Associations among fluctuating asymmetry, duration of tonic immobility, heterophil-to-lymphocyte ratio, and one-legged standing, crooked toes, or footpad dermatitis in chickens.

The purpose of this study was to analyze the associations among fluctuating asymmetry, duration of tonic immobility, heterophil-to-lymphocyte ratio, and one-legged standing, crooked toes, or footpad dermatitis in chickens. In experiment 1, cocks (n = 96; 36 wk old) from 11 Spanish breeds and a White Leghorn population that showed one-legged or normal standing were used. There were no significant differences for the relative fluctuating asymmetry, the duration of tonic immobility, and the heterophil-to-lymphocyte ratio between both groups of cocks, with mean values of one-legged standing birds being similar to those of normal birds. Thus, this pain-related behavior is not associated with some measures of well-being, fear, and stress. In experiment 2, cocks (n = 106; 36 wk old) from 9 Spanish breeds and the White Leghorn population that showed crooked or normal toes were used. Group effect was not significant for the relative fluctuating asymmetry and duration of tonic immobility. Heterophil-to-lymphocyte ratio and heterophil number were significantly greater (P < 0.001) in cocks with crooked toes and smaller in cocks with normal toes, with the opposite being true for lymphocyte number. Thus, this leg problem is associated with the stressfulness of birds and does not contribute to their well-being or fear levels. In experiment 3, cocks (n = 68; 36 wk old) from 5 Spanish breeds with or without footpad dermatitis were used. Group effect was significant for the relative asymmetry of toe length (P < 0.05), the relative asymmetry of cocks with footpad dermatitis being larger. Group x breed interaction was significant for the relative asymmetry of wattle length (P < 0.001), with the difference between cocks with footpad dermatitis and normal cocks being significant in one breed. In this breed (Red-Barred Vasca), fluctuating asymmetry of wattle length was significantly greater in cocks with footpad dermatitis, suggesting that this leg problem negatively affects the well-being of cocks.