Changes in yolk absorption, embryo development patterns and chick quality in small and large eggs obtained from Broiler Breeder Flocks at Different Ages

Abstract

The aim of the present study was to determine the effects of broiler breeder age and egg weight on yolk absorption, embryo development and chick quality in broilers. A total of 3000 hatching eggs were obtained from two different Ross 308 broiler breeder flocks at 36 and 52 weeks of ages. The eggs were classified into two weight categories as small (S: 58-63 g) and large (L: 64-69 g) eggs. To determine the yolk absorption and embryo development during incubation period, yolk absorption, embryo body weight, yolk free body weight and length, shank length were measured on days 14 and 18 of incubation. At hatch, chicks were sampled for determination of chick body weight and length, residual yolk weight and, yolk-free body weight, body and shank length. Yolk absortion and embryo development during incubation period were affected by both breeder age and egg weight. On day 18 of incubation, a higher yolk absorption and relative yolk absorption were observed in embryos from 52 weeks of age flock (9.2g and 43.0%, respectively) compared to other ones from 36 weeks of age (7.8 g and 39.2%, respectively, P<0.01). A lower relative yolk absorption with a value of 39.3% was observed for embryos obtained from large eggs (P<0.01). The embryo body weight and length were found to be higher for embryos obtained from large eggs from 52 weeks of age flock (32.5 g and 17.3 cm, respectively, P<0.01). At hatch, a lower chick body weight with a shorter body length were observed for chicks from 36 weeks of age flock (43.0 g and 20.2 cm, respectively) compared to the chicks obtained from 52 weeks of age (45.1 g and 20.7 cm, respectively, P<0.01). Also, a higher yolk absorption with a heavier chick body weight and length were found for chicks obtained from large eggs compared to small eggs (P<0.01). In conclusion, yolk absorption and embryo development during incubation and subsequently chick quality at hatch were affected by both breeder age and egg weight in broilers.