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Effect of Lysine and Methionine Supplementation of Low Protein Roaster Diets Fed After Six Weeks of Age
METABOLISM AND NUTRITION Effect of Lysine and Methionine Supplementation of Low Protein Roaster Diets Fed After Six Weeks of Age N.J.DAGHIR Department of Animal Sciences, American University of Beirut, Lebanon (Received for publication October 1, 1982)
1983 Poultry Science 62:1572-1575 INTRODUCTION The cost of p r o t e i n and energy c o m p o n e n t s used in t o d a y ' s commercial broiler diets m a k e u p a p p r o x i m a t e l y 90% of t o t a l feed cost. Decreasing dietary p r o t e i n w i t h o u t causing a reduction in performance can result in m o n e tary gains. The National Research Council ( N R C , 1977) r e c o m m e n d s a m i n i m u m p r o t e i n level of 18% for broilers from 6 t o 9 weeks of age with m e t h i o n i n e and lysine r e q u i r e m e n t s of .32 and .85%, respectively. Couch and R a y t o n ( 1 9 7 4 ) have previously r e p o r t e d t h a t t h e protein requirement is b e t w e e n 18 t o 20% with t h e need for m e t h i o n i n e s u p p l e m e n t a t i o n at t h e 20% protein level and m e t h i o n i n e and lysine s u p p l e m e n t a t i o n at t h e 18% level. Work c o n d u c t e d b y Twining et al. ( 1 9 7 8 ) showed t h a t m e a t birds reared for 59 d a y s and fed low p r o t e i n diets had lower b o d y weights t h a n those fed high' p r o t e i n diets. However, these workers used an energy level of 3400
1 Contribution from the Faculty of Agricultural and Food Sciences, American University of Beirut, as Journal No. 570B. This work was financially supported by the Lebanese National Council for Scientific Research.
kcal/kg r a t h e r t h a n 3 2 0 0 kcal/kg and did n o t equalize a m i n o acids t o t h e high protein diet. T h e same workers have previously (Twining et al, 1 9 7 3 ) s h o w n t h a t t h e m i n i m u m lysine r e q u i r e m e n t of roasters during t h e 7- t o 9-week growing period was .68% of t h e diet. T h o m a s et al. ( 1 9 7 7 ) , w h o also studied t h e lysine req u i r e m e n t of 7- t o 9-week-old sexed broilers, found t h a t t h e available lysine r e q u i r e m e n t for females was .64% for b o t h g r o w t h and feed conversion while for males it was .69% for gain and .66% for feed conversion. In t h e absence of a d e q u a t e m e t h i o n i n e in t h e diet, Plavnik and Bornstein ( 1 9 7 8 ) f o u n d t h a t broilers t e n d e d t o increase feed cons u m p t i o n in o r d e r t o maintain n o r m a l g r o w t h rate. Hulan and P r o u d f o o t ( 1 9 8 1 ) c o m p a r e d different d i e t a r y regimens for broilers reared t o roaster weight. A m o n g t h e three protein levels (14, 16, 18%) tested during t h e finisher period (50 t o 70 days), t h e 16% protein ( 3 3 0 0 kcal/ kg) diet resulted in o p t i m u m biological response and m o n e t a r y r e t u r n s . T h e purpose of this s t u d y was to evaluate t h e effects of feeding low protein diets supplemented with DL-methionine and L-lysine HCl o n feed c o n s u m p t i o n , b o d y weight gains, feed conversion, and carcass composition of
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ABSTRACT Three floor rearing experiments were conducted using male broilers to determine the extent to which the protein level of the diet can be reduced by supplementation with the amino acids methionine and lysine. Corn-soybean type diets were used and three protein levels (18, 15, and 12%) were tested. All rations were computer formulated and those containing 15 and 12% protein were supplemented with DL-methionine and L-Iysine HC1. Three replicate pens of about 50 males per pen were assigned to each treatment. Experimental diets were fed from 6 to 10 weeks of age in Experiment 1 and 6 to 9 weeks in Experiments 2 and 3. Birds were all group weighed at weekly intervals and feed consumption determined. Results obtained in Experiments 1 and 3 showed that neither body weight nor feed efficiency was reduced by feeding either 15 or 12% protein diets as long as these diets contained the National Research Council (NRC, 1977) recommended level of methionine and lysine. In Experiment 2 the 12% protein level depressed body weight and feed efficiency. Net returns over feed cost were highest with the 15% protein level in all three experiments. These results indicate that the NRC (1977) recommendation of 18% protein for 6- to 9-week-old broilers may be reduced with adequate amino acid supplementation. (Key words: roasters, protein requirement, methionine, lysine)
ROASTER DIETS roasters over 6 weeks of age. Net returns over feed cost were also calculated for each experiment.
