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Amino Acid Supplementation of Low-Protein Broiler Diets: 1. Glutamic Acid and Indispensable Amino Acid Supplementation
01999Applied PoulIq Science, Inc
ACIDSUPPLEMENTATION OF LOW=PROTEIN BROILER DIETS: 1. GLUTAMIC ACIDAND INDISPENSABLE AMINO ACIDSUPPLEMENTATION AMINO
Primarv Audience: Nutritionists. Researchers
I
formulation on a dgestible amino acid basis, DESCRIPTION OF PROBLEMand applicationof an ideal amino acid concept The most limiting dietary amino acids are available to the poultry industry as dietary supplements, allowing the opportunity to accurately meet the amino acid needs of the
1
To whom correspondence should be addressed
[l] m& result in crude protein (CP) levels much lower than those listed by the NRC [2]. Animals cannot convert excess amino acids into body protein, in fact, an oversupply of
Downloaded from http://japr.oxfordjournals.org/ at D H Hill Library - Acquis S on March 11, 2015
B. J. KERR' and M.T.KIDD Nuti-Quest, Inc., 1400 Elbridge Payne R o d Suite 110, Chestefleld MO 63017 Phone: (636)537-4057 F M : (636)532-1710 E-mail: [email protected]
Research Report KERR and KIDD and has been shown to depress performance, leading to inefficient and uneconomical meat production [3,4]. In addition, excessive protein or amino acid consumption leads to increased nitrogen excretion [5, 61. The purpose of the following experiment was to feed broilers reduced CP, amino acidsupplemented diets and evaluate the impact of dispensable and indispensable amino acid (IDAA) supplementation on bird performance and carcass characteristics.
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MATERIALS AND METHODS One-day-old male Ross x Ross broilers were allocated to 50 floor pens layered with new pine shavings. Each pen consisted of 120 broilers with three tube feeders and two bell waterers in pens that measured 3.66 x 3.05 m (0.093m2 floor space per bird). All broilers consumed feed and water ad libitum and were reared on continuous incandescent lighting. From Day 1 to 14 all birds were fed a diet containing corn, soybean meal, and meat and bone meal consisting of 3140 kcal ME/kg, 21.5% CP, 0.93% TSAA, and 1.22%total Lys. From Day 14 to 28 all birds were fed a similarly composed diet consisting of 3160 kcal ME/kg, 19%CP, 0.91% TSAA, and 1.08%Lys. Corn, soybean meal, meat and bone meal, and rice bran were analyzed for CP and amino acid content prior to diet formulation to assure accurate amino acid content. Dietary treatments were also analyzed for amino acids and Cl? Crude protein was calculated as nitrogen (N) X 6.25, amino acid concentrations determined following acid hydrolysis, B p concentration following alkaline hydrolysis, and Met and C y s following performic acid oxidation [q.True digestibility coefficients obtained from published tables [2] were applied to the analyzed amino acid levels in each ingredient to formulate diets on a true digestible amino acid basis. The Illinois Digestible Ideal Amino Acid profile was applied in diet formulation to ensure IDAA adequacy [l]. Ten dietary treatments were replicated five times (600 birddtreatment) in a randomized complete block design. Diet compositions for the finisher (Day 28 to 42) and withdrawal (Day 42 to 52) time periods are presented in Tables 1 and 2, respectively. Finisher diets were formulated to contain 3245 kcal ME kg-', with the digestible Lys calculated to be 0.94%
Downloaded from http://japr.oxfordjournals.org/ at D H Hill Library - Acquis S on March 11, 2015
(0.29%/1000 kcal kg-'). Withdrawal diets also contained 3245 kcal ME kgl, but digestible Lys content was lowered t o 0.84% (0.259%/1000kcal kg-l). The positive control finisher diet contained 19%CP, while the positive control withdrawal diet contained 18% CP.All other diets had CP levels reduced from these initial levels. In addition to meeting the estimated digestible amino acid requirement, all diets were formulated to meet a digestible Cys ratio [l].Treatment 1 was formulated to reflect typical diets utilized in industry, while Treatments 2,3, and 4 were reduced in CP by 2,4, and 6%, respectively. Treatments 5 6 , and 7 were similar to Treatments 2,3, and 4 except that 1% Glu was added as a dispensable amino acid nitrogen source. Treatments 8,9, and 10 were similar to Treatments 5,6, and 7 except that IDAA were supplemented according to an ideal amino acid pattern. All amino acids were added at the expense of corn. Pen BW were obtained on Days 28 and 52 to determine BW gain and feed conversion for the interim time period. Mortality was monitored throughout the experiment. On Day 52, nine birds/pen that were close to the pen average and had no visible signs of abnormalities were randomly chosen for processing. Feed was withdrawn for 12 hr prior to the birds being processed at a pilot processing laboratory. Buds were weighed at the poultry farm on Day 53, transported in coops (less than 1 km) to the processing plant, stunned with an electric knife, bled for 90 sec via severing of the jugular vein, scalded for 2 min, and defeathered in a rotary picker. Eviscera and abdominal fat were removed manually. The abdominal fat was weighed and birds were placed in an ice bath for 12 hr. Carcass parameters measured were live weight, chill weight, Pectoralis major and minor weq$t, thigh meat weight (skinned and deboned), drumstick meat weight (skinned and deboned), and wing weight. Data were analyzed using GeneraI Linear Models of SAS [8], using the pen as the experimental unit for all analysis. All percentage data were subjected to square root transformation prior to analysis. This transformation did not alter statistical interpretation; therefore data are presented as actual percentages. Statements of statistical si@icance are based on P 4.05.
