title: Influence of thermal stimulation during the late phase of incubation on hatching results and post-hatch broiler performance under commercial conditions.
abstract: Two experiments, which differed in breeder age, strain and season, were conducted to study the influence of low-intensity, short-duration thermal stimuli during the late phase of incubation on hatchability and performance. The first experiment conducted in April-June used eggs from Cobb × Ross broiler breeders at 35-41 weeks of age and the second experiment performed in February-April used eggs from Hubbard × Cobb broiler breeders at 49-53 weeks of age. Eggs in the test group had the same physical environment as eggs in the control group except that incubation temperature was increased by 1˚C for 2 h/d above the control group from 18 to 20 d of incubation (DI). The results demonstrated that thermal stimulation of 1˚C for 2 h/d above control incubation temperature during 18-21DI did not have any adverse effects on hatch and post-hatch performance of broilers. In both experiments, treatment did not significantly alter the secondary sex ratio in hatched chickens, but hatch residue showed that the proportion of unhatched male embryos was significantly lower in the test groups than in the control groups. In the first experiment, thermal stimulation improved feed conversion by 1.82% compared with the control.
authors.affiliation: a Department of Animal and Veterinary Sciences , Clemson University , Clemson , SC , USA.
authors.forename: A S
authors.initials: AS
authors.lastname: Elmehdawi
authors.affiliation: a Department of Animal and Veterinary Sciences , Clemson University , Clemson , SC , USA.
authors.forename: M A
authors.initials: MA
authors.lastname: Hall
authors.affiliation: a Department of Animal and Veterinary Sciences , Clemson University , Clemson , SC , USA.
authors.forename: P A
authors.initials: PA
authors.lastname: Skewes
authors.affiliation: b Fieldale Farms Corporation , Baldwin , GA , USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Wicker
authors.affiliation: a Department of Animal and Veterinary Sciences , Clemson University , Clemson , SC , USA.
authors.forename: D V
authors.initials: DV
authors.lastname: Maurice
mesh_terms: D000822:Animal Husbandry / Q000379:methods*; D000818:Animals; D002642:Chick Embryo; D002645:Chickens / Q000254:growth & development / Q000502:physiology*; D004734:Energy Metabolism; D005260:Female; D006358:Hot Temperature; D008297:Male; D010063:Ovum / Q000502:physiology*; D011897:Random Allocation; D012098:Reproduction; D012744:Sex Ratio