Impact of Star Crack Eggshell Type and Layer Breeder Age on Eggshell Traits, Embryonic Mortality, Hatchability and Chick Quality.

Abstract

Hatching eggs from Hy-Line W-36 strain were obtained from two layer breeder flocks differed in age (46 and 60 weeks). Eggs were randomly taken to evaluate impact of star cracks eggshell compared with normal eggs and layer breeder age on eggshell traits, embryonic mortality, hatchability and chick quality. Egg weight loss in star-cracked eggs was significantly higher than in normal eggs (P < 0.0001), the results indicated that egg weight loss increased with advancing breeder age. Hatchability percentage of chicks hatched from star-cracked eggs had lower in comparison with chicks from normal eggs. Percentage of hatchability decreases with advancing of breeder age for normal eggs (91.8 and 81.3 % at 46 and 60 wks of age, respectively), but this percentage remains almost constant with advancing of breeder age from star-cracked eggs (53.7 and 53.8 %, respectively). There were no significant differences among hatching egg type in terms of chick weight and percentage. The embryonic mortality had differed with different breeder's age. Highly increase in overall mean of embryonic mortality was observed in star crack eggs obtained from the two flocks. Chick length and shank length of chicks hatched from star-cracked eggs was significantly lower than those of chicks from normal eggs. Tona score as a quality indicator was significantly higher in chicks hatched from normal eggs (99.60 %) than those from star-cracked eggs (91.10 %). Blood biochemical parameters were not significantly differed in hatched chicks, except the plasma level of AST was significantly higher in hatched chicks from star crack eggs. Conversely, Cholesterol level was significantly higher in hatched chicks from normal eggs. Finally, This study showed that practically we can benefit from star-cracks eggs, because there is no significant difference between star-cracks and normal eggs for most eggshell characterstics, absolute & relative chick weight, and slightly difference for chick quality.