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Supplementation of IDAA to the diets RESULTS AND DISCUSSIONalready containing Glu and reduced in CP by four or six percentage units improved BW gain, but failed to improve gains to the level achieved by birds fed the positive control diet. Supplementation of IDAA alleviated the reduction in feed intake due to Glu supplementation in the diet reduced in CP by six percentage units. The reduced feed conversion noted in diets reduced in CP by four percentage units (Treatments 3 and 6) was improved by IDAA + Glu supplementation (Treatment 9) to a level similar to that of birds fed the positive control diet. Even though daily BW gain and feed conversion improved in birds fed the treatment reduced in CP by six percentage units with IDAA + Glu supplementation compared to birds fed the unsupplemented or Glu-supplemented treatments (Treatments4 and 7, respectively), their performance was not equivalent to that of birds fed the positive control diet. Several studies indicate that birds do not perform as well on low-CP, amino acid-supplemented diets as on higher CP diets [9, 10, 11, 21,221; while other studies suggest that similar performance can be achieved [5, 15, 16, 23, 24, 25, 261. A limitation of this experiment was that IDAA were not tested in the absence of Glu so that IDAA supplementation could be evaluated independently. Dietary treatment had no effect on chick livability. The effects of dietary treatments on processing live weight reflect the results obtained on BW. Percentage chilled carcass weight was reduced due to a reduction in dietary CP by four or six percentage units when no amino acids were supplemented. Supplementation of Glu to the reduced CP treatments did not affect carcass yield. Supplementation of IDAA + Glu to the low-CP treatments, either with or without Glu, improved carcass yield to a level similar to that of birds fed the positive control diet. Percentage abdominal fat was unaffected when dietary CP levels were reduced by two percentage units, regardless of amino acid supplementation (Treatments 2, 5, and 8). This might be expectedbecause dietary amino acid levels were near recommended levels [2]. Further reductions in CP, without supplemental Glu or IDAA + Glu (lkeatments 3 and 4), resulted in increased abdominal fat. Supplementation of Glu to the diets reduced in CP by
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Analysis of the mixed diets yielded results in close agreement to the calculated composition (Tables 1 and 2). Performance and processing results of individual treatments are presented in Table 3. Initial BW at Day 28 did not differ due to dietary treatment. Reduction of CP by two percentage units without Glu or IDAA + Glu supplementation (Treatment 2) had no impact on daily BW gain or feed conversion compared to birds fed the positive control diet. However, further reductions in CP (Treatments3 and 4) caused a reduction in BW gain and feed conversion. Reduced CP diets without amino acid supplementationhad little effect on feed intake, although birds fed Treatment 4 exhibited lower feed intake than birds fed Treatments 1,2, or 3. It was not surprisiig that buds fed the treatment reduced in CP by two percentage units had BW similar to birds fed the high protein treatment, since this level of CP reduction results in amino acid levels being relatively close to current recommendations [2] (Tables 1 and 2). That small reductions in dietary CP have little effect on performance has been shown by others [9,10, 111. As dietary levels of CP are further reduced, other IDAA may become limiting and result in reduced performance [9,10,12]. Addition of 1% Glu to the low CP treatments numerically reduced daily BW gains compared to buds fed the unsupplemented diets, possibly due to minor reductions in feed intake. Feed intake was reduced, however, in birds fed the lowest CP treatment with Glu supplementation (Treatment 7). Although Glu is an excellent source of nonspecific N [13], and IDAA are poor sources of nonspecific N [141, the response of broilers to diets containing supplemental Glu varies. Supplementation of Glu to reduced-CP diets has yielded improvements in gain [15] and feed conversion [15, 16, 1 7 . In contrast, Leclercq et al. [18] and Deschepper and de Groote [5] have reported little effect of Glu supplementation on chick performance. The impact of supplemental Glu on feed intake is also unclear. Leclercq et al. [18] showed no effect of Glu on feed consumption, while negative effects of Glu on feed intake have been reported by others [5, 191. Ando et al. [20]noted negative effects of Glu on feed intake, but only when Glu supplementationwas 6% of the diet.
