Effect of flock age, egg size, and incubator type on embryo development and hatchability in the Indian River Broiler breeders in South Africa

This study investigated the effects of flock age, egg size, and incubator type on embryo development and hatchability traits in the Indian River broiler breed in South Africa. A total of 4752 hatchable eggs from the breeder flocks at 25, 40, and 55 weeks of age were incubated in Linco and Buckeye incubators. Before incubation, eggs were graded into small (49 g), medium (50-59 g), and large (60-69 g) size groups. The general linear model procedure in Minitab 17 was used to analyse data and the means were separated using Fisher’s LSD test (p<0.05). The breeder flocks at 40 weeks of age had higher (p<0.05) hatchability of total eggs set (91.06%), hatchability of fertile eggs set (92.52%), and first-grade chicks (90.93%) followed by 55 week flocks (72.69, 77.37, and 71.18%, respectively) and 25 week flocks (56.39, 64.07, and 55.61%, respectively). The higher proportion (p<0.05) of cull chicks was observed in flocks at 25 (0.78%) and 55 weeks of age (1.52%) compared to 40 weeks of age (0.13%). Flocks at 55 weeks yielded heavier (p<0.05) chicks (44.14g) at hatching. The highest (p<0.05) fertility (98.52%) and lowest total embryo mortality (7.41%) were observed in flocks with 40 weeks of age. Small-sized eggs had the highest (p<0.05) fertility (94.21%) compared to medium-sized eggs (92.80%). Large-sized eggs hatched heavier (p<0.05) chicks (44.21g) compared to medium (39.69g) and small-sized (33.86g) eggs, whereas the other hatchability traits were similar (p>0.05). Incubator type had no significant effect on the incubation and hatchability traits. In conclusion, flock age and egg size were the main determinants of Indian River broiler breed incubation and hatchability traits and should be considered when incubating eggs.