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Mercuric Chloride Effects on the Activities of Some Hepatic Enzymes in Chicks1
Mercuric Chloride Effects on the Activities of Some Hepatic Enzymes in Chicks1 W. E. DONALDSON AND J. P. THAXTON
Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27607 (Received for publication January 14, 1975)
ABSTRACT Three groups of 6 male chicks each were fed a commercial diet and were given drinking water which contained either 0, 150 or 300 \x.g. of mercury/ml. as mercuric chloride from hatching to 3 weeks of age. The chicks were killed, the livers were removed and weighed, and the activities of selected enzymes were measured in the 800 x gav supernatant fractions of the liver homogenates. Liver weights were depressed from control values in chicks receiving 300 p.p.m. mercury but not in chicks receiving 150 p.p.m. Fatty acid synthetase specific activity was depressed by both levels of added mercury, but microsomal fatty acid elongation was depressed only by 300 p.p.m. of mercury. Both levels of added mercury stimulated acid phosphatase specific activity. The specific activities of cytochrome c oxidase, glucose-6phosphatase and 6-phosphogluconate dehydrogenase were unaffected by added mercury. The data support the hypothesis that mercury administration does not result in generalized hepatotoxicity. POULTRY SCIENCE 54: 1613-1616, 1975
INTRODUCTION
M
ERCURY compounds interact with sulfhydryl groups and have been used to inhibit the activities of a number of enzymes in vitrojhowever, there are few reports of in vivo effects of mercury on enzyme activities. Miller et al. (1969) reported the inhibition of kidney alkaline phosphatase by injections of mercuric chloride into chicks. Reductions of liver content of the microsomal cytochromes P-450 by b5 as well as the activities of aminopyrine demethylase and UDP glucuronyltransferase in rats by subcutaneous administration of methylmercury hydroxide were reported by Lucier et al. (1971/72). Singhal et al. (1974) reported increases of activity of several gluconeogenic enzymes in liver and kidney of rats treated with methylmercury. Dieter (1974) showed that dietary mercuric chloride reduced the plasma cholinesterase and increased the plasma lactate dehydrogenase activities in quail. The purpose of this investigation was to
1. Paper No. 4572 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, North Carolina.
determine the effects of a 3 week exposure to mercuric chloride in the drinking water of chicks on the hepatic activities of fatty acid synthetase, the microsomal system of fatty acid elongation, cytochrome c oxidase, acid phosphatase, glucose-6-phosphatase and 6-phosphogluconate dehydrogenase. The latter four enzymes are commonly used as subcellular markers for mitochondria, lysosomes, microsomes and cytosol, respectively (Donaldson et al., 1970; Mason and Donaldson, 1972). The physiological effects of exposure of chicks to mercury in the drinking water have been reported elsewhere (Parkhurst and Thaxton, 1973; Thaxton and Parkhurst, 1973). METHODS Male chicks were maintained in electrically-heated cages from day-old to 3 weeks of age, and a commercially prepared diet was available ad libitum throughout the experiment. The treatments consisted of adding 0, 150 or 300 ixg. of mercury/ml. of drinking water as mercuric chloride, and the drinking water was available ad libitum. At 3 weeks, 6 chicks were selected at random from each treatment and killed by cervical dislocation.