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CONCLUSIONS AND APPLICATIONS 1. Feeding reduced CP diets without amino acid supplementation severely reduced broiler performance and carcass meat yield. 2. Supplementation of 1% Glu exerted no positive effects on bird performance or carcass characteristics and appeared to reduce feed intake, resulting in reduced weight gains. 3. Supplementation of indispensable amino acids according to an ideal amino acid pattern improved broiler performance and carcass meat yield compared to birds fed unsupplemented or Glu-supplemented diets, but failed to completely alleviate some of tht: depressed performance and carcass parameters at the lowest level of dietary CP.
REFERENCES AND NOTES 1. Baker, D.H., 1994. Ideal amino acid profile for maximal protein accretion and minimal nitrogen excretion in m n e a n d poultry. Pages 134-139 in: Proc. Cornel1 Nutr. Conf., Rochester, NY. 2. National Research Council, 1994. Nutrient Reuirements of Poult 9th Rev. Edition. Natl. Acad. $ r e s , Washington, D?? 3. Waldroup, P.W., RJ.Mitchell, J.R Payne, and KR Haze%1976.Performance of chicks fed diets formu-
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lated to minimize excess levels of essential amino acids. Poultry Sci. 55:243-253. 4. Baker, D.H. and RA. Easter, 1976. Soy prot8:in as a source of amino acids for nonruminant animals.
Pages %9-976 in: World Soybean Research. L.E. Hill, ed. Interstate Printers and Publishers, Dandle, IL.
5. Deschepper, K. and G. de Groote, 1995. Effecl of dietary protein, essential and nonessential amino acids on the performance and carcass compositian of male broiler chickens. Br. Poultry Sci. W229-245.
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six percentage units, supplementation of IDAA + Glu improved the yield of I! majclr, but failed to improve it to the level achieved by birds fed the positive control diet. Suppkmentation of IDAA + Glu to the diet reduced in CP by six percentage units improved the yield of R minor to a level equivalent to birth fed the positive control. Except for the yield of Rmajor of birds fed Treatment 10, supplementation of IDAA + Glu to all the reduct:d CP diets resulted in R major and R mimr yields similar to those of birds fed the positive control diet. Research indicates that dietary CP level has no impact on breast meat yield when crystalline amino acids are supplemented to the low-CP diet [19, 24, 251. [n addition, Summers et ai. [28] and Leclercq er al. [18] reported that total carcass protein content was equivalent between birds fcd high-CP or low-CP, amino acid-supplemented diets. In contrast, Fancher and Jensen [9] and Moran et al. [12] reported that broilers fed low-CP, amino acid-supplemented diets hiid reduced breast meat yields. Yields of deboned thigh meat, deboncd drumstick meat, and whole wings were unaffected by dietary treatment. Similar results have been reported by Kidd et ai. [24], while Moran et al. [12] noted slight differences in thigh yields due to dietary protein level.
four and six percentage units had no effect on percentage abdominal fat. Supplementation of IDAA + Glu to birds fed the diets reduced in CP by six percentage units resulted in abdominal fat levels similar to those of birds fed the positive control. It has been shown that Glu may [9, 10, 19, 271 or may not [15]affect body fat, depending upon the type of diet (51 or broiler genetics used [18]. Increased abdominal fat in broilers fed low-CP, amino acid-supplemented diets has been reported [lo, 12, 21, 241. Inconsistency in amount of body fat may be attributable to the dietary Thr level as recent research suggests that adequate levels of dietary Thr may minimize carcass fatness [23]. Lowering dietary CP by two percentage units (Treatments 2, 5, and 8) did not affect R major or R minor yields. Further reductions in CP (Treatments 3 and 4) reduced R major and f? minor yields. Supplementation of Glu had no effect on R major or R minor yields. This is in agreement with past research [5,15, 18,191 demonstratingno effect of dispensable amino acids on carcass protein deposition. Supplementation of IDAA + Glu to the diet reduced in CP by four percentage units produced only numerical improvements in Rmajor and Rminor yields, each of which were similar to birds fed the positive control diet. In the treatment reduced in CP by
Research Report KERR and KIDD 6. Kerr, BJ., 1995. Nutritional Strategies for Waste Reduction-Management:Nitrogen. Pages 47-68 in: New Horizons in Animal Nutrition and Health (November), Raleigh, NC. 7. Association of OMclal Analytical Chemists, 1984. Official Methods of Analysis. 14th Edition. Assn. Offic. Anal. Chemists, Washington, DC. 8. SASInstitute, 1985. SAWSTATGuide for Personal Computers. Version 6 Edition. SAS Institute, Inc., Cary, NC.
