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Sulfur Amino Acid Requirement of Broiler Chickens from 3 to 6 Weeks of Age1
Sulfur Amino Acid Requirement of Broiler Chickens from 3 to 6 Weeks of Age 1 LEO S. JENSEN, CRAIG L. WYATT, and BRYAN I. FANCHER Department of Poultry Science, University of Georgia, Athens, Georgia 30602 (Received for publication December 14, 1987)
1989 Poultry Science 68:163-168 INTRODUCTION
Requirements for TSAA for broilers fed diets containing 3,200 kcal ME/kg as listed by the National Research Council (NRC) in 1984 are .93% from 0 to 3 wk, .72% from 3 to 6 wk, and .60% from 6 to 8 wk of age. Considerable research has been conducted to determine the requirement during the starting phase, but limited information is available in refereed journals on the requirement after 3 wk of age. Thomas et al. (1978) summarized the research data on requirements of broilers at different ages for TSAA, and indicated that most of the studies were done with relatively small numbers of birds in cages, thus suggesting caution in extrapolating the requirements to field conditions. In experiments conducted in floor pens, Patel et al. (1980) observed that the kind of anticoccidial
'Supported by State and Hatch funds allocated to the Georgia Agricultural Experiment Stations of the University of Georgia.
163
drug used in the feed influenced the requirement of broiler chicks for these amino acids. The TSAA requirement for maximum growth in the presence of monensin was .92% from 0 to 33 days and .69% from 33 to 49 days, but .79% from 49 to 54 days of age during the drug withdrawal period in the absence of monensin. Wheeler and Latshaw (1981) in studies with broilers in floor pens indicated a requirement between .70 and .76% for TSAA from 3 to 6 wk of age. In determining the levels to be used in commercial broiler production, the criteria used for evaluation of the TSAA requirement become of concern. In most laboratory studies, the criteria are only growth rate and feed efficiency. Other criteria of importance in commercial production include abdominal fat deposition and feathering. Another consideration is the presence of other feed ingredients that may influence the requirement. Patel et al. (1980) indicated that the requirement may be higher in the presence of monensin than in the presence of other anticoccidial drugs. A protective effect of methionine
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ABSTRACT Two experiments were conducted to determine if the TSAA level suggested by the National Research Council (NRC) in 1984 was adequate for optimum performance of 3 to 6-wk-old broilers, and to assess the effect of added copper on the TSAA requirement. A 2 x 3 x 2 factorial arrangement involving two copper (0 and 240 ppm) and three TSAA levels (.72, .78 and .84%) and two sexes was used in each experiment. Copper sulfate (CuSCy5H 2 0) and DL-methionine were the dietary supplements to pelleted diets. There were four groups of 20 males or 20 females in each experiment, housed in floor pens. Methionine supplementation significantly improved body weight gain and feed efficiency in males but not in females. A significant copper x methionine interaction was observed, with methionine supplementation improving feed efficiency more in the presence of copper than in its absence. Abdominal fat per unit of body weight was significantly reduced by both methionine and copper in females but not in males. In a second experiment, methionine significantly improved body weight gain in males fed no added copper and significantly reduced abdominal fat per unit of body weight. Methionine supplementation improved body weight gain in males more in the absence than in the presence of copper (significant TSAA X copper interaction). Methionine supplementation had no significant effects on performance of females in the second experiment, but copper supplementation significantly improved feed efficiency. Combined data from the two experiments showed that in males body weight gain and feed efficiency were significantly increased and abdominal fat significantly decreased, whereas in females, only body weight gain was significantly increased and abdominal fat significantly decreased by increasing the dietary TSAA level. The TSAA requirement of .72% recommended by the NRC for 3 to 6-wk-old broilers appears inadequate; a minimum requirement of .78% is suggested. (Key words: broilers, methionine, sulfur amino acids, copper, sex)
JENSEN ET AL.
164
against copper toxicity was observed by Jensen and Maurice (1979), and Robbins and Baker (1980) reported that the requirement for TSAA of broiler chicks was significantly increased by adding 250 or 500 ppm of copper to the diet. Wang et al. (1987) also observed that methionine requirement of broiler chicks increased when pharmacological levels of copper were fed. Waldroup et al. (1979), however, failed to observe an influence of 250 ppm of copper on the TSAA requirements of young broiler chicks. The purpose of the present investigations was to estimate the quantitative requirement for TSAA of male and female broiler chicks reared in floor pens and fed practical diets with and without added copper.