MATERIALS AND METHODS
T h e three e x p e r i m e n t a l diets used were basically corn-soybean meal diets with n o animal protein s u p p l e m e n t s . Nonnutritive fiber was used in rations t o equalize energy. Rations
consisted of a control 18% protein diet supplem e n t e d w i t h .02% DL-methionine, a 1 5 % p r o t e i n diet with .07% D L - m e t h i o n i n e and .15% L-lysine HCl, and a 12% protein diet with . 1 5 % D L - m e t h i o n i n e and .36% L-lysine HCl. Feed was provided ad libitum and light was provided continously. T h e birds were weighed at t h e beginning of each e x p e r i m e n t and t h e n reweighed at weekly intervals. In E x p e r i m e n t 3, 5 birds were selected from each pen having individual weights equal t o t h e average weight of t h a t pen. T h e y were killed, dressed, and each cut into t w o equal halves and frozen for a period n o t exceeding 3 weeks. Analysis was d e t e r m i n e d o n each half using Association of Official Analytical Chemists ( 1 9 7 5 ) m e t h o d s for moisture, protein, fat, and ash. Data of all e x p e r i m e n t s were analyzed statistically b y analysis of variance according t o Snedecor and Cochran ( 1 9 7 6 ) and multiple comparisons were m a d e according t o D u n c a n ( 1 9 5 5 ) for differences a m o n g m e a n s . N e t r e t u r n s over feed cost were calculated for t h e roaster period using feed costs in Lebanese
TABLE 1. Composition of diets used % Protein Ingredients
18
15
12
(%) Yellow corn Soybean meal (49%) Soybean oil Non-nutritive fiber a Bone meal Limestone Salt Vitamin and trace mineral mix" DL-Methionine L-Lysine HCl Calculated analysis ME (kcal/kg) Crude protein (%) Methionine Methionine + Cystine Lysine Costs (LL/kg)c
60.00 25.71 5.60 4.20 3.20 .27 .50 .50 .02
3200 18
75.00 17.20 2.80 .27 3.26 .25 .50 .50 .07 .15 3200 15
.32 .60 .94 1.17
.34 .60 .85 1.06
80.00 10.40 2.53 2.04 3.28 .24 .50 .50 .15 .36 3200 12 .38 .60 .85 1.03
Alphacel, Nutritional Biochemicals Corporation, Cleveland, OH. The premix supplied the following per kilogram of complete feed: vitamin A, 11060 IU,; vitamin D 3 , 1510 IU,; vitamin E, 12 IU,; menadione sodium bisulfite, 2.8 mg; riboflavin, 10.5 mg; vitamin B n , 21 Mg; nicotinic acid, 53 mg; D-calcium pantothenate, 19 mg; folic acid, .87 mg; choline chloride, 658 mg; BHT, 125 mg; manganese, 80 mg; zinc 65 mg; iron, 90 mg; copper, 12 mg; iodine, 4.2 mg; cobalt, 3.6 mg; coccidiostat (monensin) 125 mg. LL, Lebanese pounds (one LL is approximately equivalent to US $.25).
Downloaded from http://ps.oxfordjournals.org/ at Albert R. Mann Library on December 15, 2014
Day-old male broiler chicks were raised in floor pens in a conventional broiler house and were given a commercial broiler starter (22.6% p r o t e i n , 3 0 5 0 kcal/kg) from day-old t o 3 weeks and a commercial broiler grower ( 1 9 . 8 % protein, 3 1 5 0 kcal/kg) from 3 t o 6 weeks of age. At this t i m e t h e y were divided into nine pens with 50 birds in each pen. Each of t h e diets shown in Table 1 was fed t o t h r e e pens for a period of 4 weeks in E x p e r i m e n t 1 and for 3 weeks in E x p e r i m e n t s 2 and 3. E x p e r i m e n t 1 was c o n d u c t e d in t h e fall ( O c t o b e r ) , Experim e n t 2 in winter ( J a n u a r y ) , and Experiment 3 in s u m m e r (August).