9. Fancher, B.I. and LS.Jensen, 1989. Influence on performanceof 3 to 6-week-oldbroilers of varying dietary protein contentswith supplementationof essential amino acid requirements.Poultry Sci. 68.113-123.
18. Leclercq, B., A.M. Chagneau, T. Cochard, and J. Khoury, 1994. Comparative responses of genetically lean and fat chickens to me, arginine, and non-essential amino acid sup ly. ?Growth and body composition. Br. Poultry Sci. &:687496.
19. Huyghebaert, G. and M. Pack, 1996. Effects of dietary protein content, addition of nonessential amino acids, and dietary methionine to cysteine balance on responses to dietary sulphur-containing amino acids in broilers. Br. Poultry Sci. 37623-639. 20. Ando, M., H. Hayakawe, and S. HUlkuro, 1989. Effects of dietary arginine, glutamic acid, chlorine, and magnesium on the me requirement for starting chicks. Japan. Poultry Sci. %&l2-308.
21. Skinner, J.T., A L In16 and P.W. Waldroup, 1991. Effects of dietary amino acid levels on performance and carcass com osition of broilers 42 to 49 days of age. Poultry s i . 70:1223-1230.
11. Holsheimer, J.P. and W.M.M.A. Janssen, 1991. Limiting amino acids in low rotein maize-soyabean meal diets fed to broiler chicks from 3 to 7 weeks of age. Br. Poultry Sci. 32151-158.
22. Fancher, B.I. and LS. Jensen, 1989. Dietary protein level and essential amino acid content: Influence upon female broiler rformance during the grower period. Poultry Sci. 68:&908.
12. MOT ET., Jr., RD. Busbong, and S.F. Bilglli, 1992. Reducing dietary crude protein for broilers while satistjmg amino acid requirements by leastcost formulation: Live performance, litter composition, and yield of fast-food carcass cuts at 6 weeks. Poultry Sci. 71:1687-1694,
23. Kidd, M.T. and B.J. Kerr, 1997. Threonine responses in commercial broilers at 30 to 42 days. J. Appl. Poultry Res. 6362-367.
13. Featherston, W.R, 1976. Adequacy of glutamic acid $thesis by the chick for maximal growth. Poultry Sci. 5 24794480.
14. Allen, N.K. and D.H. Baker, 1974. Quantitative evaluation of nonspecific nitrogen sources for the growing chick. Poultry Sci. 53:258-264.
15. Moran, ET., Jr. and H.L Stilborn, 1996.Effect of glutamicacid on broilers given submarginal crude protein wth adequate essential amino acids using feeds high and low in potassium.Poultry Sci. 75120-129. 16.Han, Y.,H. Sudd, C.M. Parsons,and D.H. Baker, 1992. Amino acid fortificationof a low-protein corn and soybean meal diet for chicks. Poultry Sci. 71:1168-1178. 17. Parr,J.F. and J.D. Summers,1991.The effect of minimizing amino acid excesses in broiler diets. Poultry Sci. 70:1540-1549.
24. Kidd, M.T., BJ. Kerr, J.D. Firman, and S.D. B o k g , 1996. Growth and carcass characteristics of broilers fed low- rotein, threonine-supplementeddiets. J. Appl. Poultry l e s . 5:180-190. 25. Holsheimer, J.P., P.F.G. Vereuken, and J.B. Schuttc, 1994. Response of broiler chicks to threoninesup lemented diets to 4 weeks of age. Br. Poultry Sci. 35:&1-562. 26. Stilborn, H.L and P.W. Waldroup, 1989. Utilization of low- rotein grower diets for broiler chickens. Poultry Sci. &(Suppl):142 (Abs). 27. Edmonds, M.S., C.M. Parsons,and D.H. Baker, 1985. Limiting amino acids in low- rotein corn-soybean meal diets fed to growing chicks. Foultry Sci. 64:15191526. 28. Sumnets, J.D., D. Sprall, and J.L Atkinson, 1992. Broiler weight gain and carcass composition when fed diets vaIying in amino acid balance, dietary energy, and protein level. Poultry Sci. 71:26>273.