Two experiments were conducted with male and female chicks of a commercial strain (Arbor Acre female x Peterson male) cross from 3 to 6 wk of age. The first experiment was conducted in the fall (October) and the second in winter (January) in an open-sided house with curtains. Chicks were fed a practical starter diet containing 23% protein and 3,100 kcal ME/kg for the first 3 wk in floor pens. At 3 wk of age, birds within sexes were randomly assigned to floor pens containing approximately 2.4 X 2.6 m floor space and wood shavings as litter in each experiment. Four pens of 20 males and four pens of 20 females were fed each of six experimental diets. A block design was used for both diet and sex. All birds received feed and water ad libitum and were subjected to continuous light. Chicks in both experiments were fed a basal diet calculated to contain .72% TSAA or the same diet supplemented with DL-methionine to provide levels of either .78 or .84% TSAA. Diets were fed with and without a supplement of copper sulfate (CuSCy5H 2 0) providing 240 mg/kg of copper for a total of six diets. All diets were fed in pelleted form. Composition of the basal diets used in the two experiments is presented in Table 1. In each experiment, the corn and soybean meal were analyzed for CP prior to formulating and mixing the diets. These protein values were then used in regression equations determined by the Degussa Corporation (Teterboro, NJ) to predict the methionine and cystine content of the ingredients. Therefore, the composition of the basal diets used in the two different experiments differs slightly in
RESULTS
The analyzed values for TSAA of the basal diets used in Experiments 1 and 2 were .711 and .716, respectively (Table 2). These values were very close to the calculated values of .72%. Body weight gain of males in Experiment 1 were significantly improved by methionine supplementation; copper, however, did not significantly improve growth rate, nor was there a significant interaction between copper and TSAA (Table 3). Response to methionine supplementation in females for body weight gain was not significant (P = .07), and copper supplementation had no significant influence nor was there a copper-TSAA interaction. In the presence of added copper, feed efficiency of males was significantly improved by adding methionine to the basal diet, resulting in a significant copper x TSAA interaction (Table 3). No significant effects on feed efficiency were observed among females for either methionine or copper supplementation. Abdominal fat content was not significantly affected by dietary treatments in males but was significantly re-
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MATERIALS AND METHODS
order to obtain the same calculated level of TSAA (.72%). Samples of the basal diets in both experiments were analyzed for content of several amino acids by ion-exchange chromatography. The method of analysis is detailed in a handbook entitled "Nutritional Reports and Animal Nutrition" published by Degussa Corporation (1987). Performic acid oxidation was performed prior to hydrolysis to allow quantitative analyses of methionine and cystine. Birds were weighed by pen at 3 and 6 wk of age, and total feed consumed per pen from 3 to 6 wk was determined in order to calculate feed:gain ratio. At the end of each experiment, four birds from each pen were randomly selected for determination of the abdominal fat content per unit of body weight. Fat surrounding the gizzard and intestines extending within the ischium and surrounding the bursa was considered as abdominal fat. Within each experiment, data for each parameter within each sex were analyzed by two-way ANOVA using the General Linear Models Procedures of SAS (1982). Data from the two experiments were also analyzed on a combined basis for the two sexes to compare responses to varying TSAA levels. Comparisons among treatment means were accomplished by student's t test at a probability level of 5%.
SULFUR AMINO ACID REQUIREMENT
165
TABLE 1. Composition of basal diets Experiment 2
1
Ingredient
(g/ IUU
g)
-
61.20 30.16 4.82 1.59 1.24 .44 .25 .05 .05 .05 .12 .03
60.30 30.83 5.04 1.59 1.24 .44 .25 .05 .05 .05 .12 .04
3,200 20.0 .9 .42 .38 .34 .72
3,200 20.0 .9 .42 .38 .34 .72
'Vitamin premix provides (per kilogram of diet): vitamin A, 5,500 IU; vitamin D 3 , 1,100 ICU; vitamin E, 11 IU; riboflavin, 4.4 mg; Ca pantothenate, 9.6 mg; nicotinic acid, 44 mg; choline CI, 220 mg; vitamin B n , 6.6 Mg; vitamin B 6 , 2.2 mg; menadione sodium bisulfite, 3.45 mg; folic acid, .55 mg; d-biotin, .11 mg; thiamine mononitrate, 2.2 mg; ethoxyquin, 124 mg. 2
Trace mineral mix provides (milligrams per kilogram of diet): Mn, 60; Zn, 50; Fe, 30; Cu, 5; I, 1.05.
