1Department of Animal Sciences, Faculty of Agriculture,Islamic Azad University of Saveh, Iran
2Department of Animal Sciences, Faculty of Agriculture,Islamic Azad University of Varamin and Pishva, Iran
Receive Date: 12 August 2010,
Revise Date: 16 October 2010,
Accept Date: 26 October 2010
This experiment was conducted to determine the effect of using L-threonine and reducing dietary levels of crude protein (CP) on egg production criteria in layers. Three hundred of Hy-Line W36 laying hens were used in this experiment. This experiment consisted of three experimental treatments with five replications in each. Experimental treatments included 3 diets with different levels of CP which were 15, 16 and 17% with 0.1, 0.05 and 0.02% L-threonine supplementation, respectively. Experimental period lasted for 5 weeks. In this experiment quantitative factors such as egg mass, egg weight, egg production percentage, feed conversion ratio (FCR), body weight and feed intake were measured. Measured data were analyzed by completely randomized design (CRD). Results indicated that reducing dietary levels of CP to 15% and using L-threonine supplementation had no significant effect (P>0.05) on laying criteria. According to economic analysis, the treatment containing 15% CP and 0.1% L-threonine was the most beneficial treatment.
Bunchasak C. and Silapasom T. .(2005). Effects of Adding Methionine in Low-Protein Diet on Production Performance, Reproductive Organs and Chemical Liver Composition of Laying Hens under Tropical Conditions. Int. j. poult. sci. 4, 301-308. Ferguson N.S., Gates R.S., Taraba J.L., Cantor A.H., Pescatore A.J., Straw M.L., Ford M.J. and Burnham D.J. (1998). The effect of dietary protein and phosphorus on ammonia concentration and litter composition in broilers. Poult. Sci.77, 1085-1093. Harms R.H. and Russell G.B. (1993). Optimizing egg mass with amino acid supplementation of a low-protein diet. Poult. Sci. 72, 1892-1896a Poultry revision 7. Hsu J.C., Lim C.Y. and Chiou P.W. (1998). Effects of ambient temperature and methionine supplementation of low-protein diet on the performance of laying hens. Anim. Feed Sci. technol.74, 289-299. Hussein A.S. (2000). The use of step-down and modified constant protein feeding system in development of pullets reared in hot climates. Anim. Feed. Sci. Technol. 85, 171-181. Keshavarz K. and Jackson M.E. (1992). Performance of growing pullets and laying hens fed low-protein, amino acid supplemented diets. Poult. Sci. 71, 905-918. Kidd M.T. and Kerr B.J. (1996). L-threonine for Poultry: A Review. J. Appl. Poult. Sci. 5, 358-367. Kidd M.T., Kerr B.J. and Anthony N.B. (1997). Dietary Interactions Between Lysine and Threonine in Broilers. Poult. Sci. 76, 608-614. Leeson S. and Caston L.J. (1996). Response of immature Leghorn pullets to low-protein amino acid fortified diets at 18 or 30ºC. J. Appl. Poult. Res. 5, 155-160. Leeson S., Summers J.D. and Caston L. (1998). Performance of white and brown egg pullets fed varying levels of diet protein with contend sulfur amino acids, lysine and tryptophan. J. Appl. Poult. Res. 7, 287-301. Waldroup P.W. (2000). Feeding programs for broilers: the challenge of low protein diets. Proc. MD Nutr. Conf. Feed Manufact. 47, 119-134. Waldroup P.W., Kersey J.H. and Kidd M.T. (2002). Dietary interactions between Threonine and crude protein in diets for growing Tom turkeys 8 to 12 weeks of age. Int. j. poult. sci. 1(4), 74-77.