Effect of Dry-Bulb Temperature, Relative Humidity, and Eggshell Conductance During Days 17 to 21 of Incubation on Egg Weight Loss and Chick Weight

Abstract

Broiler hatching eggs of similar weight were incubated at 37.2 C dry-bulb (DB) temperature and a relative humidity (RH) of 59%. On Day 17 of incubation, the eggs were randomly divided into three groups. The eggs in Group 1 served as the control, the eggs in Group 2 were washed in sodium hypochlorite to disrupt the cuticle, and the eggs in Group 3 were partially dipped in a colloid solution to seal the pores in the pointed region of the eggshell. These treatments altered eggshell conductance.Eggs from all three groups were randomly placed in incubators operating at a DB temperature of 36.7, 37.2, or 37.8 C and at a 59% RH (Experiment 1), or at 51%, 59%, or 67% RH, and at a DB temperature of 37.2 C (Experiment 2). Individual egg weights were recorded on Day 17 (before and after shell treatment), Day 18, Day 19, and at external pipping. Chick weight at hatch, eggshell weight, and time of hatch were also recorded.A DB temperature of 37.8 C resulted in the least weight loss from Day 17 to Day 18 of incubation; a DB temperature of 36.7 C resulted in the least weight loss from Day 18 to Day 19 of incubation. Chick weight at hatch or the time of hatch was not affected by the DB temperature.An incubation RH of 67% resulted in the least weight loss from Day 17 of incubation to external pipping. Chick weight at hatch was not affected by the RH. However, the 67% RH resulted in a significantly longer incubation period. Colloid-treated eggs lost significantly less weight from Day 17 to external pipping than untreated eggs. Chick weight at hatch was unaffected by shell treatment; however, in Experiment 1, the colloid-treated eggs took longer to hatch.