Investigation on the Effects of Various Protein Levels with Constant Ratio of Digestible Sulfur Amino Acids and Threonine to Lysine on Performance, Egg Quality and Protein Retention in Two Strains of Laying Hens

Abstract

An experiment was conducted to determine the possibility of using various levels of crude protein (CP) by providing laying hens with constant levels of digestible sulfur amino acid, threonine and lysine to improve performance and egg quality. The experiment was conducted as a completely randomized block design in a factorial arrangement (4×2) with 8 replicates of 10 hens in each. Factors included 4 levels of CP (18.5%, 17.5%, 16.5% and 15.5%) and 2 strains (LSL and Hy-Line W-36) of laying hens. Hens were fed experimental diets from 25 to 33 weeks of age. Production performance was measured for eight weeks and egg quality characteristics were determined at 29 and 33 weeks of age. Protein reduction decreased egg weight, egg mass and hen body weight linearly (P≤0.01). Egg production was not affected by protein reduction but feed efficiency, and average daily feed intake increased significantly (P≤0.01). Lohmann Selected Leghorn laying hens showed significantly higher egg production, egg weight, egg mass, weight gain, feed efficiency and feed intake compared to the W-36 laying hens (P≤0.01). Shell thickness increased linearly as protein levels decreased (P≤0.05). There were significant differences between two strains on the egg quality characteristics (P≤0.01). Significant (P≤0.05) CP × strain interactions were observed for hen weight, albumen height, Haugh units, yolk and shell percentage. Based on the results of this experiment, a reduction in dietary protein level (from 18.5% to 15.5%), without any alteration in digestible TSAA and Thr: Lys ratio, led to inferior egg mass and feed conversion ratio during the peak production period.

Effect of Protein Levels in Diet on Production and Emissions in WLH Layer

“…In contrast to these, Mousavi et al (2013) observed linear increase in egg production (92.32 to 93.63%) with increase in crude protein (15.5 to 17.5%) in diet.…”

Effect of replacing soybean meal (Glycine max) with kidney bean (Phaseolus vulgaris) on egg quality parameter of white Leghorn layers

“…Albumin height and egg weight have a direct and indirect contribution for the HU values, respectively in which the increase in albumin height increase the he HU and the increase in egg weight decrease HU. This is in line with the result demonstrated by Suk and Park (2001) that albumen weight is positively associated with egg weight and that of Mousavi et al (2013) who reported independence of HU and albumen height from dietary CP level. Wu et al (2007) Related HU to nutrients and stated that the HU of hens fed higher nutrient density was significantly lower than that of hens fed lower nutrient densities, probably because of the higher egg weight of hens fed the high nutrient density.…”

Effects of crude protein levels on egg quality traits of brown layers raised in two production systems

“…Regarding the yolk relative weight, our results do not agree with Mousavi et al (2013), who investigated the effects of different levels of crude protein (15.5, 16.5, 17.5, and 18.5%) on the quality of the eggs of Lohmann LSL and Hy-Line W-36 lines between 25 and 33 weeks of age. These authors used diets formulated from the concept 35 weeks and 40 to 45 weeks of age) and reported that the yolk relative weight was higher for the breeding system in conventional cages.…”