Assessment of digestible amino acid requirement in White leghorn Layers based on production performance at low protein levels in diet

Abstract

To understand the optimal requirement of d.lysine and threonine in White Leghorn (WL) layers (25-44 weeks), two independent experiments were executed. For the d. lysine study, birds (N=528) were categorized into eleven dietary groups (11×6×8) and were fed with two different protein levels (13.36 and 15.78%) each containing five concentrations of d. Lys. To optimize d. Thr, layers (N=390) were allotted to thirteen groups (13×5×6) in these diets were formulated by fixing the lysine concentrations at 0.65 and 0.60% with 13.36 and 15.78% protein levels respectively. Threonine was supplemented in both diets at graded levels of lysine. Basal diets with 0.70% lysine and 17% protein; threonine at 66% lysine served as corresponding controls. Egg production response to supplemental d. Lys was quadratic. Net feed efficiency and egg mass indices response were in both linear and quadratic. Supplementation of diets with Thr, the response of egg production was linear whereas, it was both linear and quadratic for economic parameters. In conclusion, supplementation of d. Lys at 0.65 and 0.60%; 69 and 72% d. Thr as % of d. Lys at low and high protein diets is optimal for better egg production with economic efficiency in WL layers in the tropics.