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W. E. DONALDSON AND J. P. THAXTON
The livers were removed immediately and placed in cold 0.25 M sucrose. Each liver was minced, rinsed and homogenized in a Potter-Elvejhem tissue grinder with a Teflon pestle. After filtering through a nylon net, the homogenates were centrifuged for 10 min. at 800 x g av . The pellet was discarded and the supernatant fractions were used in all assays. All steps were carried out at 0-5°. Protein was determined in each fraction by the biuret method of Cleland and Slater (1953). Fatty acid synthetase and the microsomal system of fatty acid elongation activities were measured as described previously (Donaldson et al., 1970; Mason and Donaldson, 1972). The above assays were carried out with freshly prepared fractions. All other assays were carried out with frozen fractions which were freshly thawed. Cytochrome c oxidase was assayed by the procedure of Smith (1955). Acid phosphatase and glucose-6-phosphatase were assayed according to De Duve et al. (1955). The procedure of Glock and McLean (1953) was used to assay 6-phosphogluconate dehydrogenase. Prior to the assays for cytochrome c oxidase, acid phosphatase and glucose-6-phosphatase the fractions, in 1 ml. aliquots, were sonicated for 1 min. in the presence of 1 raM reduced glutathione. All assays were linear with respect to time and protein concentration. Enzyme activities were expressed in units as
TABLE 1.—Effects
follows: fatty acid synthetase and microsomal elongation of fatty acids, 1 unit = 1 (jimole malonyl-CoA incorporated into long-chain fatty acids/min. at 25°; cytochrome c oxidase, 1 unit = 1 ixmole cytochrome c oxidized/min. at 25°; acid phosphatase, 1 unit = 1 (xmole (3-glycerol phosphate hydrolyzed/min. at 37°; glucose6-phosphatase, 1 unit = 1 ^mole glucose-6phosphate hydrolyzed/min. at 37°; 6phosphogluconate dehydrogenase, 1 unit = 1 (jimole 6-phosphogluconate oxidized/min. at 25°. RESULTS AND DISCUSSION The experimental results are shown in Table 1. Liver weight was significantly depressed (P < 0.01) by 300 p.p.m. mercury in the drinking water, but 150 p.p.m. was without effect as compared with controls. Both levels of mercury depressed fatty acid synthetase activity below control values (P < 0.01), but only the 300 p.p.m. level of mercury significantly depressed (P < 0.05) the activity of the microsomal system of fatty acid elongation. Acid phosphatase activity was stimulated above control values by both 150 p.p.m. (P < 0.05) and 300 p.p.m. (P < 0.01) of mercury. The activities of cytochrome c oxidase, glucose-6-phosphatase and 6-phosphogluconate dehydrogenase in
of mercury in the drinking water on liver weight and the activities of various liver enzymes Enzyme activity, mUnits/mg. protein 1
drinking water, ug./ml. 0 150 300
Liver weight, g-
Fatty acid synthetase
Microsomal elongation
2.24 ± 0.23 10.5 ± 0.4 0.23 ± 0.03 9.3 ± 1.6 1.15 ± 0 . 1 1 * * 0.15 ± 0 . 0 1 7.5 ± 0.4** 0.93 ±0.15** 0.13 ± 0.01*
Cytochrome c oxidase
Acid phosphatase
475 ± 54 461 ± 27 476 ± 54
16 ± 1 . 8 23 ± 0.2* 30 ± 0.2**
6-phosphoGlucose-6 gluconate phosphatase dehydrogenase 66 ± 11 87 ± 5 76 ± 3
3.4 ± 0.3 3.8 ± 0 . 1 3.4 ± 0.2
•Each value represents the mean ± S.E.M. of 6 livers. Each assay was carried out in duplicate. Means of the mercury treated chicks were compared with the means of the control chicks by t tests. The symbols * and ** indicate that the means were statistically significantly different from control means, P < 0.05 and P < 0.01, respectively. Enzyme units are defined in Methods.
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MERCURY AND HEPATIC ENZYMES
mercury-treated chicks did not differ significantly from the activities in control chicks. Starvation is known to depress the hepatic activities of fatty acid synthetase (Gibson and Hubbard, 1960; Butterworth et al., 1966) and fatty acid elongation (Elovson, 1965; Donaldson et al., 1970). However, inanition does not seem to be responsible for the mercury effects on fatty acid synthesis noted here for two reasons. First, glucose-6-phosphatase activity in mercury-treated chicks was not elevated, and marked elevations of the activity of this enzyme are indicative of inanition (Donaldson, 1973). Second, it appears that the effect of mercury on fatty acid synthesizing enzymes is rather specific because 6phosphogluconate dehydrogenase activity, which is correlated to fatty acid synthesis in liver in a variety of physiological states (Tepperman and Tepperman, 1958; Allee et al., 1972), was not affected by mercury in the present experiment. Chefurka (1957) demonstrated the in vitro inhibition of 6phosphogluconate dehydrogenase by mercury. The absence of inhibition in the present experiment coupled with the observed inhibitions of the fatty acid synthesizing enzymes may be related to the differential accessibility of the sulfhydryl groups of these enzymes. In any case, the lack of a depression by mercury of the activities of cytochrome c oxidase, glucose-6-phosphatase and 6phosphogluconate dehydrogenase suggests that the effects of mercury are more specific than those of a generalized toxicity. The observation that mercury stimulates the activity of acid phosphatase is in agreement with other reports on mercury stimulation of phosphohydrolases (Rapoport and Luebering, 1951; Miller etal., 1969). Acid phosphatase is a lysosomal enzyme (De Duve et al., 1955) and mercury tends to accumulate in lysosomes (Norseth and Brendeford, 1971). It has been suggested by the latter workers that the lysosomal accumulation of mercury may represent a detoxication process.
