Effect of Different Cage Densities and Age on Keel Bone Damage and Some Hormones in Laying Hens

ABSTRACT

This study aimed to determine the effect of three distinct cage densities (750 cm²/hen, 535 cm²/hen, and 375 cm²/hen) on the keel bone damage of brown (Hyline Brown, HB) and white (Isa Tinted, IT) laying hens by x-ray method. Moreover, osteocalcin (OC), calcitonin (CT), and parathormone (PTH) hormones were examined by taking blood from a total of 162 laying hens (54 laying hens from each period) at the 35^th, 51^st and 60^th weeks. The research took place from laying hen ages of 20 to 60 weeks. A total of 396 laying hens (198 HB, 198 IT) were used in the research. Scoring was done at the end of the experiment, using the x-ray images of the chest area of the laying hens at the 35^th, 51^st, and 60^th weeks (162 laying hens). A ‘0’ score was attributed to images with deviation and fracture; while those without them were attributed a score of ‘1’. The hormones examined were not affected by cage density. Only PTH hormone differed according to age (p<0.05) and genotype (IT > HB) (p<0.001). It was determined that keel bone damage (deviation, p=0.009) was greater at low cage density, and age had no effect on damage occurrence. The study showed that the cage density applied in conventional cage systems may affect keel bone damage.

Keywords:
Cage density; Conventional cage; Keel bone damage; Laying hens; Welfare