Effect of breeder age and lighting regimen on growth performance, organ weights, villus development, and bursa of fabricius histological structure in broiler chickens

This study was carried out to investigate the effect of breeder age and lighting regimen on performance, some organ weights, villus development, and bursa of fabricius histological structure in broiler chickens. A total of 384 one-day-old chicks were obtained from two Ross broiler breeder flocks at 32 (young; Y) and 49 (old, O) weeks of age. Chicks from each breeder age were reared under 18 h light : 6 h dark (18 L : 6 D) (control; CL) or 14 L : 4 D : 2 L : 4 D (split darkness, SD). Body weight, feed intake, feed conversion ratio, and mortality were measured weekly during the experiment. At 21 days of age, liver, heart, spleen, and bursa of fabricius weights were recorded, gastrointestinal tract and jejunum lengths were measured, and histomorphometry of villi and bursa of fabricius structure were investigated. Interaction between breeder age and lighting regimen was observed, where Y-CL chicks had the lightest body weight from 7 to 35 days (P < 0.05). Neither breeder age nor lighting regimen influenced feed conversion ratio. SD chicks had longer (P < 0.05) gastrointestinal tract and jejunum, and wider villus in comparison to CL chicks. Lower relative spleen weight was observed in CL chicks compared to SD ones (P < 0.05). It was concluded that split darkness lighting regimen could be used for broiler chickens from young breeders to improve live body weight without affecting feed conversion ratio.