Effect of egg turning angle and frequency during incubation on hatchability and incidence of unhatched broiler embryos with head in the small end of the egg

The effect of turning angle (from vertical) and the interaction with turning frequency during incubation on fertile hatchability, embryonic mortality, and the incidence of embryos with head in the small end of the egg (malpositioned) was studied in 2 experiments comprising 2 trials each to determine if a turning angle of less than 45 degrees could be successful. Hatching eggs from commercial broiler breeder flocks from 55 to 61 wk of age were utilized, and turning was for 18 d. Eggs were subjected to turning angles of 35,40, or 45 degrees, with a turning frequency of 24 times daily (24x) in Experiment 1. Turning angle had no effect on fertile hatchability. However, the incidence of separately enumerated, malpositioned embryos was increased by the 35 degrees angle, compared with both the 40 and 45 degrees angles in Experiment 1. Eggs were subjected to turning angles (from vertical) of 35 degrees, with a turning frequency of either 24x or 96x daily, or 45 degrees, with 24x turning in the 2 trials of Experiment 2. Turning angle and frequency had no effect on fertile hatchability or embryonic mortality, but the incidence of separately enumerated, malpositioned embryos was increased by the 35 degrees angle with 24x turning, compared with the 35 degrees angle with 96x turning, and the 45 degrees angle, with 24x turning, in Experiment 2. These data demonstrated that the incidence of malpositioned embryos was increased by a reduced turning angle, but that this effect was ameliorated by a concomitant increase in turning frequency.