Rearing laying hens: Early environmental complexity and genetic strain have life-long effects on keel bone size and fractures

Abstract

Keel bone damage (KBD) is a major welfare concern for laying hens. Environmental complexity during rearing is suggested to promote skeletal development and reduce KB fractures (KBF). We investigated the effect of rearing environment and genetic strain on KB development and health. Three consecutive replicate flocks of brown (B) and white-feathered (W) layer chicks (3000/ flock) were raised in three styles of rearing aviaries of Low, Mid, or High complexity and in conventional cages (Conv). Pullets from flocks 1 and 3 (1080/ flock) were subsequently housed in 24 furnished cages of two sizes (small: 30 vs large: 60 birds) for lay. Samples of pullets and hens were assessed as follows: Dissections at six, 11, and 16 WoA in flocks 1 and 2 for KB size, radiographs at 30, 50, and 70 WoA in flocks 1 and 3, for KBD and dissections at 70 WoA in flock 3 for KBD.Rearing complexity affected KB size of pullets (Conv small, P= 0.049).In conclusion, rearing complexity and strain affected KB size and fracture severity and prevalence. These data confirm that complex rearing aviaries that are known to promote exercise reduce KBF severity and prevalence throughout lay.

Keywords

• Laying hens
• Pullets
• Keel bone fractures
• Aviary housing
• Furnished cages