3
Supplying .1 mg Se/kg of diet.
4
Bacitracin MD50 has a concentration of 50 g bacitracin/454 g premix.
5
Supplying 110 mg monensin/kg of diet.
duced in females by both methionine and copper supplementation. In Experiment 2, body weight gain of males was significantly improved by copper supplementation and by methionine supplementation in the absence of added copper (Table 4). A significant interaction was observed between TSAA and copper levels, with methionine supplementation improving weight gain in the absence of copper but not in the presence. No significant treatment effects among females were observed for body weight gain. Feed efficiency was not significantly affected by diet for males. Copper supplementation significantly improved feed efficiency in females. Abdominal fat content was significantly less in males fed diets supplemented with additional methionine, whereas copper supplementation had no affect. No significant treatment effects on abdominal fat were observed in females.
TABLE 2. Analyzed amino acid composition of broiler diets1 Experiment Amino acid
1
2
Methionine Cystine TSAA Lysine Leucine Isoleucine Threonine Valine Arginine Glycine Serine Tryptophan
.351 .360 .711 1.063 1.820 .804 .758 .896 1.321 .869 .998 ND 2
.363 .353 .716 1.014 1.730 .818 .781 .977 1.293 .874 1.004 .242
1 Determined on one sample per diet and expressed on an "as fed" basis. 2
ND = Not determined.
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Corn, ground yellow Soybean meal, dehulled Fat, poultry Dicalcium phosphate (21.3% Ca, 18.7% P) Limestone, ground Salt Vitamin mix 1 Trace mineral mix2 Selenium premix 3 Bacitracin MD50 4 Monensin premix 5 DL-Methionine Calculated composition: ME, kcal/kg Protein, % Calcium, % Phosphorus, available, % Methionine, % Cystine, % TSAA, %
(ppm)
0 0 0 240 240 240
(%)
.72 .78 .84 .72 .78 .84
1,174 1,238 1,245 1,175 1,274 1,303
Males
(g/chick)
.0017 .13 .51
± 21 ± 21 abc 34 be : 17ab ± 29,bc
a
1,035 1,064 1,086 1,033 1,045 1,077 .07 .54 .91
± 24 ± 23 ± 13 ± 21 ± 17 ± 8
Females
BW gain (3 to 6 wk)
.008
.89
.0001
.459 ± .008 .481 ± .003 .472 ± .002 .435 ± .015 .483 ± .008 .500 ± .003
Males
(ppm)
0 0 0 240 240 240
(%)
.72 .78 .84 .72 .78 .84
.30 .003 .033
1,372+ 8fc
(g/chick)
1,093 1,088 1,100 1,100 1,097 1,122 .48 .34
+ 22 + 12 + 15 + 12 + 22 + 12
Females
BW gain (3 to 6 wk)
1,305 + 1 2 a 1,356 ± 17 u 1,349 ± l l b 1,380+ 15 u 1,362 ± 10 b
Males
.14 .07 .29
.485 + .014 .510 ± .005 .515 + .005 .513 + .012 .535 ± .015 .513 + .010
(g/g)
.31 .03 .98
.478 ± .481 + .493 + .498 ± .498 ± .508 ±
.00 .0 .00 .00 .00 .00
Females
Gain:feed ratio (3 to 6 wk) Males
Values within a column with no common superscripts are significantly different (P<.05).
Source of variation, pro babilities TSAA Cu TSAA X Cu
Added Cu
Treatment
.48 .64 .98
.478 + . .469 + . .478 + . .483 + . .472 + . .481 + .
TABLE 4. Effect (x ± SE) of dietary treatments on body weight gain, feed.gain ratio, and abdo
(g/g)
Females
Gain:feed ratio (3 to 6 wk)
Values within a column with no common superscripts are significantly different (P<.05).