ACKNOWLEDGMENT The skillful technical assistance of Mrs. F. D. Suggs and Mr. W. C. Strickland is gratefully acknowledged. This research was supported in part by U. S. Public Health Service Grant No. HD02887, National Institutes of Health. REFERENCES Allee, G. L., D. R. Romsos, G. A. Leveille and D. H. Baker, 1972. Metabolic adaptation induced by meal-eating in the pig. J. Nutrition, 102: 1115-1122. Butterworth, P. H. W., R. B. Guchhait, H. Baum, E. B. Olson, S. A. Margolis and J. W. Porter, 1966. Relationship between nutritional status and fatty acid synthesis by microsomal and soluble enzymes of pigeon liver. Arch. Biochem. Biophys. 116: 453-457. Chefurka, W., 1957. Oxidative metabolism of carbohydrates in insects II. Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in the housefly. Enzymology, 18: 209-227. Cleland, K. W., and E. C. Slater, 1953. Respiratory granules of heart muscle. Biochem. J. 53: 547-556. De Duve, C , B. C. Pressman, R. Gianetto, R. Wattiaux and F. Appelmans, 1955. Tissue fractionation studies. Biochem. J. 60: 604-617. Dieter, M. P., 1974. Plasma enzyme activities in Coturnix quail fed graded doses of DDE, polychlorinated biphenyl, malatbion and mercuric chloride. Toxicol. App. Pharmacol. 27: 86-98. Donaldson, W. E., 1973. Glucose stimulation of fatty acid desaturation in liver of newly-hatched chicks. Biochim. Biophys. Acta, 316: 8-12. Donaldson, W. E., E. M. Wit-Peeters and H. R. Scholte, 1970. Fatty acid synthesis in rat liver: relative contributions of the mitochondrial, microsomal and non-particulate systems. Biochim. Biophys. Acta, 202: 35-42. Elovson, J., 1965. Conversions of palmitic and stearic acid in the intact rat. Biochim. Biophys. Acta, 106: 291-303. Gibson, D. M., and D. D. Hubbard, 1960. Incorporation of malonyl CoA into fatty acids by liver in starvation and alloxan-diabetes. Biochem. Biophys. Res. Commun. 3: 531-535. Glock, G. E., and P. McLean, 1953. Further studies on the properties and assay of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in rat liver. Biochem. J. 55: 400-408. Lucier, G., O. McDaniel, P. Brubaker and R. Klein, 1971/72. Effects of methylmercury hydroxide on
1616
W . E . DONALDSON AND J. P . THAXTON
rat liver microsomal enzymes. Chem. Biol. Interactions, 4: 265-280. Mason, J. V., and W. E. Donaldson, 1972. Fatty acid synthesizing systems in chick liver: influences of biotin deficiency and dietary fat. J. Nutrition, 102: 667-672. Miller, V. L., J. A. Mclntyre and G. E. Bearse, 1969. Kidney alkaline phosphatase in mercuric chloride injected chicks resistant and susceptible to leukosis. Poultry Sci. 48: 1487-1490. Norseth, T., and M. Brendeford, 1971. Intracellular distribution of inorganic and organic mercury in rat liver after exposure to methylmercury salts. Biochem. Pharmacol. 20: 1101-1107. Parkhurst, C. R., and P. Thaxton, 1973. Toxicity of mercury to young chickens 1. Effect on growth and mortality. Poultry Sci. 52: 273-276.
Rapoport, S., and J. Leubering, 1951. Glycerate-2, 3-diphosphatase. J. Biol. Chem. 189: 683-694. Singhal, R. L., S. Kacew and D. J. B. Sutherland, 1974. Metabolic alterations in liver and kidney following chronic methylmercury treatment and withdrawl. Environ. Res. 7: 220-229. Smith, L., 1955. Cytochromes a, a,, a2, and a3. In: Methods in Enzymology, vol. 2, S. P. Colowick and N. O. Kaplan, eds. Academic Press, New York, p. 735. Tepperman, J., and H. M. Tepperman, 1958. Effects of antecedent food intake pattern on hepatic lipogenesis. Am. J. Physiol. 193: 55-64. Thaxton, P., and C. R. Parkhurst, 1973. Toxicity of mercury to young chickens. 2. Gross changes in organs. Poultry Sci. 52: 277-281.