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10. Fancber, B.I. and LS.Jensen, 1989. Male broiler performance during the starting and growing periods as affected by dieta protein, essential amino acids, and potassium levels. ;4bultry Sci. 68:1385-1395.
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ACIDSUPPLEMENTATION OF LOW=PROTEIN BROILER DIETS: 1. GLUTAMIC ACIDAND INDISPENSABLE AMINO ACIDSUPPLEMENTATION AMINO
Primarv Audience: Nutritionists. Researchers
I
formulation on a dgestible amino acid basis, DESCRIPTION OF PROBLEMand applicationof an ideal amino acid concept The most limiting dietary amino acids are available to the poultry industry as dietary supplements, allowing the opportunity to accurately meet the amino acid needs of the
1
To whom correspondence should be addressed
[l] m& result in crude protein (CP) levels much lower than those listed by the NRC [2]. Animals cannot convert excess amino acids into body protein, in fact, an oversupply of
Downloaded from http://japr.oxfordjournals.org/ at D H Hill Library - Acquis S on March 11, 2015
B. J. KERR' and M.T.KIDD Nuti-Quest, Inc., 1400 Elbridge Payne R o d Suite 110, Chestefleld MO 63017 Phone: (636)537-4057 F M : (636)532-1710 E-mail: [email protected]
Research Report KERR and KIDD and has been shown to depress performance, leading to inefficient and uneconomical meat production [3,4]. In addition, excessive protein or amino acid consumption leads to increased nitrogen excretion [5, 61. The purpose of the following experiment was to feed broilers reduced CP, amino acidsupplemented diets and evaluate the impact of dispensable and indispensable amino acid (IDAA) supplementation on bird performance and carcass characteristics.
299
MATERIALS AND METHODS One-day-old male Ross x Ross broilers were allocated to 50 floor pens layered with new pine shavings. Each pen consisted of 120 broilers with three tube feeders and two bell waterers in pens that measured 3.66 x 3.05 m (0.093m2 floor space per bird). All broilers consumed feed and water ad libitum and were reared on continuous incandescent lighting. From Day 1 to 14 all birds were fed a diet containing corn, soybean meal, and meat and bone meal consisting of 3140 kcal ME/kg, 21.5% CP, 0.93% TSAA, and 1.22%total Lys. From Day 14 to 28 all birds were fed a similarly composed diet consisting of 3160 kcal ME/kg, 19%CP, 0.91% TSAA, and 1.08%Lys. Corn, soybean meal, meat and bone meal, and rice bran were analyzed for CP and amino acid content prior to diet formulation to assure accurate amino acid content. Dietary treatments were also analyzed for amino acids and Cl? Crude protein was calculated as nitrogen (N) X 6.25, amino acid concentrations determined following acid hydrolysis, B p concentration following alkaline hydrolysis, and Met and C y s following performic acid oxidation [q.True digestibility coefficients obtained from published tables [2] were applied to the analyzed amino acid levels in each ingredient to formulate diets on a true digestible amino acid basis. The Illinois Digestible Ideal Amino Acid profile was applied in diet formulation to ensure IDAA adequacy [l]. Ten dietary treatments were replicated five times (600 birddtreatment) in a randomized complete block design. Diet compositions for the finisher (Day 28 to 42) and withdrawal (Day 42 to 52) time periods are presented in Tables 1 and 2, respectively. Finisher diets were formulated to contain 3245 kcal ME kg-', with the digestible Lys calculated to be 0.94%
Downloaded from http://japr.oxfordjournals.org/ at D H Hill Library - Acquis S on March 11, 2015
(0.29%/1000 kcal kg-'). Withdrawal diets also contained 3245 kcal ME kgl, but digestible Lys content was lowered t o 0.84% (0.259%/1000kcal kg-l). The positive control finisher diet contained 19%CP, while the positive control withdrawal diet contained 18% CP.All other diets had CP levels reduced from these initial levels. In addition to meeting the estimated digestible amino acid requirement, all diets were formulated to meet a digestible Cys ratio [l].Treatment 1 was formulated to reflect typical diets utilized in industry, while Treatments 2,3, and 4 were reduced in CP by 2,4, and 6%, respectively. Treatments 5 6 , and 7 were similar to Treatments 2,3, and 4 except that 1% Glu was added as a dispensable amino acid nitrogen source. Treatments 8,9, and 10 were similar to Treatments 5,6, and 7 except that IDAA were supplemented according to an ideal amino acid pattern. All amino acids were added at the expense of corn. Pen BW were obtained on Days 28 and 52 to determine BW gain and feed conversion for the interim time period. Mortality was monitored throughout the experiment. On Day 52, nine birds/pen that were close to the pen average and had no visible signs of abnormalities were randomly chosen for processing. Feed was withdrawn for 12 hr prior to the birds being processed at a pilot processing laboratory. Buds were weighed at the poultry farm on Day 53, transported in coops (less than 1 km) to the processing plant, stunned with an electric knife, bled for 90 sec via severing of the jugular vein, scalded for 2 min, and defeathered in a rotary picker. Eviscera and abdominal fat were removed manually. The abdominal fat was weighed and birds were placed in an ice bath for 12 hr. Carcass parameters measured were live weight, chill weight, Pectoralis major and minor weq$t, thigh meat weight (skinned and deboned), drumstick meat weight (skinned and deboned), and wing weight. Data were analyzed using GeneraI Linear Models of SAS [8], using the pen as the experimental unit for all analysis. All percentage data were subjected to square root transformation prior to analysis. This transformation did not alter statistical interpretation; therefore data are presented as actual percentages. Statements of statistical si@icance are based on P 4.05.