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pounds 2 per kilogram shown in Table 1 and market price of roaster in Lebanese pounds per kilogram live weight.
TABLE 2. Effect of protein level and amino acid supplementation on roaster performance (6- to 10week) during the fall (Experiment 1)
Results of Experiment 1, which was conducted in the fall, are presented in Table 2. There were no significant differences in either body weights or in feed efficiency among the three diets tested. The 15% protein diet supplemented with methionine and lysine gave the highest net returns over feed cost, followed by the 12% protein diet. Results of Experiment 2 (Table 3), which was conducted in the winter, show reduced gains at the 12% protein level and reduced feed efficiency (P<.05). Birds in this experiment showed a degree of compensation in feed intake, which improved gain with the 15% protein level but not with the 12% level. This is in agreement with Plavnik and Bornstein (1978) who showed that broilers during the finisher period tend to increase their feed consumption to maintain normal growth when amino acids are marginal or protein is limiting. Net returns over feed cost in Experiment 2 were also highest with the 15% protein diet, whereas the 12% diet in this experiment gave the lowest returns.
Body weight gain
Feed efficiency
(%)'
(g/bird)
(feed/ gain)
(LL/ bird) 2
18 15 12
1771 1813 1786
2.91 2.86 3.10
4.60 5.39 5.00
Results of Experiment 3, which was conducted in the summer, are shown in Table 4. Dietary protein level had no significant effect on either body weight gains or feed efficiency as was shown in experiment 1. Birds ate less in the summer and thus gained less, but as expected under our climatic conditions, the best feed efficiency occurred in this experiment. Net returns over feed cost also followed the same trend as in Experiment 1. Mortality was very low in all three experiments and, thus, was not influenced by protein level. Carcass composition data obtained in Experiment 3 are shown in Table 5. These results demonstrate that as the protein level decreased, there was a corresponding increase in carcass fat and a decrease in carcass moisture. The differences, however, were not statistically significant. Moran (1979) found that as the protein level of broiler finishing diets decreased, a greater degree of fat cover could be readily detected on the carcass. These results are also in agreement with those of Twining et al. (1978), who evaluated the effect of low protein diets on 2
One Lebanese pound is ca. US $.25.
1
See Table 1 for amino acid supplements.
2
LL, Lebanese pound.
TABLE 3. Effect of protein level and amino acid supplementation on roaster performance (6- to 9week) during the winter (Experiment 2)
Dietary protein
Body weight gam
Feed efficiency
Net returns over feed cost
(%)'
(g/bird)
(feed/ gain)
(LL/ bird)
18 15 12
1412 a 1413 a 1340b
2.87 a 3.13 a b 3.44 b
3.73 3.78 3.32
a ' b Means with different superscripts are significantly different (P<.05). 1
See Table 1 for amino acid supplements.
TABLE 4. Effect of protein level and amino acid supplementation on roaster performance (6- to 9week) during the summer (Experiment 3)
Dietary protein
Body weight gain
Feed efficiency
Net returns over feed cost
(%)'
(g/bird)
(feed/ gain)
(LL/ bird) 2
18 15 12
1252 1203 1213
2.42 2.47 2.63
3.95 4.08 3.98
1
See Table 1 for amino acid supplements.
2
LL, Lebanese pound.
Downloaded from http://ps.oxfordjournals.org/ at Albert R. Mann Library on December 15, 2014
Dietary protein
Net returns over feed cost
RESULTS AND DISCUSSION
ROASTER DIETS TABLE 5. Effect of protein level and amino acid supplementation on carcass composition of roasters at 9 weeks of age (Experiment 3)
Moisture
Protein
Fat
Ash
18 15 12
61.04 59.88 58.83
<%) 16.60 16.06 16.12
16.64 18.07 19.67
3.03 3.30 3.26
See Table 1 for amino acid supplements.