TSAA
c
Source of variation, probabilities TSAA Cu TSAA X Cu
Added Cu
TSAA
Treatment
TABLE 3. Effect (x ± SE) of dietary treatments on body weight gain, feed-.gain ratio, and abdo
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SULFUR AMINO ACID REQUIREMENT
167
TABLE 5. Effect (x + SE) of total sulfur amino acid levels on performance of each sex of broilers (data from two experiments combined) Gaimfeed ratio (3 to 6 wk)
BW gain (3 to 6 wk) TSAA
(%) .72 .78 .84
Males
Females
Males
(g/chick) 1,259 ± 9° 1,307 ± 9 a 1,317+ 10 a
1,065 : ab 1,073 : 10' 1,096 : 10 a
Females
Males
.484 + .005a .480 + .005a .489 ± .005a
1.90 ± .06a 1.71 + ,06b 1.68 ± 06 L
Females (% BW)
(g/g) .472 + .005° .501 ± .005a .500 ± ,005a
Abdominal fat (6 wk)
2.17 ± 06 a 1.99 ± 0 6 b 1.99+ .06b
a,bValues within a column with no common superscripts are significantly different (P<.05).
DISCUSSION
The results of these experiments demonstrate that the NRC (1984) value of .72% is inadequate as a minimum broiler requirement for TSAA from 3 to 6 wk of age for the strain of chickens used in the present study. Differences between responses to methionine supplementation observed in the two experiments may be related to differences in season of the year in which the experiments were conducted in curtain-sided houses. Analysis of the combined data, however, revealed significant improvement in all parameters (increased body weight gain, feed efficiency, and reduced abdominal fat) when the level of TSAA was increased from .72 to .78%. Although the response to methionine supplementation was generally less in females than in males, analysis of the combined data showed a significant increase in body weight gain and a significant reduction in abdominal fat per unit
of body weight for this sex by increasing the dietary level of TSAA. The data suggest that a value of .78% would be better as a minimum requirement of broiler chickens at this age than the currently recommended .72%. The results of this study also demonstrate that using only body weight gain and feed efficiency as the criteria for establishing a minimum requirement for TSAA for broiler production may be inadequate. In the second experiment, a significant reduction in abdominal fat was observed by methionine supplementation, even though no significant differences in body weight gain or feed efficiency were observed in the male broilers. Subjective observations of the feathering of the birds and feathers in the litter among pens were made, but no obvious differences in the treatments were observed. Inconsistent results were obtained with copper supplementation in the study, and body weight was significantly improved in males by copper supplementation in only one experiment. Likewise, in one experiment, copper supplementation significantly decreased abdominal fat and improved feed efficiency in females. Evidence for an interaction between copper supplementation and methionine requirement was observed for males in both experiments, as there was a significant interaction with body weight gain in the first experiment and feed efficiency in the second for these two dietary components. Analysis of the combined data from the two experiments, however, revealed no significant interactions between copper and TSAA for either sex. Thus these data with older broilers only weakly support the observations of Robbins and Baker (1980) and Wang et al. (1987) that copper supplementation increases the requirement of chicks for TSAA.
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When data from the two experiments were analyzed on a combined basis, significant (P< .05) increases in body weight gain and feed efficiency and a significant decrease in abdominal fat were observed in males by increasing TSAA level from .72 to .78% (Table 5). No further significant changes were seen by increasing the TSAA level to .84%. In females body gain was significantly higher at the highest TSAA supplementation level (.84%) than at the lowest level. The .78% or higher TSAA supplementation level resulted in a significant reduction in abdominal fat as a percentage of body weight. In the analysis of the combined data, no significant copper x TSAA interaction was observed for either sex.
168
JENSEN ETAL. ACKNOWLEDGMENTS
The authors are indebted to the Degussa Corporation (Teterboro, NJ) for conducting the amino acid analyses of the basal diets. REFERENCES
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Anonymous, 1987. Nutritional Reports and Animal Nutrition. Degussa Corp., Teterboro, NJ. Jensen, L. S., andD. V. Maurice, 1979. Influence of sulfur amino acids on copper toxicity in chicks. J. Nutr. 109:91-97. National Research Council, 1984. Nutrient Requirements of Poultry. National Academy Press, Washington, DC. Patel, M. B., K. O. Bishawi, G. W. Nam, and J. McGinnis, 1980. Effect of drug additives and type of diet on methionine requirement for growth, feed efficiency, and feathering of broilers reared in floor pens. Poultry Sci. 59:2111-2120. Robbins, K. R., and D. H. Baker, 1980. Effect of sulfur
amino acid level and source on the performance of chicks fed high levels of copper. Poultry Sci. 59:12461253. SAS, 1982. Statistical Analysis System (SAS) User's Guide. SAS Inst. Inc., Cary, NC. Thomas, O. P., P. V. Twining, Jr., and E. H. Bossard, 1978. The lysine and sulfur amino acid requirements of broilers. Pages 27-35 in: Proc. Ga. Nutr. Conf., Univ. Georgia, Athens, GA. Waldroup, P. W., C. J. Mabray, J. R. Blackman, and Z. B. Johnson, 1979. The influence of copper sulfate on the methionine requirement of the young broiler chick. Nutr. Rep. Int. 20:303-308. Wang, J. S., S. R. Rogers, andG. M. Pesti, 1987. Influence of choline and sulfate on copper and toxicity and substitution of and antagonism between methionine and copper supplements to chick diets. Poultry Sci. 66:1500-1507. Wheeler, K. B., and J. D. Latshaw, 1981. Sulfur amino acid requirements and interactions in broilers during two growth periods. Poultry Sci. 60:228-236.