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Supplementation of IDAA to the diets RESULTS AND DISCUSSIONalready containing Glu and reduced in CP by four or six percentage units improved BW gain, but failed to improve gains to the level achieved by birds fed the positive control diet. Supplementation of IDAA alleviated the reduction in feed intake due to Glu supplementation in the diet reduced in CP by six percentage units. The reduced feed conversion noted in diets reduced in CP by four percentage units (Treatments 3 and 6) was improved by IDAA + Glu supplementation (Treatment 9) to a level similar to that of birds fed the positive control diet. Even though daily BW gain and feed conversion improved in birds fed the treatment reduced in CP by six percentage units with IDAA + Glu supplementation compared to birds fed the unsupplemented or Glu-supplemented treatments (Treatments4 and 7, respectively), their performance was not equivalent to that of birds fed the positive control diet. Several studies indicate that birds do not perform as well on low-CP, amino acid-supplemented diets as on higher CP diets [9, 10, 11, 21,221; while other studies suggest that similar performance can be achieved [5, 15, 16, 23, 24, 25, 261. A limitation of this experiment was that IDAA were not tested in the absence of Glu so that IDAA supplementation could be evaluated independently. Dietary treatment had no effect on chick livability. The effects of dietary treatments on processing live weight reflect the results obtained on BW. Percentage chilled carcass weight was reduced due to a reduction in dietary CP by four or six percentage units when no amino acids were supplemented. Supplementation of Glu to the reduced CP treatments did not affect carcass yield. Supplementation of IDAA + Glu to the low-CP treatments, either with or without Glu, improved carcass yield to a level similar to that of birds fed the positive control diet. Percentage abdominal fat was unaffected when dietary CP levels were reduced by two percentage units, regardless of amino acid supplementation (Treatments 2, 5, and 8). This might be expectedbecause dietary amino acid levels were near recommended levels [2]. Further reductions in CP, without supplemental Glu or IDAA + Glu (lkeatments 3 and 4), resulted in increased abdominal fat. Supplementation of Glu to the diets reduced in CP by
Downloaded from http://japr.oxfordjournals.org/ at D H Hill Library - Acquis S on March 11, 2015
Analysis of the mixed diets yielded results in close agreement to the calculated composition (Tables 1 and 2). Performance and processing results of individual treatments are presented in Table 3. Initial BW at Day 28 did not differ due to dietary treatment. Reduction of CP by two percentage units without Glu or IDAA + Glu supplementation (Treatment 2) had no impact on daily BW gain or feed conversion compared to birds fed the positive control diet. However, further reductions in CP (Treatments3 and 4) caused a reduction in BW gain and feed conversion. Reduced CP diets without amino acid supplementationhad little effect on feed intake, although birds fed Treatment 4 exhibited lower feed intake than birds fed Treatments 1,2, or 3. It was not surprisiig that buds fed the treatment reduced in CP by two percentage units had BW similar to birds fed the high protein treatment, since this level of CP reduction results in amino acid levels being relatively close to current recommendations [2] (Tables 1 and 2). That small reductions in dietary CP have little effect on performance has been shown by others [9,10, 111. As dietary levels of CP are further reduced, other IDAA may become limiting and result in reduced performance [9,10,12]. Addition of 1% Glu to the low CP treatments numerically reduced daily BW gains compared to buds fed the unsupplemented diets, possibly due to minor reductions in feed intake. Feed intake was reduced, however, in birds fed the lowest CP treatment with Glu supplementation (Treatment 7). Although Glu is an excellent source of nonspecific N [13], and IDAA are poor sources of nonspecific N [141, the response of broilers to diets containing supplemental Glu varies. Supplementation of Glu to reduced-CP diets has yielded improvements in gain [15] and feed conversion [15, 16, 1 7 . In contrast, Leclercq et al. [18] and Deschepper and de Groote [5] have reported little effect of Glu supplementation on chick performance. The impact of supplemental Glu on feed intake is also unclear. Leclercq et al. [18] showed no effect of Glu on feed consumption, while negative effects of Glu on feed intake have been reported by others [5, 191. Ando et al. [20]noted negative effects of Glu on feed intake, but only when Glu supplementationwas 6% of the diet.
