Digestible tryptophan:digestible lysine ratio in diets for laying hens from 24 to 40 weeks of age

Abstract

-The objective of this study was to determine the ideal digestible tryptophan:digestible lysine ratio in diets for laying hens from 24 to 40 weeks of age. Two hundred and forty Hy-Line W-36 laying hens at 24 weeks of age were distributed in a completely randomized design, with five treatments, eight replicates and six birds per experimental unit. The digestible tryptophan levels in the experimental diets were 1.57; 1.68; 1.79; 1.90 and 2.01 g/kg, providing ratios of digestible tryptophan:digestible lysine of 0.215; 0.230; 0.245; 0.260 and 0.275. The increase in the levels of digestible tryptophan in the diet linearly improved the feed intake, digestible tryptophan intake, digestible lysine intake, egg production, egg mass, feed conversion per egg mass and utilization efficiency of digestible lysine for eggs mass. There were quadratic effects from the digestible tryptophan levels on egg weight. For the efficiency of utilization of digestible lysine for egg mass, there was better adjustment of the data to the LRP model. The level of digestible tryptophan in the diet from which the plateau occurred was 0.184%. This level corresponded to the intake of 142 mg/bird/day of digestible tryptophan and digestible tryptophan:digestible lysine ratio of 0.252. The ideal digestible tryptophan:digestible lysine ratio recommended in diets for laying hens from 24 to 40 weeks of age is 0.252 (25.2%).

Standardized ileal digestible lysine requirement of white commercial layers in peak egg production

“…Basal diet was formulated based on corn and soybean meal to contain 149.58 g CP/kg diet and 2,900 kcal AMEn/kg diet). Ideal digestible ratios of Met + Cys, Thr, Trp, Val, Arg, Ile and Phe + Tyr relative to SID Lys were 103,81,28,96,103,80, and 121%, which corresponded to 3.0 perceptual point above the ratios recommended by Brumano et al (2010), Rocha et al (2013a), Calderano et al (2012), Rostagno et al (2011), Bregendahl et al (2008, Rocha et al (2013b) and Rostagno et al (2011), respectively. Throughout the study, hens were provided mash feed and water ad libitum.…”

“…This increase in egg weight could be related to the higher crystalline amino acid concentration in diets with higher SID Lys content, since essential amino acid supply was concomitantly increased with SID Lys. Once added to diets, essential amino acids like lysine, methionine and tryptophan lead to an increase in egg weight by improving yolk weight and albumen weight (TRINDADE NETO et al, 2011;BRUMANO et al, 2010;CALDERANO et al, 2012).…”

Amino acid requirements for laying hens: a comprehensive review

“…(2019a) 41-60 Hy-Line W36 1.2 vs. 2.0 12.46 85.1 vs. 97.2 Digestible Bregendahl et al. (2008) 28-34 Hy-Line W36 0.9 vs. 1.7 12.51 61.6 vs. 87.9 Calderano et al. (2012) 24-40 Hy-Line W36 1.6 vs. 1.9 12.56 74.9 vs. 78.1 Cardoso et al.…”

“…(2019a) 41-60 Hy-Line W36 Exponential curve 155 54 178 210 226 Means 138.8 166 184 Digestible tryptophan recommendations (mg/bird/day) Weight gain FCR Egg production Egg weight Egg mass Bregendahl et al. (2008) 28-34 Hy-Line W36 Broken line 1 123 49 145 95 119 120 Calderano et al. (2012) 24-40 Hy-Line W36 LRP 145 50 142 144 Cardoso et al.…”

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

“…Methionine + cysteine, tryptophan, isoleucine and valine-to lysine ratios were met in 103% of those recommended by BRUMANO et al (2010), CALDERANO et al (2012), MELLO et al (2012) and ALMEIDA (2014) respectively. Ratios of the other essential amino acids with lysine in digestible basis were supplied, at least, 3% above the recommended by ROSTAGNO et al (2011).…”