Effects of Levels of L-Leucine Supplementation with Sub-optimal Protein in the Diet of Grower-finisher Broiler Chickens on Carcass Composition and Sensory Characteristics

  • Erwan, E. (Institute of Tropical Agriculture, Universiti Putra Malaysia) ;
  • Alimon, A.R. (Institute of Tropical Agriculture, Universiti Putra Malaysia) ;
  • Sazili, A.Q. (Faculty of Agriculture, Universiti Putra Malaysia) ;
  • Yaakub, H. (Faculty of Agriculture, Universiti Putra Malaysia) ;
  • Karim, R. (Department of Food technology, Universiti Putra Malaysia)
  • Received : 2009.05.19
  • Accepted : 2009.11.24
  • Published : 2011.05.01


An experiment involving 180 straight run one-day-Cobb broilers was conducted to evaluate the effect of supplementation of L-leucine with different levels of crude protein (CP) on carcass composition and sensory characteristics of broiler grower-finisher chickens. Six experimental diets comprising two levels of crude protein (CP) i.e., 20 and 20% with three levels of L-leucine i.e. 0, 0.5 and 0.67%, were offered to birds from 21-42 d of age. The birds were randomly divided into 36 experimental pens, 5 chickens in each pen, and there were 6 replicates under each diet. L-leucine supplementation did not affect the bone and lean, whereas fat was decreased (p<0.05) when L-leucine was added at 0.5%. Similarly, there were no significant differences (p>0.05) in the lean, fat and bone among chickens fed two levels of CP. No significant differences between dietary treatments were observed on any sensory characteristics affected by dietary L-leucine and CP. From this study, it is obvious that supplementation of up to 0.5% L-leucine reduced fat. However, other characteristics were not affected by supplementation of L-leucine. Similarly, reduction of body composition and sensory characteristics were not apparent on a diet low in CP.


