The Effect of Genotype and Age of Layer Breeders on Egg Quality Traits

Abstract

The external and internal qualities of 120 eggs (60:60) from Isa Brown (IB) and Bovan Nera (BN) layer breeders were evaluated at 15^th and 30^th week of their production. The genotypes differed significantly (P<0.09) m external egg quality traits except egg weight and egg length. IB recorded higher values in egg width, eggshell weight, eggshell thickness, shape index and shell ratio than BN, while the reverse trend was for egg length. This implies that IB genotype produced eggs with thicker shells than BN, which invariably will lead to a reduction in the rate of cracks and leakages both on the farm and in the hatchery thereby enhancing better hatchability. The age effect was significant (P<0.05) for all the external egg quality traits. The analysis showed that eggs produced at 30^th week were better in terms of external quality traits with the exception of egg shape index. There was positive and significant (P <0.05) interaction effect between genotype and age on eggshell width and shell ratio but not for other traits. As regards internal egg quality traits, the genotypes differed significantly (P<0.05) in all the traits except yolk width, yolk height and albumen weight. IB recorded higher (P<0.05) values in yolk weight, albumen width and yolk ratio than BN, while the latter recorded higher values in albumen height, albumen ratio and haugh unit (HU) than the former The effect of age on internal traits was positive and significant (P<0.05) with the exception f yolk width, albumen width, yolk ratio and albumen ratio. The result showed that the 30^th week analyses recorded higher (P<0.05) values in these traits than 15^th week. This implies that the quality of breeding eggs improves with the advancing age of the birds. Breed x age interactions were significant for yolk weight and albumen width but not found for other traits. IB genotype was considered the best for external egg quality traits and produced thicker eggshell. However, BN genotype produced superior egg quality than lB having recorded higher values (P< 0.05) in HU, which is a determinant of egg quality