ACKNOWLEDGMENTS author
gratefully
acknowledges
the
Association of Official Analytical Chemists, 1975. Official Methods of Analysis. 12th ed. Assoc. Offic. Anal. Chem., Washington, DC. Couch, J. R., and J. K. Rayton, 1974. Amino acids and protein in broiler nutrition. Poultry Sci. 53:750-755. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1—42. Hulan, H. W., and F. G. Proudfoot, 1981. The effect of different protein levels in a three stage system on general performance of chickens reared to roaster weight. Poultry Sci. 60:172-178. Moran, E. T., 1979. Carcass quality changes with the broiler chicken after dietary protein restriction during the growing phase and finishing period compensatory growth. Poultry Sci. 58:1257— 1270. National Research Council, 1977. Nutrient Requirements of Domestic Animals. No. 1. Nutrient Requirements of Poultry. 7th ed. Natl. Acad. Sci., Washington, DC. Plavnik, Y., and S. Bomstein, 1978. The sparing action of inorganic sulfate on sulfur amino acid in practical broiler diets: replacement of some of the supplementary methionine in broiler finisher diets. Br. Poult. Sci. 19:159-167. Snedecor, G. W., and W. C. Cochran, 1976. Statistical Methods. 2th ed. Iowa State Univ. Press, Ames, IA. Thomas, O. P., P. V. Twining, and E. H. Bossard, 1977. The available lysine requirement of 7-9 week old sexed broiler chicks. Poultry Sci. 56:57-60. Twining, P. V., O. P. Thomas, and E. H. Bossard, 1978. The effect of diet and type of birds on the carcass composition of broilers at 28, 49, and 59 days of age. Poultry Sci. 57:492—497. Twining, P. V., O. P. Thomas, E. H. Bossard, and J. L. Nicholson, 1973. The available lysine requirement of 7-9 week old male broiler chicks. Poultry Sci. 52:2280-2286.
Downloaded from http://ps.oxfordjournals.org/ at Albert R. Mann Library on December 15, 2014
body composition of broilers at 28, 49, and 59 days of age and found that the low protein diets produced more carcass fat and less moisture than high protein diets. Results obtained in this study indicate that body weight gains are not significantly affected by reducing the protein level of the diet during the roaster growing period studied when these diets are adequately supplemented with methionine and lysine. However, it should be pointed out that in conventional broiler houses, seasonal effects can influence response to dietary protein changes as shown with constant dietary energy in these experiments. The results indicate, therefore, that the NRC (1977) recommendation of 18% protein for 6to 9-week-old broilers may be reduced by providing adequate amino acid supplementation.
The
assistance of Vahe Ashkarian, Fuad Fleifel, and Sinan Kaysi for their help in this study. REFERENCES
Dietary protein 1
1
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1983 Poultry Science 62:1572-1575 INTRODUCTION The cost of p r o t e i n and energy c o m p o n e n t s used in t o d a y ' s commercial broiler diets m a k e u p a p p r o x i m a t e l y 90% of t o t a l feed cost. Decreasing dietary p r o t e i n w i t h o u t causing a reduction in performance can result in m o n e tary gains. The National Research Council ( N R C , 1977) r e c o m m e n d s a m i n i m u m p r o t e i n level of 18% for broilers from 6 t o 9 weeks of age with m e t h i o n i n e and lysine r e q u i r e m e n t s of .32 and .85%, respectively. Couch and R a y t o n ( 1 9 7 4 ) have previously r e p o r t e d t h a t t h e protein requirement is b e t w e e n 18 t o 20% with t h e need for m e t h i o n i n e s u p p l e m e n t a t i o n at t h e 20% protein level and m e t h i o n i n e and lysine s u p p l e m e n t a t i o n at t h e 18% level. Work c o n d u c t e d b y Twining et al. ( 1 9 7 8 ) showed t h a t m e a t birds reared for 59 d a y s and fed low p r o t e i n diets had lower b o d y weights t h a n those fed high' p r o t e i n diets. However, these workers used an energy level of 3400
1 Contribution from the Faculty of Agricultural and Food Sciences, American University of Beirut, as Journal No. 570B. This work was financially supported by the Lebanese National Council for Scientific Research.