1989 Poultry Science 68:163-168 INTRODUCTION
Requirements for TSAA for broilers fed diets containing 3,200 kcal ME/kg as listed by the National Research Council (NRC) in 1984 are .93% from 0 to 3 wk, .72% from 3 to 6 wk, and .60% from 6 to 8 wk of age. Considerable research has been conducted to determine the requirement during the starting phase, but limited information is available in refereed journals on the requirement after 3 wk of age. Thomas et al. (1978) summarized the research data on requirements of broilers at different ages for TSAA, and indicated that most of the studies were done with relatively small numbers of birds in cages, thus suggesting caution in extrapolating the requirements to field conditions. In experiments conducted in floor pens, Patel et al. (1980) observed that the kind of anticoccidial
'Supported by State and Hatch funds allocated to the Georgia Agricultural Experiment Stations of the University of Georgia.
163
drug used in the feed influenced the requirement of broiler chicks for these amino acids. The TSAA requirement for maximum growth in the presence of monensin was .92% from 0 to 33 days and .69% from 33 to 49 days, but .79% from 49 to 54 days of age during the drug withdrawal period in the absence of monensin. Wheeler and Latshaw (1981) in studies with broilers in floor pens indicated a requirement between .70 and .76% for TSAA from 3 to 6 wk of age. In determining the levels to be used in commercial broiler production, the criteria used for evaluation of the TSAA requirement become of concern. In most laboratory studies, the criteria are only growth rate and feed efficiency. Other criteria of importance in commercial production include abdominal fat deposition and feathering. Another consideration is the presence of other feed ingredients that may influence the requirement. Patel et al. (1980) indicated that the requirement may be higher in the presence of monensin than in the presence of other anticoccidial drugs. A protective effect of methionine
Downloaded from http://ps.oxfordjournals.org/ by guest on April 7, 2015
ABSTRACT Two experiments were conducted to determine if the TSAA level suggested by the National Research Council (NRC) in 1984 was adequate for optimum performance of 3 to 6-wk-old broilers, and to assess the effect of added copper on the TSAA requirement. A 2 x 3 x 2 factorial arrangement involving two copper (0 and 240 ppm) and three TSAA levels (.72, .78 and .84%) and two sexes was used in each experiment. Copper sulfate (CuSCy5H 2 0) and DL-methionine were the dietary supplements to pelleted diets. There were four groups of 20 males or 20 females in each experiment, housed in floor pens. Methionine supplementation significantly improved body weight gain and feed efficiency in males but not in females. A significant copper x methionine interaction was observed, with methionine supplementation improving feed efficiency more in the presence of copper than in its absence. Abdominal fat per unit of body weight was significantly reduced by both methionine and copper in females but not in males. In a second experiment, methionine significantly improved body weight gain in males fed no added copper and significantly reduced abdominal fat per unit of body weight. Methionine supplementation improved body weight gain in males more in the absence than in the presence of copper (significant TSAA X copper interaction). Methionine supplementation had no significant effects on performance of females in the second experiment, but copper supplementation significantly improved feed efficiency. Combined data from the two experiments showed that in males body weight gain and feed efficiency were significantly increased and abdominal fat significantly decreased, whereas in females, only body weight gain was significantly increased and abdominal fat significantly decreased by increasing the dietary TSAA level. The TSAA requirement of .72% recommended by the NRC for 3 to 6-wk-old broilers appears inadequate; a minimum requirement of .78% is suggested. (Key words: broilers, methionine, sulfur amino acids, copper, sex)
JENSEN ET AL.
