Effect of rearing system and genotype of laying hens on the breaking strength of tibia and femur

The aim of this study was to determine the effect of the rearing system and the genotype of laying hens on the breaking strength of the tibia and femur. The experiment was conducted in a 2x2 factorial design with two laying hen genotypes (commercial hybrid Isa Brown and New Hampshire dual-purpose breed) and two rearing systems (floor and organic). At the end of the one-year production cycle, six birds per group (24 hens in total) were randomly selected and slaughtered. To examine the quality of the bones, the femur and tibia were removed from each slaughtered laying hen. The breaking strength was measured by a three-point bending test with the IPNIS device. The results show that the rearing system had no significant effect on the breaking strength of the femur and tibia. On the other hand, genotype had a significant effect on femur and tibia breaking strength, such that the New Hampshire hens had better bone quality than Isa Brown hens. Importantly, there was a significant interaction between rearing system and genotype on tibia breaking strength - in the floor rearing system, the New Hampshire genotype had significantly higher breaking strength than the Isa Brown genotype, while the difference that occurred in the organic system between the genotypes studied was not statistically confirmed.