kcal/kg r a t h e r t h a n 3 2 0 0 kcal/kg and did n o t equalize a m i n o acids t o t h e high protein diet. T h e same workers have previously (Twining et al, 1 9 7 3 ) s h o w n t h a t t h e m i n i m u m lysine r e q u i r e m e n t of roasters during t h e 7- t o 9-week growing period was .68% of t h e diet. T h o m a s et al. ( 1 9 7 7 ) , w h o also studied t h e lysine req u i r e m e n t of 7- t o 9-week-old sexed broilers, found t h a t t h e available lysine r e q u i r e m e n t for females was .64% for b o t h g r o w t h and feed conversion while for males it was .69% for gain and .66% for feed conversion. In t h e absence of a d e q u a t e m e t h i o n i n e in t h e diet, Plavnik and Bornstein ( 1 9 7 8 ) f o u n d t h a t broilers t e n d e d t o increase feed cons u m p t i o n in o r d e r t o maintain n o r m a l g r o w t h rate. Hulan and P r o u d f o o t ( 1 9 8 1 ) c o m p a r e d different d i e t a r y regimens for broilers reared t o roaster weight. A m o n g t h e three protein levels (14, 16, 18%) tested during t h e finisher period (50 t o 70 days), t h e 16% protein ( 3 3 0 0 kcal/ kg) diet resulted in o p t i m u m biological response and m o n e t a r y r e t u r n s . T h e purpose of this s t u d y was to evaluate t h e effects of feeding low protein diets supplemented with DL-methionine and L-lysine HCl o n feed c o n s u m p t i o n , b o d y weight gains, feed conversion, and carcass composition of
1572
Downloaded from http://ps.oxfordjournals.org/ at Albert R. Mann Library on December 15, 2014
ABSTRACT Three floor rearing experiments were conducted using male broilers to determine the extent to which the protein level of the diet can be reduced by supplementation with the amino acids methionine and lysine. Corn-soybean type diets were used and three protein levels (18, 15, and 12%) were tested. All rations were computer formulated and those containing 15 and 12% protein were supplemented with DL-methionine and L-Iysine HC1. Three replicate pens of about 50 males per pen were assigned to each treatment. Experimental diets were fed from 6 to 10 weeks of age in Experiment 1 and 6 to 9 weeks in Experiments 2 and 3. Birds were all group weighed at weekly intervals and feed consumption determined. Results obtained in Experiments 1 and 3 showed that neither body weight nor feed efficiency was reduced by feeding either 15 or 12% protein diets as long as these diets contained the National Research Council (NRC, 1977) recommended level of methionine and lysine. In Experiment 2 the 12% protein level depressed body weight and feed efficiency. Net returns over feed cost were highest with the 15% protein level in all three experiments. These results indicate that the NRC (1977) recommendation of 18% protein for 6- to 9-week-old broilers may be reduced with adequate amino acid supplementation. (Key words: roasters, protein requirement, methionine, lysine)
ROASTER DIETS roasters over 6 weeks of age. Net returns over feed cost were also calculated for each experiment.
MATERIALS AND METHODS
T h e three e x p e r i m e n t a l diets used were basically corn-soybean meal diets with n o animal protein s u p p l e m e n t s . Nonnutritive fiber was used in rations t o equalize energy. Rations
consisted of a control 18% protein diet supplem e n t e d w i t h .02% DL-methionine, a 1 5 % p r o t e i n diet with .07% D L - m e t h i o n i n e and .15% L-lysine HCl, and a 12% protein diet with . 1 5 % D L - m e t h i o n i n e and .36% L-lysine HCl. Feed was provided ad libitum and light was provided continously. T h e birds were weighed at t h e beginning of each e x p e r i m e n t and t h e n reweighed at weekly intervals. In E x p e r i m e n t 3, 5 birds were selected from each pen having individual weights equal t o t h e average weight of t h a t pen. T h e y were killed, dressed, and each cut into t w o equal halves and frozen for a period n o t exceeding 3 weeks. Analysis was d e t e r m i n e d o n each half using Association of Official Analytical Chemists ( 1 9 7 5 ) m e t h o d s for moisture, protein, fat, and ash. Data of all e x p e r i m e n t s were analyzed statistically b y analysis of variance according t o Snedecor and Cochran ( 1 9 7 6 ) and multiple comparisons were m a d e according t o D u n c a n ( 1 9 5 5 ) for differences a m o n g m e a n s . N e t r e t u r n s over feed cost were calculated for t h e roaster period using feed costs in Lebanese
TABLE 1. Composition of diets used % Protein Ingredients
18
15
12
(%) Yellow corn Soybean meal (49%) Soybean oil Non-nutritive fiber a Bone meal Limestone Salt Vitamin and trace mineral mix" DL-Methionine L-Lysine HCl Calculated analysis ME (kcal/kg) Crude protein (%) Methionine Methionine + Cystine Lysine Costs (LL/kg)c
60.00 25.71 5.60 4.20 3.20 .27 .50 .50 .02
3200 18
75.00 17.20 2.80 .27 3.26 .25 .50 .50 .07 .15 3200 15
.32 .60 .94 1.17
.34 .60 .85 1.06
80.00 10.40 2.53 2.04 3.28 .24 .50 .50 .15 .36 3200 12 .38 .60 .85 1.03
Alphacel, Nutritional Biochemicals Corporation, Cleveland, OH. The premix supplied the following per kilogram of complete feed: vitamin A, 11060 IU,; vitamin D 3 , 1510 IU,; vitamin E, 12 IU,; menadione sodium bisulfite, 2.8 mg; riboflavin, 10.5 mg; vitamin B n , 21 Mg; nicotinic acid, 53 mg; D-calcium pantothenate, 19 mg; folic acid, .87 mg; choline chloride, 658 mg; BHT, 125 mg; manganese, 80 mg; zinc 65 mg; iron, 90 mg; copper, 12 mg; iodine, 4.2 mg; cobalt, 3.6 mg; coccidiostat (monensin) 125 mg. LL, Lebanese pounds (one LL is approximately equivalent to US $.25).
