Abstract
ABSTRACT This study was performed to determine the effect of shell colour in eggs acquired from Ross-308 broiler breeders on the interior and exterior quality of the egg, the antibody content of the egg yolk, and growth performance. The shell colours of a total of 1350 eggs were classified, using a colorimeter, into three groups: dark (E67). The difference between groups with respect to egg weight, shape index, shell weight, and Haugh unit value was significant. Egg yolk antibody content [...]
Highlights
Eggshell colour is determined at the end of the ovarian channel, in the uterus
The eggshell colour has an effect on yolk antibody content and on the hatchability, but it has no influence on hatchability of fertile eggs, Haugh unit and growth performance
The highest egg weight, shape index, and shell weight were achieved in the light shell colour group and the highest Haugh unit was achieved in the medium shell colour group
Summary
From the moment the eggshell starts to form, the epithelial cells at the surface of the shell gland (uterus) start synthesizing colour pigments (Butcher and Miles, 1995). The pigments that create the shell colour are called biliverdin-IX, zinc chelate, and protoporphyrin-IX. In eggs with blue or green shells, biliverdin and biliverdin zinc chelates are more prominent, while in brown-shelled eggs, the amount of protoporphyrin is higher (Zhao et al, 2006). While the biliverdin pigment has an antioxidant effect, protoporphyrin increases the resistance of the eggshell against breaking (Liu and Cheng, 2010; Ishikawa et al, 2010; Soler et al, 2005). A study performed on blue tit (Cyanistes caeruleus) eggs reported that, according to the structural function hypothesis, the protoporphyrins responsible for the reddish dots on the eggshell are stored in the shell areas where calcium accumulation is lower (Garcia-Navas et al, 2011)
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