EMPLOYED A copper—constantan thermocouple was used to determine the temperature within the muscle. The thermocouple was connected to a Honeywell recording potentiometer adjusted to record every 30 seconds. Beckman p H needle electrodes 40,470 and 40,249 were adapted to a Leeds N o r t h r u p 7,662 p H meter. By the use of this apparatus p H could be observed continually before, during, and after slaughter. EXPERIMENTAL PROCEDURE All birds were procured from the Purdue University Research Farm. Types
766
J. W. DODGE AND F. E. PETERS
used in the study included mature White Leghorn hens, Hoosier White meat-type stags, mature Broad Breasted Bronze and Broad White turkeys, and mature Pilgrim geese. These were brought directly from the farm to the laboratory in crates. At the laboratory each bird was suspended on a wooden horse with its feet, wings, and neck secured. Sufficient time was then allowed for the bird to quiet. A thermocouple was inserted into the pectoralis major muscle approximately onehalf inch below the skin surface. The electrodes were also inserted into the pectoralis major at this time. Both the thermocouples and the electrodes were kept in place by sewing the stems to the skin. Again the bird was allowed to become quiet to the point where the pH and temperature became steady. The throat was cut. Temperature was recorded automatically every 30 seconds and pH was recorded every 30 seconds for the first five minutes, and every two to five minutes thereafter, depending on the rate of change. Readings were continued until the pH had dropped to around 5.8. Preliminary experiments were conducted by anesthetizing the birds with Nembutal, injected intravenously. Because of inconsistencies in the pH and temperature this procedure was discarded.
RESULTS
The observations made on pH and temperature are averaged in Table 1. It will be noticed that in every type of bird studied, a rise in both pH and temperature was observed during the slaughter and early post-mortem period. The rise in pH cannot be atrributed to temperature differences affecting readings on the pH meter as this machine was continually adjusted for temperature changes. A typical curve for the pH readings over time is shown in Figure 1. The reasoning behind the initial rise is difficult to pin point. It may be due to the liberation of considerable amounts of creatine as creatine phosphate is broken down, or it may be due to changes in the tissue buffering system. Definite plateaus are noticed as pH decreases from its maximum value. This could be due to isoelectric points of the tissue proteins,— or alterations in the tissue component buffering capacity. The observations of Marson et dl. (1938), that the pH of muscle is increased on exercise would appear to be confirmed in the work. Figure 2 shows a typical temperature curve over time. The temperature of the carcass would be expected to rise during the tetany at slaughter, as the blood or cooling system of the carcass is being
TABLE 1.—Mean temperature and pH rises during and after slaughter Type bird
Number birds
Chickens Stags Hens
Initial (range) pH
Mean (range) PH
Initial (range) temperature °F.
Mean (range) temperature rise °F.
7.24(7.15-7.28) 7.21(7.15-7.25)
.19 (.00-.30) .16 (.05-.25)
107.8 (107.0-108.0) 107.6 (106.8-108.0)
.79( .00-1.30) .43 ( .00-1.50)
Turkeys Toms Hens
2 3
7.23(7.20-7.25) 7.18(7.15-7.20)
.07 (.00-.15) .34(.10-.50)
107.25(107.0-107.5) 107.20(107.0-107.4)
3.00(2.50-3.50) 1.50(1.00-2.25)
Geese Gander Geese
3 4
7.20(7.20) 7.24(7.20-7.25)
.17(.10-.25) .12 (.05-.20)
107.0 (106.5-107.5) 107.0 (107.0)
.78 ( .60-1.00) .44( .00- .75)
767
CHANGES IN MUSCLES AT SLAUGHTER
30
60
90
120
150
Minutes After Slaughter
FIG. 1. A typical pH curve following slaughter in chickens.