Debeaking Method for Bob white Quail1,2 H . R. WILSON, M . G. M I L L E R 3 AND C. R. DOUGLAS
Department of Poultry Science, Florida Agricultural Experiment Station, Gainesville, Florida 32611 (Received for publication January 14, 1975)
ABSTRACT Four experiments were conducted to determine the suitability of various debeaking procedures for Bobwhite quail at hatching or at one week of age. Two experiments were conducted using a "precision" type debeaking method with the following treatments: control; debeaked at hatching with debeaker guide plate holes of 2.38 or 2.78 mm.; debeaked at seven days of age using guide plate holes of 2.38, 2.78 or 3.18 mm. Two experiments tested a "touch-burn" method at hatching with the following treatments: control; burned 1/4 distance to nares; and burned 1/2 distance to nares. The "precision" type methods at hatching or seven days of age reduced mortality from cannibalism; however, these methods were found to be relatively slow and difficult, and the birds lacked uniformity in beak and body size at five weeks of age. Burning 1 / 2 distance to nares was too severe, causing a reduction in body weight and poor feed efficiency. Burning 1/4 distance to nares gave the most favorable results: growth and feed efficiency as good or better than controls, uniform birds and decreased cannibalism. POULTRY SCIENCE 54: 1616-1619, 1975
INTRODUCTION
O
NE of the most commonly accepted management practices for growing chickens is debeaking. Moderate or light debeakinghas been shown to have no adverse 1. Florida Agr. Exp. Sta. Journal Series No. 5749. 2. The use of tradenames does not imply endorsement or criticism of these products, or of similar products not mentioned. 3. Present address: Rose Acre Farms, Seymour, Ind.
effect on growth, feed conversion or mortality while usually resulting in decreased cannibalism and improved feathering (Darrow and Stotts, 1954; Huston et al., 1956; Camp et al., 1955). More severe methods of debeaking may cause a delay in sexual maturity, decreased egg production, decreased feed consumption, poorer feed efficiency and decreased weight gain (Hargreaves and Champion, 1965). More recently the development of a "precision" debeaking method (Bramhall, 1967) resulted in reduced stress
Department of Poultry Science, North Carolina State University, Raleigh, North Carolina 27607 (Received for publication January 14, 1975)
ABSTRACT Three groups of 6 male chicks each were fed a commercial diet and were given drinking water which contained either 0, 150 or 300 \x.g. of mercury/ml. as mercuric chloride from hatching to 3 weeks of age. The chicks were killed, the livers were removed and weighed, and the activities of selected enzymes were measured in the 800 x gav supernatant fractions of the liver homogenates. Liver weights were depressed from control values in chicks receiving 300 p.p.m. mercury but not in chicks receiving 150 p.p.m. Fatty acid synthetase specific activity was depressed by both levels of added mercury, but microsomal fatty acid elongation was depressed only by 300 p.p.m. of mercury. Both levels of added mercury stimulated acid phosphatase specific activity. The specific activities of cytochrome c oxidase, glucose-6phosphatase and 6-phosphogluconate dehydrogenase were unaffected by added mercury. The data support the hypothesis that mercury administration does not result in generalized hepatotoxicity. POULTRY SCIENCE 54: 1613-1616, 1975
INTRODUCTION
M
ERCURY compounds interact with sulfhydryl groups and have been used to inhibit the activities of a number of enzymes in vitrojhowever, there are few reports of in vivo effects of mercury on enzyme activities. Miller et al. (1969) reported the inhibition of kidney alkaline phosphatase by injections of mercuric chloride into chicks. Reductions of liver content of the microsomal cytochromes P-450 by b5 as well as the activities of aminopyrine demethylase and UDP glucuronyltransferase in rats by subcutaneous administration of methylmercury hydroxide were reported by Lucier et al. (1971/72). Singhal et al. (1974) reported increases of activity of several gluconeogenic enzymes in liver and kidney of rats treated with methylmercury. Dieter (1974) showed that dietary mercuric chloride reduced the plasma cholinesterase and increased the plasma lactate dehydrogenase activities in quail. The purpose of this investigation was to
