title: The effect of nonventilation during early incubation on the embryonic development of chicks of two commercial broiler strains differing in ascites susceptibility.
abstract: Despite thorough selection during the last decade, the incidence of ascites is still high in modern broiler strains. Although ascites occurs mostly at the end of the rearing period, there are indications that the etiology of this problem may have started during embryonic development. Recent studies have shown that the post-hatch performance of the broiler chick might be influenced by changing the environmental conditions in the incubator during embryonic development. This study investigated the effect of increasing incubator CO(2) concentration up to 0.7%, by nonventilation during the first 10 d of incubation, on the embryonic development of 2 commercial broiler strains (Cobb and SAS) differing in their susceptibility for ascites syndrome. The Cobb strain is suspected to be less susceptible than the SAS strain. Overall, the chick embryos of the Cobb strain had a faster development than those of the SAS strain as expressed by their higher BW from embryonic day (ED)10 until ED18. Nonventilation stimulated embryonic development resulting in higher embryonic BW, early hatch, and narrower spread of hatch in both strains. In the SAS strain, nonventilation improved hatchability by more than 10%. Gas composition of the air cell in the egg of the nonventilation groups (both Cobb and SAS) had higher partial pressure of CO(2) and lower partial pressure of O(2) from ED11 until ED14 compared with the ventilation groups. During the entire incubation period, partial pressure of CO(2) was higher in eggs of the Cobb strain compared with the SAS strain. Plasma triiodothyronine, thyroxine, and corticosterone levels were different at the end of the incubation period and during hatching due to nonventilation at the beginning of incubation. It is concluded that nonventilation during the first 10 d of incubation had a stimulatory effect on embryonic development of the 2 broiler strains with no effect of heart weights but with effects on hormone levels, air cell pressures, and hatching parameters.
authors.affiliation: Lab of Physiology of Domestic Animals, Katholieke Universiteit Leuven, Kasteelpark Arenberg 30, 3000 Leuven, Belgium. Lieve.desmit@biw.kuleuven.be
authors.forename: L
authors.initials: L
authors.lastname: De Smit
authors.forename: V
authors.initials: V
authors.lastname: Bruggeman
authors.forename: M
authors.initials: M
authors.lastname: Debonne
authors.forename: J K
authors.initials: JK
authors.lastname: Tona
authors.forename: B
authors.initials: B
authors.lastname: Kamers
authors.forename: N
authors.initials: N
authors.lastname: Everaert
authors.forename: A
authors.initials: A
authors.lastname: Witters
authors.forename: O
authors.initials: O
authors.lastname: Onagbesan
authors.forename: L
authors.initials: L
authors.lastname: Arckens
authors.forename: J
authors.initials: J
authors.lastname: De Baerdemaeker
authors.forename: E
authors.initials: E
authors.lastname: Decuypere
mesh_terms: D000818:Animals; D001201:Ascites / Q000209:etiology / Q000517:prevention & control / Q000662:veterinary*; D002245:Carbon Dioxide / Q000032:analysis; D002642:Chick Embryo / Q000254:growth & development* / Q000502:physiology; D002645:Chickens / Q000097:blood / Q000254:growth & development / Q000502:physiology*; D003345:Corticosterone / Q000097:blood; D007185:Incubators; D009038:Motion; D010100:Oxygen / Q000032:analysis; D010313:Partial Pressure; D011201:Poultry Diseases / Q000209:etiology* / Q000517:prevention & control; D013963:Thyroid Hormones / Q000097:blood; D013974:Thyroxine / Q000097:blood; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood; D014691:Ventilation
chemical_list: D013963:Thyroid Hormones; D014284:Triiodothyronine; D002245:Carbon Dioxide; D013974:Thyroxine; D010100:Oxygen; D003345:Corticosterone