Effect of frequency of turning from three to eleven days of incubation on hatchability of broiler hatching eggs

Hatching eggs from broiler breeder flocks at 37, 41, 59, and 63 wk of age were stored for 1 or 2 d at 18 C and 75% RH and then turned 24, 48, or 96 times per day from 3 to 11 d of incubation. All eggs were turned 24 times per day from 1 to 2 d and 12 to 18 d of incubation. Fertile hatchability was better at 37 and 41 wk of age than at 59 and 63 wk of age due primarily to increased early dead embryos. Fertile hatchability was increased by turning 96 times per day compared to either 24 or 48 times per day. This improvement was due to a reduction in late embryonic mortality. There was no significant interaction of flock age x turning in storage for fertile hatchability or embryonic mortality.