1. Paper No. 4572 of the Journal Series of the North Carolina Agricultural Experiment Station, Raleigh, North Carolina.
determine the effects of a 3 week exposure to mercuric chloride in the drinking water of chicks on the hepatic activities of fatty acid synthetase, the microsomal system of fatty acid elongation, cytochrome c oxidase, acid phosphatase, glucose-6-phosphatase and 6-phosphogluconate dehydrogenase. The latter four enzymes are commonly used as subcellular markers for mitochondria, lysosomes, microsomes and cytosol, respectively (Donaldson et al., 1970; Mason and Donaldson, 1972). The physiological effects of exposure of chicks to mercury in the drinking water have been reported elsewhere (Parkhurst and Thaxton, 1973; Thaxton and Parkhurst, 1973). METHODS Male chicks were maintained in electrically-heated cages from day-old to 3 weeks of age, and a commercially prepared diet was available ad libitum throughout the experiment. The treatments consisted of adding 0, 150 or 300 ixg. of mercury/ml. of drinking water as mercuric chloride, and the drinking water was available ad libitum. At 3 weeks, 6 chicks were selected at random from each treatment and killed by cervical dislocation.
1613
1614
W. E. DONALDSON AND J. P. THAXTON
The livers were removed immediately and placed in cold 0.25 M sucrose. Each liver was minced, rinsed and homogenized in a Potter-Elvejhem tissue grinder with a Teflon pestle. After filtering through a nylon net, the homogenates were centrifuged for 10 min. at 800 x g av . The pellet was discarded and the supernatant fractions were used in all assays. All steps were carried out at 0-5°. Protein was determined in each fraction by the biuret method of Cleland and Slater (1953). Fatty acid synthetase and the microsomal system of fatty acid elongation activities were measured as described previously (Donaldson et al., 1970; Mason and Donaldson, 1972). The above assays were carried out with freshly prepared fractions. All other assays were carried out with frozen fractions which were freshly thawed. Cytochrome c oxidase was assayed by the procedure of Smith (1955). Acid phosphatase and glucose-6-phosphatase were assayed according to De Duve et al. (1955). The procedure of Glock and McLean (1953) was used to assay 6-phosphogluconate dehydrogenase. Prior to the assays for cytochrome c oxidase, acid phosphatase and glucose-6-phosphatase the fractions, in 1 ml. aliquots, were sonicated for 1 min. in the presence of 1 raM reduced glutathione. All assays were linear with respect to time and protein concentration. Enzyme activities were expressed in units as
TABLE 1.—Effects
follows: fatty acid synthetase and microsomal elongation of fatty acids, 1 unit = 1 (jimole malonyl-CoA incorporated into long-chain fatty acids/min. at 25°; cytochrome c oxidase, 1 unit = 1 ixmole cytochrome c oxidized/min. at 25°; acid phosphatase, 1 unit = 1 (xmole (3-glycerol phosphate hydrolyzed/min. at 37°; glucose6-phosphatase, 1 unit = 1 ^mole glucose-6phosphate hydrolyzed/min. at 37°; 6phosphogluconate dehydrogenase, 1 unit = 1 (jimole 6-phosphogluconate oxidized/min. at 25°. RESULTS AND DISCUSSION The experimental results are shown in Table 1. Liver weight was significantly depressed (P < 0.01) by 300 p.p.m. mercury in the drinking water, but 150 p.p.m. was without effect as compared with controls. Both levels of mercury depressed fatty acid synthetase activity below control values (P < 0.01), but only the 300 p.p.m. level of mercury significantly depressed (P < 0.05) the activity of the microsomal system of fatty acid elongation. Acid phosphatase activity was stimulated above control values by both 150 p.p.m. (P < 0.05) and 300 p.p.m. (P < 0.01) of mercury. The activities of cytochrome c oxidase, glucose-6-phosphatase and 6-phosphogluconate dehydrogenase in
of mercury in the drinking water on liver weight and the activities of various liver enzymes Enzyme activity, mUnits/mg. protein 1
drinking water, ug./ml. 0 150 300
Liver weight, g-
Fatty acid synthetase
Microsomal elongation
2.24 ± 0.23 10.5 ± 0.4 0.23 ± 0.03 9.3 ± 1.6 1.15 ± 0 . 1 1 * * 0.15 ± 0 . 0 1 7.5 ± 0.4** 0.93 ±0.15** 0.13 ± 0.01*
Cytochrome c oxidase
Acid phosphatase
475 ± 54 461 ± 27 476 ± 54
16 ± 1 . 8 23 ± 0.2* 30 ± 0.2**
6-phosphoGlucose-6 gluconate phosphatase dehydrogenase 66 ± 11 87 ± 5 76 ± 3
3.4 ± 0.3 3.8 ± 0 . 1 3.4 ± 0.2
•Each value represents the mean ± S.E.M. of 6 livers. Each assay was carried out in duplicate. Means of the mercury treated chicks were compared with the means of the control chicks by t tests. The symbols * and ** indicate that the means were statistically significantly different from control means, P < 0.05 and P < 0.01, respectively. Enzyme units are defined in Methods.
