Digestible threonine to lysine ratio in diets for laying hens aged 24-40 weeks

Abstract

-Two-hundred sixteen white laying hens were used to assess the ideal ratio of digestible threonine:lysine in diets for laying hens at 24 to 40 weeks of age. Birds were assigned to a randomized block design, with six treatments, six replicates per treatment and six birds per experimental unit. The cage was used as the blocking criterion. Experimental diets contained different digestible threonine:digestible lysine ratios (65, 70, 75, 80, 85 and 90%) with 142 g/kg of crude protein.Experimental diets were formulated to be isonitrogenous and isocaloric with different contents of L-glutamic acid. Feed intake (g/hen/d), egg production (%), egg weight (g), egg mass (g/hen/d), feed conversion ratio (kg/dozen and kg/kg egg), eggshell weight (g), albumen weight (g), yolk weight (g) and body weight gain (g) were assessed. The maximum egg production was observed at 78% digestible threonine:digestible lysine ratio, while the best values of feed conversion ratio (kg/dozen egg) and feed conversion ratio (kg/kg of egg) were observed at 77.6% and 75%, respectively. Feed intake, egg mass and egg contents (yolk, albumen and eggshell) were not affected by treatments. The estimated digestible threonine:digestible lysine ratio of Hy-Line W36 laying hens at 24 to 40 weeks of age is 78%, corresponding to 5.70 g/kg of dietary digestible threonine.

Digestible threonine-to-lysine ideal ratio for laying hens fed with low-protein diets from 24 to 40 weeks of age

“…Thr-to-Lys ratio of 60%, which corresponds to digestible Thr intake of 434mg bird -1 , maintaining adequate egg quality of white laying hens from 24 to 40 weeks of age. ROCHA et al (2013), as well as observed in this trial, did not observe effects of dietary dig. Thrto-Lys ratios on albumen, yolk and eggshell weight and percentage for white laying hens from 24 to 40 weeks of age.…”

“…Digestible Thr-to-Lys ideal ratio estimated for optimum egg production (80%) in this trial was greater than the one determined by ROCHA et al (2013), who established the dig. Thr-to-Lys ratio of 78% as ideal for Hy-Line W-36 laying hens at the same age.…”

“…Thr-to-Lys ratio of 78% as ideal for Hy-Line W-36 laying hens at the same age. The greater Thr need reported in this trial compared to those observed by ROCHA et al (2013) may be justified by the higher egg production rate observed in this trial (93.78%) compared to the authors (84.42%). The average egg production in this trial was 92.60%, which is approximately 1% inferior to the recommended by the genetic line guideline (HY LINE W36, 2015).…”

“…Thr-to-Lys ideal ratio and Thr requirement for white laying hens with egg mass of 55.50g is respectively 76% and 610mg bird -1 day -1 ; whereas, according to ROCHA et al (2013) such ratio for Hy Line W-36 laying hens from 24 to 40 weeks of age is 77.60%.…”

Exigência nutricional de lisina digestível para galinhas poedeiras leves em produção

“…As relações da metionina + cistina; treonina; triptofano; isoleucina e valina com a lisina ficaram três pontos percentuais acima do estipulado por BRUMANO et al (2010), ROCHA et al (2013a), CALDERANO et al (2012), ROCHA et al (2013b) e BREGENDAHL et al (2008, respectivamente. As relações da arginina; leucina; histidina; fenilalanina e fenilalanina + tirosina com a lisina ficaram no mínimo três pontos percentuais acima do preconizado por ROSTAGNO et al (2011).…”