title: Comparison of Cobb and Ross strains in embryo physiology and chick juvenile growth.
abstract: Broiler performance is known to be related to embryonic developmental parameters. However, strain or genotype differences with regard to embryo physiological parameters and juvenile growth have received little attention. A total of 1,200 hatching eggs produced by Cobb and Ross broiler breeders of the same age were studied. At setting for incubation and between 66 and 130 h of incubation, egg resonant frequency (RF) was measured as an indicator of embryonic development. Also, eggs were weighed before setting and at d 18. From d 10 to 18 of incubation, remaining albumen was weighed. During the last days of incubation, hatching events such as internal pipping (IP), external pipping, and hatch were monitored every 2 h. Hatched chicks were recorded and weighed. At IP stage, gas partial pressures in the egg air chamber were measured. Hatched chicks were reared for 7 d and weighed. Results indicate that RF of Ross eggs were lower than those of Cobb eggs (P < 0.01) and starting time point of RF decrease occurred earlier in Cobb eggs than in Ross eggs. Relative egg weight loss up to 18 d of incubation was lower in Cobb than in Ross (P < 0.05). At IP, partial pressure of CO(2) was higher in Cobb than in Ross (P < 0.05) with shorter incubation duration in Cobb. Between 6 and 60 h posthatch, heat production was higher in Cobb than in Ross (P < 0.05). At 7 d posthatch, Cobb chicks were heavier than Ross chicks (P < 0.05). It is concluded that Cobb and Ross embryos-chicks have different growth trajectories leading in different patterns of growth resulting from differences in physiological parameters.
authors.affiliation: Laboratory of Poultry Sciences, Faculty of Sciences, University of Lome, Lome, Togo. jak_tona@yahoo.com
authors.forename: K
authors.initials: K
authors.lastname: Tona
authors.forename: O M
authors.initials: OM
authors.lastname: Onagbesan
authors.forename: B
authors.initials: B
authors.lastname: Kamers
authors.forename: N
authors.initials: N
authors.lastname: Everaert
authors.forename: V
authors.initials: V
authors.lastname: Bruggeman
authors.forename: E
authors.initials: E
authors.lastname: Decuypere
mesh_terms: D000818:Animals; D002642:Chick Embryo / Q000502:physiology*; D002645:Chickens / Q000145:classification* / Q000254:growth & development* / Q000378:metabolism; D005260:Female; D010047:Ovalbumin / Q000378:metabolism; D017550:Spectroscopy, Fourier Transform Infrared; D013816:Thermodynamics; D013997:Time Factors
chemical_list: D010047:Ovalbumin