1615
MERCURY AND HEPATIC ENZYMES
mercury-treated chicks did not differ significantly from the activities in control chicks. Starvation is known to depress the hepatic activities of fatty acid synthetase (Gibson and Hubbard, 1960; Butterworth et al., 1966) and fatty acid elongation (Elovson, 1965; Donaldson et al., 1970). However, inanition does not seem to be responsible for the mercury effects on fatty acid synthesis noted here for two reasons. First, glucose-6-phosphatase activity in mercury-treated chicks was not elevated, and marked elevations of the activity of this enzyme are indicative of inanition (Donaldson, 1973). Second, it appears that the effect of mercury on fatty acid synthesizing enzymes is rather specific because 6phosphogluconate dehydrogenase activity, which is correlated to fatty acid synthesis in liver in a variety of physiological states (Tepperman and Tepperman, 1958; Allee et al., 1972), was not affected by mercury in the present experiment. Chefurka (1957) demonstrated the in vitro inhibition of 6phosphogluconate dehydrogenase by mercury. The absence of inhibition in the present experiment coupled with the observed inhibitions of the fatty acid synthesizing enzymes may be related to the differential accessibility of the sulfhydryl groups of these enzymes. In any case, the lack of a depression by mercury of the activities of cytochrome c oxidase, glucose-6-phosphatase and 6phosphogluconate dehydrogenase suggests that the effects of mercury are more specific than those of a generalized toxicity. The observation that mercury stimulates the activity of acid phosphatase is in agreement with other reports on mercury stimulation of phosphohydrolases (Rapoport and Luebering, 1951; Miller etal., 1969). Acid phosphatase is a lysosomal enzyme (De Duve et al., 1955) and mercury tends to accumulate in lysosomes (Norseth and Brendeford, 1971). It has been suggested by the latter workers that the lysosomal accumulation of mercury may represent a detoxication process.
ACKNOWLEDGMENT The skillful technical assistance of Mrs. F. D. Suggs and Mr. W. C. Strickland is gratefully acknowledged. This research was supported in part by U. S. Public Health Service Grant No. HD02887, National Institutes of Health. REFERENCES Allee, G. L., D. R. Romsos, G. A. Leveille and D. H. Baker, 1972. Metabolic adaptation induced by meal-eating in the pig. J. Nutrition, 102: 1115-1122. Butterworth, P. H. W., R. B. Guchhait, H. Baum, E. B. Olson, S. A. Margolis and J. W. Porter, 1966. Relationship between nutritional status and fatty acid synthesis by microsomal and soluble enzymes of pigeon liver. Arch. Biochem. Biophys. 116: 453-457. Chefurka, W., 1957. Oxidative metabolism of carbohydrates in insects II. Glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in the housefly. Enzymology, 18: 209-227. Cleland, K. W., and E. C. Slater, 1953. Respiratory granules of heart muscle. Biochem. J. 53: 547-556. De Duve, C , B. C. Pressman, R. Gianetto, R. Wattiaux and F. Appelmans, 1955. Tissue fractionation studies. Biochem. J. 60: 604-617. Dieter, M. P., 1974. Plasma enzyme activities in Coturnix quail fed graded doses of DDE, polychlorinated biphenyl, malatbion and mercuric chloride. Toxicol. App. Pharmacol. 27: 86-98. Donaldson, W. E., 1973. Glucose stimulation of fatty acid desaturation in liver of newly-hatched chicks. Biochim. Biophys. Acta, 316: 8-12. Donaldson, W. E., E. M. Wit-Peeters and H. R. Scholte, 1970. Fatty acid synthesis in rat liver: relative contributions of the mitochondrial, microsomal and non-particulate systems. Biochim. Biophys. Acta, 202: 35-42. Elovson, J., 1965. Conversions of palmitic and stearic acid in the intact rat. Biochim. Biophys. Acta, 106: 291-303. Gibson, D. M., and D. D. Hubbard, 1960. Incorporation of malonyl CoA into fatty acids by liver in starvation and alloxan-diabetes. Biochem. Biophys. Res. Commun. 3: 531-535. Glock, G. E., and P. McLean, 1953. Further studies on the properties and assay of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase in rat liver. Biochem. J. 55: 400-408. Lucier, G., O. McDaniel, P. Brubaker and R. Klein, 1971/72. Effects of methylmercury hydroxide on
