Effects of moist litter, perches, and droppings pit on fluctuating asymmetry, tonic immobility duration, and heterophil-to-lymphocyte ratio of laying hens.

The purpose of this study was to analyze the effects of moist litter, perches, and droppings pit on the fluctuating asymmetry, the tonic immobility duration, and the heterophil:lymphocyte ratio of laying hens. In experiment 1, hens from 4 Spanish breeds and a White Leghorn population, that had been housed in moist or dry litter pens from 20 wk of age, were used. Treatment effect was significant for the fluctuating asymmetry of toe length (P < 0.05), the fluctuating asymmetry of hens housed in moist litter pens being larger. The duration of tonic immobility was significantly longer (P < 0.01) in hens housed in moist litter pens. Thus, litter moisture is associated with the well-being or fear levels of hens, as indicated by the fluctuating asymmetry and the tonic immobility duration. In experiment 2, hens from the Black Menorca breed, that had been housed in pens with or without perches from 20 wk of age, were used. The fluctuating asymmetry of wattle length and the combined fluctuating asymmetry were significantly greater (P < 0.001) in hens housed in pens without perches. Thus, the presence of perches is associated with the well-being level of birds, as indicated by the fluctuating asymmetry. In experiment 3, hens from 4 Spanish breeds and a White Leghorn population, that had been housed in pens with or without a droppings pit, were used. There was significant difference for the fluctuating asymmetry of leg length (P < 0.001) between hens housed in pens with or without a droppings pit, the fluctuating asymmetry of hens housed in pens without a droppings pit being larger. There were no significant differences for the duration of tonic immobility and the heterophil:lymphocyte ratio between both treatments. Thus, the presence of a droppings pit is associated with the well-being of hens, as indicated by the fluctuating asymmetry, and does not contribute to their fear or stress levels, as indicated by the tonic immobility duration and the heterophil:lymphocyte ratio.