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CONCLUSIONS AND APPLICATIONS 1. Feeding reduced CP diets without amino acid supplementation severely reduced broiler performance and carcass meat yield. 2. Supplementation of 1% Glu exerted no positive effects on bird performance or carcass characteristics and appeared to reduce feed intake, resulting in reduced weight gains. 3. Supplementation of indispensable amino acids according to an ideal amino acid pattern improved broiler performance and carcass meat yield compared to birds fed unsupplemented or Glu-supplemented diets, but failed to completely alleviate some of tht: depressed performance and carcass parameters at the lowest level of dietary CP.
REFERENCES AND NOTES 1. Baker, D.H., 1994. Ideal amino acid profile for maximal protein accretion and minimal nitrogen excretion in m n e a n d poultry. Pages 134-139 in: Proc. Cornel1 Nutr. Conf., Rochester, NY. 2. National Research Council, 1994. Nutrient Reuirements of Poult 9th Rev. Edition. Natl. Acad. $ r e s , Washington, D?? 3. Waldroup, P.W., RJ.Mitchell, J.R Payne, and KR Haze%1976.Performance of chicks fed diets formu-
I
lated to minimize excess levels of essential amino acids. Poultry Sci. 55:243-253. 4. Baker, D.H. and RA. Easter, 1976. Soy prot8:in as a source of amino acids for nonruminant animals.
Pages %9-976 in: World Soybean Research. L.E. Hill, ed. Interstate Printers and Publishers, Dandle, IL.
5. Deschepper, K. and G. de Groote, 1995. Effecl of dietary protein, essential and nonessential amino acids on the performance and carcass compositian of male broiler chickens. Br. Poultry Sci. W229-245.
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six percentage units, supplementation of IDAA + Glu improved the yield of I! majclr, but failed to improve it to the level achieved by birds fed the positive control diet. Suppkmentation of IDAA + Glu to the diet reduced in CP by six percentage units improved the yield of R minor to a level equivalent to birth fed the positive control. Except for the yield of Rmajor of birds fed Treatment 10, supplementation of IDAA + Glu to all the reduct:d CP diets resulted in R major and R mimr yields similar to those of birds fed the positive control diet. Research indicates that dietary CP level has no impact on breast meat yield when crystalline amino acids are supplemented to the low-CP diet [19, 24, 251. [n addition, Summers et ai. [28] and Leclercq er al. [18] reported that total carcass protein content was equivalent between birds fcd high-CP or low-CP, amino acid-supplemented diets. In contrast, Fancher and Jensen [9] and Moran et al. [12] reported that broilers fed low-CP, amino acid-supplemented diets hiid reduced breast meat yields. Yields of deboned thigh meat, deboncd drumstick meat, and whole wings were unaffected by dietary treatment. Similar results have been reported by Kidd et ai. [24], while Moran et al. [12] noted slight differences in thigh yields due to dietary protein level.
four and six percentage units had no effect on percentage abdominal fat. Supplementation of IDAA + Glu to birds fed the diets reduced in CP by six percentage units resulted in abdominal fat levels similar to those of birds fed the positive control. It has been shown that Glu may [9, 10, 19, 271 or may not [15]affect body fat, depending upon the type of diet (51 or broiler genetics used [18]. Increased abdominal fat in broilers fed low-CP, amino acid-supplemented diets has been reported [lo, 12, 21, 241. Inconsistency in amount of body fat may be attributable to the dietary Thr level as recent research suggests that adequate levels of dietary Thr may minimize carcass fatness [23]. Lowering dietary CP by two percentage units (Treatments 2, 5, and 8) did not affect R major or R minor yields. Further reductions in CP (Treatments 3 and 4) reduced R major and f? minor yields. Supplementation of Glu had no effect on R major or R minor yields. This is in agreement with past research [5,15, 18,191 demonstratingno effect of dispensable amino acids on carcass protein deposition. Supplementation of IDAA + Glu to the diet reduced in CP by four percentage units produced only numerical improvements in Rmajor and Rminor yields, each of which were similar to birds fed the positive control diet. In the treatment reduced in CP by
Research Report KERR and KIDD 6. Kerr, BJ., 1995. Nutritional Strategies for Waste Reduction-Management:Nitrogen. Pages 47-68 in: New Horizons in Animal Nutrition and Health (November), Raleigh, NC. 7. Association of OMclal Analytical Chemists, 1984. Official Methods of Analysis. 14th Edition. Assn. Offic. Anal. Chemists, Washington, DC. 8. SASInstitute, 1985. SAWSTATGuide for Personal Computers. Version 6 Edition. SAS Institute, Inc., Cary, NC.