164
against copper toxicity was observed by Jensen and Maurice (1979), and Robbins and Baker (1980) reported that the requirement for TSAA of broiler chicks was significantly increased by adding 250 or 500 ppm of copper to the diet. Wang et al. (1987) also observed that methionine requirement of broiler chicks increased when pharmacological levels of copper were fed. Waldroup et al. (1979), however, failed to observe an influence of 250 ppm of copper on the TSAA requirements of young broiler chicks. The purpose of the present investigations was to estimate the quantitative requirement for TSAA of male and female broiler chicks reared in floor pens and fed practical diets with and without added copper.
Two experiments were conducted with male and female chicks of a commercial strain (Arbor Acre female x Peterson male) cross from 3 to 6 wk of age. The first experiment was conducted in the fall (October) and the second in winter (January) in an open-sided house with curtains. Chicks were fed a practical starter diet containing 23% protein and 3,100 kcal ME/kg for the first 3 wk in floor pens. At 3 wk of age, birds within sexes were randomly assigned to floor pens containing approximately 2.4 X 2.6 m floor space and wood shavings as litter in each experiment. Four pens of 20 males and four pens of 20 females were fed each of six experimental diets. A block design was used for both diet and sex. All birds received feed and water ad libitum and were subjected to continuous light. Chicks in both experiments were fed a basal diet calculated to contain .72% TSAA or the same diet supplemented with DL-methionine to provide levels of either .78 or .84% TSAA. Diets were fed with and without a supplement of copper sulfate (CuSCy5H 2 0) providing 240 mg/kg of copper for a total of six diets. All diets were fed in pelleted form. Composition of the basal diets used in the two experiments is presented in Table 1. In each experiment, the corn and soybean meal were analyzed for CP prior to formulating and mixing the diets. These protein values were then used in regression equations determined by the Degussa Corporation (Teterboro, NJ) to predict the methionine and cystine content of the ingredients. Therefore, the composition of the basal diets used in the two different experiments differs slightly in
RESULTS
The analyzed values for TSAA of the basal diets used in Experiments 1 and 2 were .711 and .716, respectively (Table 2). These values were very close to the calculated values of .72%. Body weight gain of males in Experiment 1 were significantly improved by methionine supplementation; copper, however, did not significantly improve growth rate, nor was there a significant interaction between copper and TSAA (Table 3). Response to methionine supplementation in females for body weight gain was not significant (P = .07), and copper supplementation had no significant influence nor was there a copper-TSAA interaction. In the presence of added copper, feed efficiency of males was significantly improved by adding methionine to the basal diet, resulting in a significant copper x TSAA interaction (Table 3). No significant effects on feed efficiency were observed among females for either methionine or copper supplementation. Abdominal fat content was not significantly affected by dietary treatments in males but was significantly re-
Downloaded from http://ps.oxfordjournals.org/ by guest on April 7, 2015
MATERIALS AND METHODS
order to obtain the same calculated level of TSAA (.72%). Samples of the basal diets in both experiments were analyzed for content of several amino acids by ion-exchange chromatography. The method of analysis is detailed in a handbook entitled "Nutritional Reports and Animal Nutrition" published by Degussa Corporation (1987). Performic acid oxidation was performed prior to hydrolysis to allow quantitative analyses of methionine and cystine. Birds were weighed by pen at 3 and 6 wk of age, and total feed consumed per pen from 3 to 6 wk was determined in order to calculate feed:gain ratio. At the end of each experiment, four birds from each pen were randomly selected for determination of the abdominal fat content per unit of body weight. Fat surrounding the gizzard and intestines extending within the ischium and surrounding the bursa was considered as abdominal fat. Within each experiment, data for each parameter within each sex were analyzed by two-way ANOVA using the General Linear Models Procedures of SAS (1982). Data from the two experiments were also analyzed on a combined basis for the two sexes to compare responses to varying TSAA levels. Comparisons among treatment means were accomplished by student's t test at a probability level of 5%.
SULFUR AMINO ACID REQUIREMENT
165
TABLE 1. Composition of basal diets Experiment 2
1
Ingredient
(g/ IUU
g)
-
61.20 30.16 4.82 1.59 1.24 .44 .25 .05 .05 .05 .12 .03
60.30 30.83 5.04 1.59 1.24 .44 .25 .05 .05 .05 .12 .04
3,200 20.0 .9 .42 .38 .34 .72
3,200 20.0 .9 .42 .38 .34 .72
'Vitamin premix provides (per kilogram of diet): vitamin A, 5,500 IU; vitamin D 3 , 1,100 ICU; vitamin E, 11 IU; riboflavin, 4.4 mg; Ca pantothenate, 9.6 mg; nicotinic acid, 44 mg; choline CI, 220 mg; vitamin B n , 6.6 Mg; vitamin B 6 , 2.2 mg; menadione sodium bisulfite, 3.45 mg; folic acid, .55 mg; d-biotin, .11 mg; thiamine mononitrate, 2.2 mg; ethoxyquin, 124 mg. 2
Trace mineral mix provides (milligrams per kilogram of diet): Mn, 60; Zn, 50; Fe, 30; Cu, 5; I, 1.05.
