Effect of Egg Weight and Genotype on Egg Quality in Brown and White-Egg Layer Pure Lines Housed in Enriched Cage System

Abstract

This study investigated the effect of egg weight and genotype on egg quality traits in brown-egg (Line-54, RIR 1, RIR 2, COL, BAR 1, and BAR 2) and white-egg (D-229, Brown, Blue, Black, and Maroon) layer pure lines reared in enriched cage system. 20 eggs from each pure line were collected in one day at 33 weeks of hen age and classified into four different weight groups: small (S: ≤ 52 g), medium (M: 53-63 g), large (L: 63-72 g), and extra-large (XL: ≥ 73 g) according to Turkish Food Codex Communiqué on Eggs and Egg Products before the analysis of physical egg quality traits. It was identified that brown-egg pure lines differed regarding the shell-breaking strength, shell thickness, albumen index, and Haugh unit, all greatest in RIR 2 eggs and yolk color score, highest in BAR 2 eggs (P<0.05; P<0.01). White-egg pure lines only varied regarding yolk color score, highest in Blue pure line eggs (P<0.05), and the genotype effect on meat-blood inclusions in the yolk approached a significant level (P=0.065), the highest number of eggs with inclusions in D229 pure lines. For egg weight, while only the Haugh unit (P<0.05) varied among egg weight groups in brown-egg pure lines; highest in M and L eggs, the shape index, shell breaking strength, shell thickness, and yolk index differed greatly among the egg weight groups in white-egg pure lines (P<0.05; P<0.01). The egg weight did not significantly affect meat and blood inclusion in the yolk and albumen in both pure line groups (P>0.05). In conclusion, while brown-egg pure lines differed in several egg quality traits, the white-egg pure lines varied in only the yolk color score. The egg weight and genotype effect on egg quality traits need to be refined. The egg quality traits of the white-egg pure lines seemed to be significantly affected by the egg weight. Egg weight seemed to affect egg quality majorly in white-egg pure lines.