drained away. Both pH and temperature readings varied between birds as would be expected. The males in each type of bird studied showed a higher average temperature rise at slaughter whereas the males only in the case of chickens and geese displayed a higher pH rise. The reports by Bate-Smith and Bendall (1949) as well as Scaife (1955) on the pH changes occurring in beef and pork muscle after slaughter make no mention Op
112
•
110 108 106 104 102
SUMMARY The study consisted of temperature and pH measurements of 26 birds before, during, and after slaughter. Chickens, geese, and turkeys were studied. Both pH and temperature were found to rise at slaughter. These affects were noticed more in the males of each species than the females. REFERENCES
•
-5
of the pH rise that was observed in these studies. This may be due to the initial pH being defined (Bate-Smith and Bendall, 1949) as "the pH of the muscle within 5 minutes of slaughter." In this study it was found that in most cases the pH had already begun to decline 5 minutes after slaughter.
0
10
20
30
•40
Minutes After Slaughter
FIG. 2. Typical temperature response of turkey breast muscle after slaughter.
Bate-Smith, E. C, and J. R. Bendall, 1949. Factors determining the time course of rigor mortis. J. Physiology, 110: 47-65. De Fremery, D., and M. F. Pool, 1958. Biochemical studies with chicken muscle as related to rigormortis and tenderization. Poultry Sci. 38: 1198.
768
J. W. DODGE AND F. E. PETERS
Marson, G. L., O. S. Orth and K. E. Lemmer, 1938. pH changes in rabbit and human striated muscle after contraction. Amer. J. Physiol. 121: 311-24. Peters, F. E., and J. W. Dodge, 1959. Changes in
pH temperature in poultry breast muscles at slaughter. Nature, 183: 68F. Scaife, J. F., 1955. Variation of ultimate pH within pork muscles. J. Sci. Food Agric. 6: 46F.
Genetics of Wheaten Plumage in the Fowl ELLIOT KIMBALL
Clinton Experimental Farm, Clinton, Connecticut (Received for publication September 21, 1959)
A
as in Black-breasted Red. The Wheaten female is so named because of nonstippled red-wheat coloration in adult plumage, black appearing only in rectrices and remiges. Breast plumage in the Wheaten hen is creamy wheaten, not salmon as in the Black-breasted Red female with dorsolateral stippled pattern and brown coloration. Chicks of the cross cited were white in ground color, displaying a mid-dorsal chestnut stripe, but complete absence of black in the down (see Figure 1). The sexes were identical in respect to down pattern and color. Juveniles developed striking sexual dichromatism, a circumstance persisting on assumption of adult plumage. Hybrid males were superficially blackred, but revealed white undercolor, like their sire. Delicate nonblack margination OBSERVATIONS of breast feathers was frequent, approxiWheaten Game Bantam d* X Black- mately 65 percent of adult males exhibitbreasted Red Game Bantam 9 . The sire of ing red in breast feather margins on close this mating was superficially indistin- inspection. guishable in phenotype from the BlackHybrid females were light in coloration, breasted Red variety. Closer observation showing a modified wheaten ground with discovered white undercolor, or fluff, as superposed dorso-lateral pallid stippling contrasted with charcoal gray in the and creamy salmon breast, associated standard Black-breasted Red. Further, with white undercolor. The phenotype study of Wheaten sires mated to Wheaten was that of an intermediate between fedams showed their progeny are nonstriped male-type pattern and coloration of the white in the down, not wild type striped two parental varieties.
MONG breeds or varieties of domes>• tic fowl exhibiting white down are Wheaten Game Bantam, Salmon Faverolle, and Black-breasted Red Cubalaya. Genetic analysis to be reported here indicates that the principal heritable factor responsible for white down and adult plumage coloration is the same in all members of the group. Since review of the literature uncovered no study of the gene, a contribution on the subject seems justifiable. The term "black-breasted red" has acquired definite phenotypic significance, as in Black-breasted Red Game and its bantam counterpart, and is a misnomer when applied to the variety of Cubalaya under scrutiny. Wherefore, Wheaten Cubalaya will be used in this report to designate the so-called Black-breasted Red Cubalaya.