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

Fariborz Khajali,M Faraji,Saeid Karimi Dehkordi

doi:10.3844/ajavsp.2007.89.92

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.

Highlights

Current standard practice to feed Hy-line W 36 is allocation of a series of diets termed starter, grower and developer, during 0-6, 6-9 and 9-17 wk of age, respectively[7]
Leeson and summers[10] reported that pullets given the step-up protein regime had significantly lower body weight at 20 wk of age than those on step-down protein system
Cantor and Johnson[4] reported that increasing protein levels sequence (13-16-19%) during the rearing period decreased pullet body weight up to 20 wk of age and reduced egg production, whereas feeding a constant protein sequence (16-16-16%) had no effect on 20-wk body weight or egg production, when both compared to the conventional decreasing protein level sequence

Summary

Introduction

Current standard practice to feed Hy-line W 36 is allocation of a series of diets termed starter, grower and developer, during 0-6, 6-9 and 9-17 wk of age, respectively[7]. Keshavarz[8] observed lower body weight at 20wk and decreased performance during the early phase of egg production cycle when pullets were given low-protein diets during the rearing period. The present study used a low-protein diet with similar total sulfur amino acids: lysine ratio as the control and effects of feeding these diets on pullet development and subsequent laying performance were studied.

Results

Conclusion