Influence of supplemental lysine, isoleucine, threonine, tryptophan and total sulfur amino acids on egg weight of Hy-line W-36 hens

Abstract

Four experiments were conducted to determine whether synthetic lysine, isoleucine, threonine, and tryptophan (LITT) or TSAA supplementation to diets formulated based on lysine improved egg weight (EW) and hen performance. In Experiment 1, diets were formulated with three TSAA levels (0.65,0.72, and 0.81%). These diets were fed with and without adding lysine and isoleucine each at 0.055% and threonine and tryptophan each at 0.022%. Treatments were randomly assigned to 960 Hy-Line W-36 hens in eight replicates per treatment (20 birds/replicate). Inclusion of LITT improved (P < 0.05) EW within 2 wk with no TSAA × LITT interaction. Inclusion of LITT also increased average feed consumption (FC) by 1.4 g/d (P < 0.01). However, no effect (P > 0.05) of LITT was observed on egg production (EP), egg specific gravity (SG), or BW. The EW, EP, and FC increased linearly (P < 0.05) as dietary TSAA increased. The TSAA had no effect on SG or BW. In Experiment 2, supplemental LITT were removed to determine how rapidly hens lose the effect of LITT on performance. Within 2 wk, the effect of LITT on EW was lost. Average EW, EP, and FC of hens fed higher TSAA levels remained higher (P < 0.05) than hens fed 0.65% TSAA. In Experiment 3, all hens were fed a diet containing 0.65% TSAA to determine the time it takes to lose the effect of TSAA supplementation. The TSAA supplementation effect on EW, EP, and FC observed in the previous two experiments was lost within 1 wk. In Experiment 4, hens were again fed diets similar to Experiment 2 to confirm the time required for TSAA supplementation to improve EW. Within 1 wk, hens fed 0.72 or 0.81% TSAA improved (P < 0.05) EW over hens fed 0.65% TSAA. It was concluded that hens fed diets formulated based on lysine were deficient in LITT. Hens responded to the inclusion or removal of supplemental LITT and TSAA within 1 to 2 wk.