Effects of Air Humidity During Incubation and Age After Hatch on Heat Tolerance of Neonatal Male and Female Chicks

Abstract

Effects of incubation 45 versus 55% relative humidity (RH) and early versus late hatching time on heat tolerance of neonatal male and female chicks were studied. Chicks were exposed for 48 h to temperatures of 35 (Experiment 1), 37 (Experiment 2), or 39 C (Experiment 3). Chicks that hatched from eggs incubated at 45% RH were lighter at hatch than chicks that hatched from eggs incubated at 55% RH. Chicks that hatched from eggs incubated at 55% RH lost more body weight and water during heat exposure than those that hatched from eggs incubated at 45% RH. Body weight and water loss during heat exposure of chicks that hatched early and late was similar. However, chicks that hatched late maintained their initial heat production and respiratory quotient better during heat exposure than chicks that hatched early. Body weight and water loss of male and female chicks was similar. At 37 and 39 C, heat production of chicks fell to lower values during the 2nd day of exposure compared with the 1st day. It was concluded that chicks that hatched late, i.e., with a short holding period in the hatcher, and coming from eggs incubated at 45% RH had increased heat tolerance in comparison with the other chicks.

Influence of post hatch dietary supplementation of fat on performance, carcass cuts and biochemical profile in Ven Cobb broiler

“…Apart from that fat also influence the immune response of individuals. The respiratory quotient in hatching chicks in the range of 0.72-0.74 [ 10 ], indicating utilization principally of fat.…”

Meeting embryonic requirements of broilers throughout incubation: a review

“…Hatching time was not affected by the percentage of relative humidity during incubation in this study. Hamdy et al (1991) showed that the body weight of chickens was 0.7 g higher when eggs were incubated at a relative humidity of 55% compared to 45%. Excess water is probably incorporated into the tissue of the chicken (Davis et al, 1988), but in studies by Hamdy et al (1991), Swann & Brake (1990b), and Bruzual et al (2000a), this extra water was rapidly lost after hatching.…”

“…Hamdy et al (1991) showed that the body weight of chickens was 0.7 g higher when eggs were incubated at a relative humidity of 55% compared to 45%. Excess water is probably incorporated into the tissue of the chicken (Davis et al, 1988), but in studies by Hamdy et al (1991), Swann & Brake (1990b), and Bruzual et al (2000a), this extra water was rapidly lost after hatching. As a result, no difference in body weight was observed at pull time (Bruzual et al, 2000a), and this suggests that the period and conditions between hatch and arrival at the farm affect hatchling quality more than the relative humidity during incubation.…”

“…Bruzual et al (2000b) suggested that chickens of a young breeder flock incubated at a relative humidity level of 43% were more sensitive to sub-optimal brooding conditions than chickens of a young breeder flock incubated at relative humidities of 53 and 63%, but the reason for this difference was not given. Hamdy et al (1991) showed that chickens that hatched from eggs incubated at 45% relative humidity could better cope with high temperatures during transport than chickens that hatched from eggs incubated at 55% relative humidity. The reason for this difference is unclear, but the chickens in the 45% relative humidity treatment may have produced less heat than the other chickens (Hamdy et al, 1991).…”

“…Hamdy et al (1991) showed that chickens that hatched from eggs incubated at 45% relative humidity could better cope with high temperatures during transport than chickens that hatched from eggs incubated at 55% relative humidity. The reason for this difference is unclear, but the chickens in the 45% relative humidity treatment may have produced less heat than the other chickens (Hamdy et al, 1991).…”