Effects of Reduced- Protein Diets at Constant Total Sulfur Amino Acids: Lysine Ratio on Pullet Development and Subsequent Laying Hen Performance

Abstract

The effect of using a low protein regime in pullet development and subsequent layer performance was studied. The experiment consisted of two periods of rearing and laying. Two hundred and sixty Hy-line W36 chicks were used. In the rearing period, dietary protein level and ME content series of the control group used during starter (18-42), grower (43-63) and developer (64-119d) phases were 20, 2930, 18, 2930, and 16, 3025, respectively. Dietary protein sequence of the low protein group was 18.5, 16.5, and 14.6% during the respective periods. In the laying period lasted from week18 to week32 of age, CP content of the control and reduced-protein diets were 17.8 and 16.3%, respectively. Reduced-protein diets were kept isoenergetic with their corresponding controls in each period and phase and they balanced to keep the same total sulfur amino acid to lysine ratio as well. Results indicated that birds on reduced-protein diet during starter phase of the rearing period consumed less feed (p = 0.003) and as a result they had significantly (p = 0.012) better feed conversion ratio (FCR) compared to the control. However, dietary protein regime had no significant effect on weight gain, feed intake and FCR during grower and developer phases. In the laying period, there was no significant difference in terms of layer performance and egg quality criteria. In conclusion, reduced-CP diets can be satisfactory used for rearing pullets and laying hens up to 32 weeks of age.