The Effect of Humidity and Broiler Strain on Egg Weight Losses During Incubation

Abstract

Two independent trials were conducted to determine the influence of relative humidity (RH) on broiler egg weight losses during incubation. In each trial, eight stacks of incubation trays containing 150 broiler hatching eggs per stack were separated into four pairs of stacks. Each pair contained two stacks of equivalent weight. One stack from each pair was incubated at a constant 55% RH and the other stack was incubated in an RH profile that gradually increased from 52% RH early in incubation to 67% RH during late incubation. Stack weights were determined again on 1.5, 7.5, 15.5 and 18.0 days of incubation. Data were analyzed by paired t tests. In both trials the RH profile resulted in lower egg weights (P<.05) by 1.5 days and higher egg weights (P<.05) by 7.5 days of incubation than the 55% RH treatment. No differences in egg weights were found after 7.5 days of incubation. No difference was found between the two RH treatments in either fertility or hatchability.In another experiment, which involved two trials, hatching eggs from two commercial broiler strains were incubated at a constant 55% RH. In one trial, at 18.0 days of incubation, there was a significant difference in egg weight (P<.05) between the two strains. No difference was found between the two strains in either fertility or hatchability.Relatively minor, short-term RH changes influenced egg weight losses during early incubation, but similar changes had no significant effect on weight losses during late incubation.