Impact of Strain, Egg Type, Breeder Age and Their Interactions on Hatching Traits and Chick Quality.

Abstract

Eight hundred hatching eggs from two Hy-Line chicken strains (400 Brown and 400 W-36) were acquired from two layer breeder ages (46 and 60 weeks). In each age there are four egg types (normal, large, rough and shape abnormality), each type containing fifty hatching eggs from each age either for Brown or W-36 chicken strains. Thus, this experiment was a 2×2×4 factorial design. There were no significant differences between strains for relative egg weight loss. Egg weight loss (%) increases with the breeder age. Relative egg weight loss was significantly higher in rough and abnormal eggs compared to their counterparts. Rough eggs type of brown strain at different breeder age had the lowest fertility and hatchability percentages compared to other egg types. Abnormal shape egg type had the lowest value of shape index. Brown chickens produced eggs had significantly higher relative eggshell weight compared to the white one. Shell percentage significantly decreases with advancing of hen's age. White eggs significantly recorded higher total pores per egg (7583) compared to the brown one (7249). Total pores significantly increases with breeder age. Large egg type was significantly higher in total pores compared to other egg types. Eggs with rough shell type had the highest embryonic mortality percentage in early stage (0-7 d of incubation) for each brown and W-36 strains at different ages, followed by eggs with shape abnormality compared to other egg types. Large egg type was significantly higher in hatched chick weight (46.85 g), then shape abnormality (41.12 g). There were no significant differences between strains for Tona score as indication of chick quality. Tona score decreased as the layer breeder age progressed. Rough egg type had the lowest value of Tona score (78.25 %); whereas, no significant difference was observed between other studied egg types (normal; 99.80, large; 95.65, and abnormal; 95.25 %). Tona score was significantly affected by all potential interactions, that means the expression of this trait was different based on strain, layer breeder age and egg type. It could be concluded that practically we can benefit from large and shape abnormality eggs, because there is no significant difference between them and normal eggs for most eggshell characteristics, chick quality and fertility & hatchability percentages.