Effect of Various Levels of Protein in Diet Based on Total and Digestible Amino Acids on Performance of Cobb Strain Broilers

Document Type : Research Article


Department of Animal Science, Karai Branch, Islamic Azad University, Karai, Iran


In order to study the effects of various levels of protein in diet based on total and digestible amino acids on performance and carcass traits of broilers, an experiment was conducted as a completely randomized design with 288 broiler chicks from Cobb 500 strain in 6 treatments, each treatment consist of 3 replicates with 16 chicks per replicate. Treatments were the diets as follow: 1) diet formulated based on digestible amino acids which has 1% less crude protein (CP) than Cobb 500 recommendation (2006); 2) diet formulated based on digestible amino acids with CP similar to Cobb 500 recommendation; 3) diet formulated based on digestible amino acids with 1% higher CP than Cobb 500 recommendation; 4) diet formulated with total amino acids with one level lower than suggested protein level in Cobb 500 recommendation; 5) diet formulated with total amino acids with suggested protein level in Cobb 500 recommendation and 6) diet formulated with total amino acids with one level lower than suggested protein level in Cobb 500 recommendation. The metabolizable energy was considered constant and diets were fed to birds during 42 days of experiment. Daily weight gain, feed consumption, feed conversion ratio, breast meat yield and abdominal fat content were measured. At the end of experiment, 4 chickens (2 males and 2 females) from each treatment was randomly selected and killed and their carcasses were analyzed. Results indicated that formulating ration`s protein based on total amino acids for Cobb 500 broilers shows better performances than digestible amino acids.


Ayasan T., Okan F. and Hizli H. (2009). Threonine requirement of broilers from 22 to 42 days. Int. J. Poult. Sci. 8(9), 862-865.
Bartov I. and Plavnik I. (1998). Moderate exec of dietary protein increases breast meat yield of broiler chicks. Poult. Sci. 77, 680-688.
Corzo A., Kidd M.T., Burnham D.J., Miller E.R., Branton S.L. and Gonzalez-Esquerra R. (2005). Dietary amino acid density effects on growth and carcass of broilers differing in strain cross and sex. J. Appl. Poult. Res. 14, 1-9.
Dari R.L., Penz A.M., Kessler A.M. and Jost H.C. (2005). Use of digestible amino acids and the concept of ideal protein in feed formulation for broiler. J. Appl. Poult. Res. 14, 195-203.
Fancher B.I. and Jensen L.S. (1989). Influence of varying dietary protein content while satisfying essential amino acid requirements upon broiler performance from three to six weeks of age. Poult. Sci. 68, 113-123.
Fernandez S.R. and Parsons C.M. (1996). Bioavailability of the digestible lysine and valine in cottonseed and soybean meals. Poult. Sci. 75, 216-223.
Fernandez S.R., Zheang Y. and Parsons C.M. (1995). Dietary formulation with cottonseed meal on a total amino acid in diets for broilers from different strain. 2. fat content. Arch. Geflugelk. 46, 177-188.
Han Y. and Baker D.H. (1993). Effect of sex, heat stress, body weight and genetic strain on the lysine requirement of broiler chicks. Poult. Sci. 72, 701-708.
Hoehler D., Lemme A., Ravindran V., Bryden W.L. and Rostagno H.S. (2005). Feed formulation in broiler chickens based on standardized ileal amino acid digestibility. Pp. 23-24 in Proc. 3rd Mid-Atlantic Nutr. Conf. Timonium, Maryland.
Lemme A. (2003). The “ideal protein concept” in broiler nutrition 2. Experimental data on varying ideal protein levels. Amino NewsTM. 4, 7-14.
Maiorka A., Dahlke F. and Penz A.M. (2005). Diets formulated on total or digestible amino acid basis with different energy levels and physical form on broiler performance. Revista Brasileria de Ciencia. Avicola. 7, 47-50.
NRC. (1994). Nutrient Requirements of Poultry, 9th Rev. Ed. National Academy Press, Washington, DC., USA.
Perttila S., Valaja J., Partanen K., Jalava T. and Venäläinen E. (2002). Apparent ileal digestibility of amino acids in protein feedstuffs and diet formulation based on total versus digestible lysine for poultry. Anim. Feed Sci. Technol. 98, 203-218.
Rosebrough R.W. and McMurtry J.P. (1993). Energy repletion and lipid metabolism during compensatory gain in broiler chickens. Growth Dev. Aging. 57, 73-83.
Sarwar M., Khan M.A. and Iqbal Z. (2002). Status paper on feed resources for livestock in Pakistan. Int. J. Agric. Biol. 4, 186-192.
SAS Institute. (1996). SAS®/STAT Software, Release 6.11. SAS Institute, Inc., Cary, NC. USA.
Thomas D.V., Ravindran V. and Ravindran G. (2008). Nutrient digestibility and energy utilization of diets based on wheat, sorghum or maize by the newly hatched broiler chick. Brazilian Poult. Sci. 49, 429-435.
Waibel P.E., Carlson C.W., Liu J.K., Brannon J.A. and Noll S.L. (1995). Replacing protein in corn-soybean turkey diets with methionine and lysine. Poult. Sci. 74, 1143-1158.
Widyaratne G.P. and Drew M.D. (2011). Effects of protein level and digestibility on the growth and carcass characteristics of broiler chickens. J. Poult. Sci. 90, 595-603.