Prenatal and post-hatch assessment of two strains of broiler chickens reared under high natural ambient temperatures

Résumé

Pre-natal (PN) and post-hatch (PH) assessments were carried out on two broiler chicken strains to examine possible origin of strain differences and response to heat stress. One hundred and forty fertile eggs incubated for 18 days as PN and 192 day-old broiler chicks as PH; were evenly divided between two strains (Arbor Acres [AA] and Marshal [MS]). For the PN assessment (day 18, 19 and 21 of incubation), embryos were dissected and organs weighed. Liver glycogen and moisture content of the carcass and residual yolk sac were also determined. Post hatch, average body weight (ABW), average daily feed intake (ADFI) and feed conversion ratio (FCR) were measured under high natural ambient temperatures. At d 18 of incubation, proportional breast weight and yolk moisture was higher in AA than MS (P < 0.05), with the same trend observed at d 21 for yolk weight (%). Breast, gizzard, heart and liver weights were observed to increase linearly, in proportion to weight of embryo (P <0.001), between d 18 and 21 on incubation, while the inverse was observed for yolk weight (%). Post-hatch, ADFI and FCR at the end of the starter phase were lower in MS compared with AA (P < 0.05). However, at the end of the finisher phase, only ADFI was significantly influenced by strain of broiler (AA < MS; P < 0.05). Serum electrolytes and carcass characteristics did not differ between strains (P > 0.05). Phenotype differences in were manifested prior to hatch, with Marshall exhibiting advantage to Arbor Acres under high ambient temperatures.