Digestible threonine:lysine ratios for light laying hens from 29 to 45 weeks

Abstract

The objective was to determine the nutritional requirement of digestible threonine and the threonine: lysine ratios for light laying hens from 29 to 45 weeks of age. Two hundred Hy-Line-36® hens were distributed in a completely randomized design with five replicates and 10 birds per experimental unit and four treatments (5.50, 5.77, 6.05 and 6.30 g digestible threonine kg-1), establishing threonine: lysine of 69, 73, 76 and 80%. Four production cycles of 28 days each were evaluated: feed intake, feed conversion (kg dz-1), feed conversion (kg kg-1), egg laying percentage, weight and egg mass, percentage of egg components, internal egg quality and shell thickness. No effect of threonine levels was observed on egg production, weight and egg mass, internal egg quality, albumen and yolk percentage, specific gravity, shell thickness, feed intake, feed conversion (kg dz-1) and feed conversion ratio (kg kg-1). The ratio of digestible threonine: lysine to light laying hens in the period from 29 to 45 weeks is 69%, which corresponds to a daily consumption of 520 mg threonine bird-1 day-1.