The effects of high incubating temperature on the growth of the chick embryo

Abstract

During the second half of incubation, 112 eggs from White Leghorn hens and Leghorn x Australorp cocks were randomly allocated to four equal groups and incubated at 37.6° (control), 40.6°, 41.7° and 42.8°C respectively. On day 17, all eggs were candled, opened and their embryos were weighed. As incubating temperatures increased, embryonic mortality also increased (3.5, 0, 25.0, 50.0 % respectively, P < 0.01) and embryo weight decreased (18.5, 17.3, 13.0 and 11.7 g, P < 0.001). The effects of high temperature on embryonic mortality and growth of the chicken are very similar to those previously reported in sheep. This suggests the use of the avian embryo as a readily managed model in investigating the mechanism of heat action in both species.