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18. Leclercq, B., A.M. Chagneau, T. Cochard, and J. Khoury, 1994. Comparative responses of genetically lean and fat chickens to me, arginine, and non-essential amino acid sup ly. ?Growth and body composition. Br. Poultry Sci. &:687496.
19. Huyghebaert, G. and M. Pack, 1996. Effects of dietary protein content, addition of nonessential amino acids, and dietary methionine to cysteine balance on responses to dietary sulphur-containing amino acids in broilers. Br. Poultry Sci. 37623-639. 20. Ando, M., H. Hayakawe, and S. HUlkuro, 1989. Effects of dietary arginine, glutamic acid, chlorine, and magnesium on the me requirement for starting chicks. Japan. Poultry Sci. %&l2-308.
21. Skinner, J.T., A L In16 and P.W. Waldroup, 1991. Effects of dietary amino acid levels on performance and carcass com osition of broilers 42 to 49 days of age. Poultry s i . 70:1223-1230.
11. Holsheimer, J.P. and W.M.M.A. Janssen, 1991. Limiting amino acids in low rotein maize-soyabean meal diets fed to broiler chicks from 3 to 7 weeks of age. Br. Poultry Sci. 32151-158.
22. Fancher, B.I. and LS. Jensen, 1989. Dietary protein level and essential amino acid content: Influence upon female broiler rformance during the grower period. Poultry Sci. 68:&908.
12. MOT ET., Jr., RD. Busbong, and S.F. Bilglli, 1992. Reducing dietary crude protein for broilers while satistjmg amino acid requirements by leastcost formulation: Live performance, litter composition, and yield of fast-food carcass cuts at 6 weeks. Poultry Sci. 71:1687-1694,
23. Kidd, M.T. and B.J. Kerr, 1997. Threonine responses in commercial broilers at 30 to 42 days. J. Appl. Poultry Res. 6362-367.
13. Featherston, W.R, 1976. Adequacy of glutamic acid $thesis by the chick for maximal growth. Poultry Sci. 5 24794480.
14. Allen, N.K. and D.H. Baker, 1974. Quantitative evaluation of nonspecific nitrogen sources for the growing chick. Poultry Sci. 53:258-264.
15. Moran, ET., Jr. and H.L Stilborn, 1996.Effect of glutamicacid on broilers given submarginal crude protein wth adequate essential amino acids using feeds high and low in potassium.Poultry Sci. 75120-129. 16.Han, Y.,H. Sudd, C.M. Parsons,and D.H. Baker, 1992. Amino acid fortificationof a low-protein corn and soybean meal diet for chicks. Poultry Sci. 71:1168-1178. 17. Parr,J.F. and J.D. Summers,1991.The effect of minimizing amino acid excesses in broiler diets. Poultry Sci. 70:1540-1549.
24. Kidd, M.T., BJ. Kerr, J.D. Firman, and S.D. B o k g , 1996. Growth and carcass characteristics of broilers fed low- rotein, threonine-supplementeddiets. J. Appl. Poultry l e s . 5:180-190. 25. Holsheimer, J.P., P.F.G. Vereuken, and J.B. Schuttc, 1994. Response of broiler chicks to threoninesup lemented diets to 4 weeks of age. Br. Poultry Sci. 35:&1-562. 26. Stilborn, H.L and P.W. Waldroup, 1989. Utilization of low- rotein grower diets for broiler chickens. Poultry Sci. &(Suppl):142 (Abs). 27. Edmonds, M.S., C.M. Parsons,and D.H. Baker, 1985. Limiting amino acids in low- rotein corn-soybean meal diets fed to growing chicks. Foultry Sci. 64:15191526. 28. Sumnets, J.D., D. Sprall, and J.L Atkinson, 1992. Broiler weight gain and carcass composition when fed diets vaIying in amino acid balance, dietary energy, and protein level. Poultry Sci. 71:26>273.
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10. Fancber, B.I. and LS.Jensen, 1989. Male broiler performance during the starting and growing periods as affected by dieta protein, essential amino acids, and potassium levels. ;4bultry Sci. 68:1385-1395.
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