Downloaded from http://ps.oxfordjournals.org/ at Albert R. Mann Library on December 15, 2014
Day-old male broiler chicks were raised in floor pens in a conventional broiler house and were given a commercial broiler starter (22.6% p r o t e i n , 3 0 5 0 kcal/kg) from day-old t o 3 weeks and a commercial broiler grower ( 1 9 . 8 % protein, 3 1 5 0 kcal/kg) from 3 t o 6 weeks of age. At this t i m e t h e y were divided into nine pens with 50 birds in each pen. Each of t h e diets shown in Table 1 was fed t o t h r e e pens for a period of 4 weeks in E x p e r i m e n t 1 and for 3 weeks in E x p e r i m e n t s 2 and 3. E x p e r i m e n t 1 was c o n d u c t e d in t h e fall ( O c t o b e r ) , Experim e n t 2 in winter ( J a n u a r y ) , and Experiment 3 in s u m m e r (August).
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pounds 2 per kilogram shown in Table 1 and market price of roaster in Lebanese pounds per kilogram live weight.
TABLE 2. Effect of protein level and amino acid supplementation on roaster performance (6- to 10week) during the fall (Experiment 1)
Results of Experiment 1, which was conducted in the fall, are presented in Table 2. There were no significant differences in either body weights or in feed efficiency among the three diets tested. The 15% protein diet supplemented with methionine and lysine gave the highest net returns over feed cost, followed by the 12% protein diet. Results of Experiment 2 (Table 3), which was conducted in the winter, show reduced gains at the 12% protein level and reduced feed efficiency (P<.05). Birds in this experiment showed a degree of compensation in feed intake, which improved gain with the 15% protein level but not with the 12% level. This is in agreement with Plavnik and Bornstein (1978) who showed that broilers during the finisher period tend to increase their feed consumption to maintain normal growth when amino acids are marginal or protein is limiting. Net returns over feed cost in Experiment 2 were also highest with the 15% protein diet, whereas the 12% diet in this experiment gave the lowest returns.
Body weight gain
Feed efficiency
(%)'
(g/bird)
(feed/ gain)
(LL/ bird) 2
18 15 12
1771 1813 1786
2.91 2.86 3.10
4.60 5.39 5.00
Results of Experiment 3, which was conducted in the summer, are shown in Table 4. Dietary protein level had no significant effect on either body weight gains or feed efficiency as was shown in experiment 1. Birds ate less in the summer and thus gained less, but as expected under our climatic conditions, the best feed efficiency occurred in this experiment. Net returns over feed cost also followed the same trend as in Experiment 1. Mortality was very low in all three experiments and, thus, was not influenced by protein level. Carcass composition data obtained in Experiment 3 are shown in Table 5. These results demonstrate that as the protein level decreased, there was a corresponding increase in carcass fat and a decrease in carcass moisture. The differences, however, were not statistically significant. Moran (1979) found that as the protein level of broiler finishing diets decreased, a greater degree of fat cover could be readily detected on the carcass. These results are also in agreement with those of Twining et al. (1978), who evaluated the effect of low protein diets on 2
One Lebanese pound is ca. US $.25.
