Effect of flock age, length of egg storage, and frequency of turning during storage on hatchability of broiler hatching eggs.

Broiler hatching eggs from two young (30 and 31 wk) or two old (52 and 53 wk) breeder flocks were stored for 3, 7, or 14 d at 18 C and 75% RH while being turned 0, 4, or 24 times per day in two experiments. Apparent fertility and hatchability of total eggs differed with flock age in both experiments, but the effect was greater in Experiment 1. Hatchability of total and fertile eggs were decreased with flock age in Experiment 1 (31 and 52 wk flocks), but only hatchability of total eggs was decreased in Experiment 2. Hatchability of fertile eggs declined with length of storage period in both experiments with the most obvious effect observed in eggs stored 14 d. There was an increase in percentages of early and late embryonic mortality with length of storage period in both experiments. Hatchability of fertile eggs was increased by turning 4 or 24 times per day during storage in Experiment 1 or by four times per day, with 24 times per day intermediate, in Experiment 2. There were no storage time x turning in storage interactions. A significant interaction of flock age x turning in storage for hatchability of fertile eggs in Experiment 1 suggested that eggs from an older broiler breeder flock that exhibit reduced fertility benefited more from turning during storage than did eggs from a young broiler breeder flock.