The influence of egg shell crack types on hatchability and chick quality


Abstract: Fertile eggs were obtained from a commercial flock of Ross broiler breeders (51 weeks old) and candled to determine the presence of hairline or star cracks. Eggs (5400 total) were assigned in equal numbers to 3 treatments (hairline-cracked, star-cracked, and normal eggs) and incubated for 21 days. Upon hatching, 10 chicks per treatment were euthanized, and organ weights were measured. Compared with normal eggs, the presence of egg shell cracks (regardless of type) resulted in higher egg weight loss at the time of transfer; a decrease in hatchability, hatch of fertile eggs, chick length, yolk-free body mass (P < 0.01), and percentage of hatchling breast and liver weight (P < 0.05); and an increase in the contamination rate of eggs (P < 0.01). Weight loss in hairline-cracked eggs was significantly higher than in star-cracked eggs (P < 0.001). Percentage hatchability and body weight of chicks hatched from star-cracked eggs was higher than in chicks from hairline-cracked eggs (P < 0.001). Crack type did not have a significant effect on chick length and body weight uniformity; however, the Pasgar score as a quality indicator was higher in chicks hatched from star-cracked eggs than those from hairline-cracked eggs (P < 0.05). There were no significant differences among treatments in terms of heart and small intestine weight. The contamination rate of hairline-cracked eggs was higher than that of star-cracked (P < 0.01). A higher incidence of embryonic mortality was observed during days 1-8 of incubation for shell-cracked eggs (P < 0.001). Total embryonic mortality in hairline-cracked, star-cracked, and normal eggs was 51.1%, 36.6%, and 13.3%, respectively. This study showed that egg shell cracks reduced incubation parameters and chick quality. The negative effects of hairline cracks were more pronounced than those of star cracks.

Keywords: Egg shell, hairline crack, star crack, hatchability, chick quality, embryonic mortality

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