Research Note: The influence of housing system on digestive system, femur and tibia bone dimensions of laying hens

The aim of the study was to evaluate the relationship between housing systems for laying hens and the morphometry of the digestive tract as well as the dimensions of limb bones. The experimental material consisted of carcasses of Lohmann Brown laying hens after the laying period, which had been kept in three different housing systems: cage (CC), litter (SS), and aviary (SW). From each system, 15 hens aged 85 weeks were collected, and slaughter was carried out in a commercial slaughterhouse in compliance with all procedures. The research hypothesis assumed that different housing systems would affect the dimensions of the digestive tract, tibia and femur bones, as well as the percentage contribution of selected internal organs. The housing system significantly affected the total intestinal length and all its segments, which were statistically shorter in hens kept in the CC system compared with those from SS and SW, except for the caecum (P < 0.05). In the SS system, the diameter of the duodenum, ileum, and rectum was significantly higher (P < 0.05) compared with CC and SW. The rearing system had a significant effect on the percentage of the liver (P = 0.004), heart (P < 0.001), and gizzard (P < 0.001). Birds kept in the SS system had the highest percentage liver, spleen, and heart. Only for the greatest breadth of the proximal end of the femur was a statistically significant lowest value recorded (P = 0.019) in the CC system compared with SS and SW. The conducted study demonstrated that the housing system of laying hens significantly affects the morphometry of the digestive tract, the percentage of selected internal organs, and the dimensions of limb bones. The results confirm that more diversified housing systems (litter and aviary) promote better anatomical development of hens compared with the cage system.