1
See Table 1 for amino acid supplements.
2
LL, Lebanese pound.
TABLE 3. Effect of protein level and amino acid supplementation on roaster performance (6- to 9week) during the winter (Experiment 2)
Dietary protein
Body weight gam
Feed efficiency
Net returns over feed cost
(%)'
(g/bird)
(feed/ gain)
(LL/ bird)
18 15 12
1412 a 1413 a 1340b
2.87 a 3.13 a b 3.44 b
3.73 3.78 3.32
a ' b Means with different superscripts are significantly different (P<.05). 1
See Table 1 for amino acid supplements.
TABLE 4. Effect of protein level and amino acid supplementation on roaster performance (6- to 9week) during the summer (Experiment 3)
Dietary protein
Body weight gain
Feed efficiency
Net returns over feed cost
(%)'
(g/bird)
(feed/ gain)
(LL/ bird) 2
18 15 12
1252 1203 1213
2.42 2.47 2.63
3.95 4.08 3.98
1
See Table 1 for amino acid supplements.
2
LL, Lebanese pound.
Downloaded from http://ps.oxfordjournals.org/ at Albert R. Mann Library on December 15, 2014
Dietary protein
Net returns over feed cost
RESULTS AND DISCUSSION
ROASTER DIETS TABLE 5. Effect of protein level and amino acid supplementation on carcass composition of roasters at 9 weeks of age (Experiment 3)
Moisture
Protein
Fat
Ash
18 15 12
61.04 59.88 58.83
<%) 16.60 16.06 16.12
16.64 18.07 19.67
3.03 3.30 3.26
See Table 1 for amino acid supplements.
ACKNOWLEDGMENTS author
gratefully
acknowledges
the
Association of Official Analytical Chemists, 1975. Official Methods of Analysis. 12th ed. Assoc. Offic. Anal. Chem., Washington, DC. Couch, J. R., and J. K. Rayton, 1974. Amino acids and protein in broiler nutrition. Poultry Sci. 53:750-755. Duncan, D. B., 1955. Multiple range and multiple F tests. Biometrics 11:1—42. Hulan, H. W., and F. G. Proudfoot, 1981. The effect of different protein levels in a three stage system on general performance of chickens reared to roaster weight. Poultry Sci. 60:172-178. Moran, E. T., 1979. Carcass quality changes with the broiler chicken after dietary protein restriction during the growing phase and finishing period compensatory growth. Poultry Sci. 58:1257— 1270. National Research Council, 1977. Nutrient Requirements of Domestic Animals. No. 1. Nutrient Requirements of Poultry. 7th ed. Natl. Acad. Sci., Washington, DC. Plavnik, Y., and S. Bomstein, 1978. The sparing action of inorganic sulfate on sulfur amino acid in practical broiler diets: replacement of some of the supplementary methionine in broiler finisher diets. Br. Poult. Sci. 19:159-167. Snedecor, G. W., and W. C. Cochran, 1976. Statistical Methods. 2th ed. Iowa State Univ. Press, Ames, IA. Thomas, O. P., P. V. Twining, and E. H. Bossard, 1977. The available lysine requirement of 7-9 week old sexed broiler chicks. Poultry Sci. 56:57-60. Twining, P. V., O. P. Thomas, and E. H. Bossard, 1978. The effect of diet and type of birds on the carcass composition of broilers at 28, 49, and 59 days of age. Poultry Sci. 57:492—497. Twining, P. V., O. P. Thomas, E. H. Bossard, and J. L. Nicholson, 1973. The available lysine requirement of 7-9 week old male broiler chicks. Poultry Sci. 52:2280-2286.
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body composition of broilers at 28, 49, and 59 days of age and found that the low protein diets produced more carcass fat and less moisture than high protein diets. Results obtained in this study indicate that body weight gains are not significantly affected by reducing the protein level of the diet during the roaster growing period studied when these diets are adequately supplemented with methionine and lysine. However, it should be pointed out that in conventional broiler houses, seasonal effects can influence response to dietary protein changes as shown with constant dietary energy in these experiments. The results indicate, therefore, that the NRC (1977) recommendation of 18% protein for 6to 9-week-old broilers may be reduced by providing adequate amino acid supplementation.
The
assistance of Vahe Ashkarian, Fuad Fleifel, and Sinan Kaysi for their help in this study. REFERENCES
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