3
Supplying .1 mg Se/kg of diet.
4
Bacitracin MD50 has a concentration of 50 g bacitracin/454 g premix.
5
Supplying 110 mg monensin/kg of diet.
duced in females by both methionine and copper supplementation. In Experiment 2, body weight gain of males was significantly improved by copper supplementation and by methionine supplementation in the absence of added copper (Table 4). A significant interaction was observed between TSAA and copper levels, with methionine supplementation improving weight gain in the absence of copper but not in the presence. No significant treatment effects among females were observed for body weight gain. Feed efficiency was not significantly affected by diet for males. Copper supplementation significantly improved feed efficiency in females. Abdominal fat content was significantly less in males fed diets supplemented with additional methionine, whereas copper supplementation had no affect. No significant treatment effects on abdominal fat were observed in females.
TABLE 2. Analyzed amino acid composition of broiler diets1 Experiment Amino acid
1
2
Methionine Cystine TSAA Lysine Leucine Isoleucine Threonine Valine Arginine Glycine Serine Tryptophan
.351 .360 .711 1.063 1.820 .804 .758 .896 1.321 .869 .998 ND 2
.363 .353 .716 1.014 1.730 .818 .781 .977 1.293 .874 1.004 .242
1 Determined on one sample per diet and expressed on an "as fed" basis. 2
ND = Not determined.
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Corn, ground yellow Soybean meal, dehulled Fat, poultry Dicalcium phosphate (21.3% Ca, 18.7% P) Limestone, ground Salt Vitamin mix 1 Trace mineral mix2 Selenium premix 3 Bacitracin MD50 4 Monensin premix 5 DL-Methionine Calculated composition: ME, kcal/kg Protein, % Calcium, % Phosphorus, available, % Methionine, % Cystine, % TSAA, %
(ppm)
0 0 0 240 240 240
(%)
.72 .78 .84 .72 .78 .84
1,174 1,238 1,245 1,175 1,274 1,303
Males
(g/chick)
.0017 .13 .51
± 21 ± 21 abc 34 be : 17ab ± 29,bc
a
1,035 1,064 1,086 1,033 1,045 1,077 .07 .54 .91
± 24 ± 23 ± 13 ± 21 ± 17 ± 8
Females
BW gain (3 to 6 wk)
.008
.89
.0001
.459 ± .008 .481 ± .003 .472 ± .002 .435 ± .015 .483 ± .008 .500 ± .003
Males
(ppm)
0 0 0 240 240 240
(%)
.72 .78 .84 .72 .78 .84
.30 .003 .033
1,372+ 8fc
(g/chick)
1,093 1,088 1,100 1,100 1,097 1,122 .48 .34
+ 22 + 12 + 15 + 12 + 22 + 12
Females
BW gain (3 to 6 wk)
1,305 + 1 2 a 1,356 ± 17 u 1,349 ± l l b 1,380+ 15 u 1,362 ± 10 b
Males
.14 .07 .29
.485 + .014 .510 ± .005 .515 + .005 .513 + .012 .535 ± .015 .513 + .010
(g/g)
.31 .03 .98
.478 ± .481 + .493 + .498 ± .498 ± .508 ±
.00 .0 .00 .00 .00 .00
Females
Gain:feed ratio (3 to 6 wk) Males
Values within a column with no common superscripts are significantly different (P<.05).
Source of variation, pro babilities TSAA Cu TSAA X Cu
Added Cu
Treatment
.48 .64 .98
.478 + . .469 + . .478 + . .483 + . .472 + . .481 + .
TABLE 4. Effect (x ± SE) of dietary treatments on body weight gain, feed.gain ratio, and abdo
(g/g)
Females
Gain:feed ratio (3 to 6 wk)
Values within a column with no common superscripts are significantly different (P<.05).