1616
W . E . DONALDSON AND J. P . THAXTON
rat liver microsomal enzymes. Chem. Biol. Interactions, 4: 265-280. Mason, J. V., and W. E. Donaldson, 1972. Fatty acid synthesizing systems in chick liver: influences of biotin deficiency and dietary fat. J. Nutrition, 102: 667-672. Miller, V. L., J. A. Mclntyre and G. E. Bearse, 1969. Kidney alkaline phosphatase in mercuric chloride injected chicks resistant and susceptible to leukosis. Poultry Sci. 48: 1487-1490. Norseth, T., and M. Brendeford, 1971. Intracellular distribution of inorganic and organic mercury in rat liver after exposure to methylmercury salts. Biochem. Pharmacol. 20: 1101-1107. Parkhurst, C. R., and P. Thaxton, 1973. Toxicity of mercury to young chickens 1. Effect on growth and mortality. Poultry Sci. 52: 273-276.
Rapoport, S., and J. Leubering, 1951. Glycerate-2, 3-diphosphatase. J. Biol. Chem. 189: 683-694. Singhal, R. L., S. Kacew and D. J. B. Sutherland, 1974. Metabolic alterations in liver and kidney following chronic methylmercury treatment and withdrawl. Environ. Res. 7: 220-229. Smith, L., 1955. Cytochromes a, a,, a2, and a3. In: Methods in Enzymology, vol. 2, S. P. Colowick and N. O. Kaplan, eds. Academic Press, New York, p. 735. Tepperman, J., and H. M. Tepperman, 1958. Effects of antecedent food intake pattern on hepatic lipogenesis. Am. J. Physiol. 193: 55-64. Thaxton, P., and C. R. Parkhurst, 1973. Toxicity of mercury to young chickens. 2. Gross changes in organs. Poultry Sci. 52: 277-281.
Debeaking Method for Bob white Quail1,2 H . R. WILSON, M . G. M I L L E R 3 AND C. R. DOUGLAS
Department of Poultry Science, Florida Agricultural Experiment Station, Gainesville, Florida 32611 (Received for publication January 14, 1975)
ABSTRACT Four experiments were conducted to determine the suitability of various debeaking procedures for Bobwhite quail at hatching or at one week of age. Two experiments were conducted using a "precision" type debeaking method with the following treatments: control; debeaked at hatching with debeaker guide plate holes of 2.38 or 2.78 mm.; debeaked at seven days of age using guide plate holes of 2.38, 2.78 or 3.18 mm. Two experiments tested a "touch-burn" method at hatching with the following treatments: control; burned 1/4 distance to nares; and burned 1/2 distance to nares. The "precision" type methods at hatching or seven days of age reduced mortality from cannibalism; however, these methods were found to be relatively slow and difficult, and the birds lacked uniformity in beak and body size at five weeks of age. Burning 1 / 2 distance to nares was too severe, causing a reduction in body weight and poor feed efficiency. Burning 1/4 distance to nares gave the most favorable results: growth and feed efficiency as good or better than controls, uniform birds and decreased cannibalism. POULTRY SCIENCE 54: 1616-1619, 1975
INTRODUCTION
O
NE of the most commonly accepted management practices for growing chickens is debeaking. Moderate or light debeakinghas been shown to have no adverse 1. Florida Agr. Exp. Sta. Journal Series No. 5749. 2. The use of tradenames does not imply endorsement or criticism of these products, or of similar products not mentioned. 3. Present address: Rose Acre Farms, Seymour, Ind.
effect on growth, feed conversion or mortality while usually resulting in decreased cannibalism and improved feathering (Darrow and Stotts, 1954; Huston et al., 1956; Camp et al., 1955). More severe methods of debeaking may cause a delay in sexual maturity, decreased egg production, decreased feed consumption, poorer feed efficiency and decreased weight gain (Hargreaves and Champion, 1965). More recently the development of a "precision" debeaking method (Bramhall, 1967) resulted in reduced stress