L-leucine;Crude Protein;Broiler;Carcass Composition and Sensory Characteristics


  1. Association of Official Analytic Chemist. 1980. Official Methods of Analysis. 13th ed. Washington, DC.
  2. Aust, B., L. P. Oddo, F. E. Wild, O. H. Mills and J. S. Deupree. 1987. The descriptive analysis of skin care products by trained panel of judges. J. Soc. Cosmet. Chem. 38:443-449.
  3. Blanchard, P. J., M. Ellis, C. C. Warkup, B. Hardy, J. P. Chadwick and G. A. Deans. 1999. The influence of rate of lean and subcutaneous fat tissue development on pork eating quality. Anim. Sci. 68:477-485.
  4. Bou, R., F. Guardiola, A. Grau, S. Grimpa, A. Manich, A. Barroeta and R. Codony. 2001. Influence of dietary fat source, alpha-tocopherol, and ascorbic acid supplementation of sensory quality of dark chicken meat. Poult. Sci. 80:800-807.
  5. Larmond, E. 1994. Is sensory evaluation a science? Cereal Foods World, 39 (11):804-808.
  6. Busye, J., E. Decupere, L. Berghman, E. R. Kuhn and F. Vandesande. 1992. The effect of dietary protein content on episodic growth hormone secretion and on heat production of male broilers. Br. Poult. Sci. 33:1101-1109.
  7. Castell, A. G., R. L. Cliplef, L. M. Paste-Flynn and G. Butler. 1994. Performance, carcass, and pork characteristics of castrates and gilts self-fed diets differing in protein content and lysine:energy ratio. Can. J. Anim. Sci. 74:519-528.
  8. Cisneros, F., M. Ellis, D. H. Baker, R. A. Easter and F. K. McKeith. 1996. The influence of short term feeding of amino acid-deficient diets and high dietary leucine levels on the intramuscular fat content of pig muscle. Anim. Sci. 63:517-522.
  9. Committee on Medical Aspects of Food Policy. 1984. Diet and Cardiovasculer Disease. Report on Health and Social Subjects no 28. London: HM Stationary Office
  10. Donato, J., G. P. Rogerio, F. C. Vinicius, S. O. P. Ivanir and T. Julio. 2006. Effects of leucine supplementation on the body composition and protein status of rats submitted to food restriction. J. Nutr. 22:520-527.
  11. Elvery, R. L. 1983. Nutritional influences on carcass composition in the broiler chicken. PhD Thesis, University of Nottingham.
  12. Erwan, E., A. R. Alimon, A. Q. Sazili, H. Yaakub and R. Karim. 2009. Effects of varying levels of leucine and metabolizable energy in broiler finishing diet on chicken meat sensory characteristics and carcass composition. Pak. J. Nutr. 8:792-796.
  13. Farmer, L. J. 1999. Poultry meat flavour (Ed. R. I. Richardson and G. C. Mead). Poult. Meat Sci. pp. 127-158 (Walingford, CABI)
  14. Fujimora, S., F. Sakai and M. Kadowaki. 2001. Effect of restricted feeding before marketing on taste active components of broiler chickens. Anim. Sci. J. 72:223-229.
  15. Fujimora, S. and M. Kadowaki. 2006. Improvement of meat taste by dietary components. Bull. Facul. Agri. Niigata Univ., 58(2):151-153.
  16. Halton, T. L. and F. B. Hu. 2004. The effects of high protein diets on thermogenesis, satiety and weight loss: a critical review. J Am. Coll. Nutr. 23:373-385.
  17. Kristensen, L., M. Therkhildsen, B. Rus, M. T. Sorensen, N. Oksbjerg, P. P. Purslow and P. Ertbjerg. 2002. Dietary-nduced changes of mucle growth rate in pigs: effects on in vivo and postmorem muscle proteolysis and meat quality. J. Anim. Sci. 80:2862-2871.
  18. Layman, D. K., R. A. Boileau, D. J. Erickson, J. E. Painter, H. Shiue and C. Sather. 2003. A reduced ratio of dietary carbohydrate to protein improves body composition and blood lipid profiles during weight loss in adult women. J Nutr. 133:411-417.
  19. Layman, D. K., H. Shiue, C. Sather, D. J. Erickson and J. Baum. 2003. Increased dietary protein modifies glucose and insulin homeostasis in adult women during weight loss. J. Nutr. 133:405-410.
  20. Layman, D. K. 2003. The role of leucine in weight loss diets and glucose homeostasis. J. Nutr. 133:261-267.
  21. Mourier, A., A. X. Bigard, E. Kerviler, B. Roger, H. Legrand and C. Y. Guezenec. 1997. Combined effects of caloric restriction and branched chain amino acids supplementation on body composition and exercise performance in elite wrestler. Int. J. Sports Med. 18:47-55.
  22. National Research Council. 1994. Nutrient requirements of poultry. 9th edition (Revised). National Academy Press, Washington, DC
  23. SAS Institute. 1997. SAS/STAT User's Guide. SAS Institute, Inc, NC.
  24. Si, J., C. A. Fritts, D. J. Burnham and P. W. Waldroup. 2001. Relationship of dietary lysine levl to the concentration of all essential amino acids in broiler diets. Poult. Sci. 80:1472-1479.
  25. Smith, T. K. and R. E. Austic. 1978. The branched-chain amino acids antagonism in chicks. J. Nutr. 108:1180-1191.
  26. Steel, R. G. D. and J. H. Torrie. 1980. Principle and procedures of statistics. 2nd ed. McGraw-Hill Book Co., Inc, New York.
  27. Sterling, K. G., D. V. Vedenov, G. M. Pesti and R. I. Bakalli. 2005. Economically optimal crude protein and lysine levels for starting broiler chicks. Poult. Sci. 84:29-36.
  28. Summers, J. D. and S. Leeson. 1984. Nutrition Repmts International 29, 759167.
  29. Waldroup, P. W., Q. Jiang and C. A. Fritts. 2005. Effects of supplementing broiler diets low in crude protein with essential and nonessential amino acids. Int. J. Poult. Sci. 4:425-431.
  30. Westerterp-Plantenga, M. S., M. P. Lejeune, I. Nijs, M. Ooijen and E. M. Kovacs. 2004. High protein intake sustain weight maintenance after body weight loss in humans. Int. J. Obes. Relat. Metab. Disord. 281:57-64.
  31. Zemel, M. B. 2004. Role of calcium and dairy products in energy partitioning and weight management. Am. J. Clin. Nutr. 79:907S-12.