TSAA
c
Source of variation, probabilities TSAA Cu TSAA X Cu
Added Cu
TSAA
Treatment
TABLE 3. Effect (x ± SE) of dietary treatments on body weight gain, feed-.gain ratio, and abdo
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SULFUR AMINO ACID REQUIREMENT
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TABLE 5. Effect (x + SE) of total sulfur amino acid levels on performance of each sex of broilers (data from two experiments combined) Gaimfeed ratio (3 to 6 wk)
BW gain (3 to 6 wk) TSAA
(%) .72 .78 .84
Males
Females
Males
(g/chick) 1,259 ± 9° 1,307 ± 9 a 1,317+ 10 a
1,065 : ab 1,073 : 10' 1,096 : 10 a
Females
Males
.484 + .005a .480 + .005a .489 ± .005a
1.90 ± .06a 1.71 + ,06b 1.68 ± 06 L
Females (% BW)
(g/g) .472 + .005° .501 ± .005a .500 ± ,005a
Abdominal fat (6 wk)
2.17 ± 06 a 1.99 ± 0 6 b 1.99+ .06b
a,bValues within a column with no common superscripts are significantly different (P<.05).
DISCUSSION
The results of these experiments demonstrate that the NRC (1984) value of .72% is inadequate as a minimum broiler requirement for TSAA from 3 to 6 wk of age for the strain of chickens used in the present study. Differences between responses to methionine supplementation observed in the two experiments may be related to differences in season of the year in which the experiments were conducted in curtain-sided houses. Analysis of the combined data, however, revealed significant improvement in all parameters (increased body weight gain, feed efficiency, and reduced abdominal fat) when the level of TSAA was increased from .72 to .78%. Although the response to methionine supplementation was generally less in females than in males, analysis of the combined data showed a significant increase in body weight gain and a significant reduction in abdominal fat per unit
of body weight for this sex by increasing the dietary level of TSAA. The data suggest that a value of .78% would be better as a minimum requirement of broiler chickens at this age than the currently recommended .72%. The results of this study also demonstrate that using only body weight gain and feed efficiency as the criteria for establishing a minimum requirement for TSAA for broiler production may be inadequate. In the second experiment, a significant reduction in abdominal fat was observed by methionine supplementation, even though no significant differences in body weight gain or feed efficiency were observed in the male broilers. Subjective observations of the feathering of the birds and feathers in the litter among pens were made, but no obvious differences in the treatments were observed. Inconsistent results were obtained with copper supplementation in the study, and body weight was significantly improved in males by copper supplementation in only one experiment. Likewise, in one experiment, copper supplementation significantly decreased abdominal fat and improved feed efficiency in females. Evidence for an interaction between copper supplementation and methionine requirement was observed for males in both experiments, as there was a significant interaction with body weight gain in the first experiment and feed efficiency in the second for these two dietary components. Analysis of the combined data from the two experiments, however, revealed no significant interactions between copper and TSAA for either sex. Thus these data with older broilers only weakly support the observations of Robbins and Baker (1980) and Wang et al. (1987) that copper supplementation increases the requirement of chicks for TSAA.
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When data from the two experiments were analyzed on a combined basis, significant (P< .05) increases in body weight gain and feed efficiency and a significant decrease in abdominal fat were observed in males by increasing TSAA level from .72 to .78% (Table 5). No further significant changes were seen by increasing the TSAA level to .84%. In females body gain was significantly higher at the highest TSAA supplementation level (.84%) than at the lowest level. The .78% or higher TSAA supplementation level resulted in a significant reduction in abdominal fat as a percentage of body weight. In the analysis of the combined data, no significant copper x TSAA interaction was observed for either sex.
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JENSEN ETAL. ACKNOWLEDGMENTS
The authors are indebted to the Degussa Corporation (Teterboro, NJ) for conducting the amino acid analyses of the basal diets. REFERENCES
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Anonymous, 1987. Nutritional Reports and Animal Nutrition. Degussa Corp., Teterboro, NJ. Jensen, L. S., andD. V. Maurice, 1979. Influence of sulfur amino acids on copper toxicity in chicks. J. Nutr. 109:91-97. National Research Council, 1984. Nutrient Requirements of Poultry. National Academy Press, Washington, DC. Patel, M. B., K. O. Bishawi, G. W. Nam, and J. McGinnis, 1980. Effect of drug additives and type of diet on methionine requirement for growth, feed efficiency, and feathering of broilers reared in floor pens. Poultry Sci. 59:2111-2120. Robbins, K. R., and D. H. Baker, 1980. Effect of sulfur
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