Effects of Housing System and Cold Stress on Heterophil-to-Lymphocyte Ratio, Fluctuating Asymmetry, and Tonic Immobility Duration of Chickens

Abstract

The purpose of this study was to analyze the effect of housing system and cold stress on the heterophil-to-lymphocyte ratio, the fluctuating asymmetry, and the tonic immobility duration of chickens. In experiment 1, hens (n=120; 36 wk old) from 5 Spanish breeds and a White Leghorn population, which had been housed in pens with or without access to an outdoor area from 20 wk of age, were used. The effect of housing system on heterophil-to-lymphocyte ratio varied from breed to breed, differences between housing systems being significant (P<0.05) in 2 breeds. In these breeds (Red-Barred Vasca and Birchen Leonesa), heterophil-to-lymphocyte ratio was significantly greater in hens housed in deep litter. Housing effect was significant for the relative asymmetry of leg length (P<0.01), wattle length (P<0.05), and the combined relative asymmetry (P<0.05), the relative asymmetry of hens housed in deep litter being larger. There was no significant difference for the duration of tonic immobility between hens housed in deep litter or free range. Thus, hens with access to an outdoor area were less stressed than hens without access to an outdoor area, although the fearfulness was similar in both groups of birds. In experiment 2, cocks (n=120; 36 wk old) from 4 Spanish breeds, a synthetic breed, and the White Leghorn population, which had been housed in cages with or without a cold stress (0 to 10 degrees C) from 24 wk of age, were used. Cold x breed interaction was significant for heterophil-to-lymphocyte ratio (P<0.05), differences between cold-stressed and control birds being significant in 2 breeds. In these breeds (Red-Barred Vasca and Buff Prat), heterophil-to-lymphocyte ratio was significantly greater in cold-stressed birds. Cold stress effect was significant for the relative asymmetry of toe length (P<0.001) and the combined relative asymmetry (P<0.05), the relative asymmetry of birds with cold stress being larger than that of control birds. Thus, cold stress seriously negatively affects the welfare of cocks.

The welfare of slow growing broiler genotypes reared in organic system

“…Some study showed that genotypes had considerable variations in terms of TI (Campo et al, 2000). In the present study TI of slow-growing broilers had excessively lower (ranged 57.70 to 93.77 s) with outdoor access than those (ranged 158 to 398 s) of Campo et al (2008), who tested six different Spanish breeds. Likewise, Prieto and Campo (2010) stated that TI found 99 s in White Leghorn reared with standard temperatures.…”

“…Besides, they are subjected to various factors as well as infectious and parasitic diseases, social interactions and unfavourable climatic conditions that may expand both stress and fear reactions and depress wellbeing. As criteria for measuring levels of stress, welfare and fear in chickens is predicted to duration of tonic immobility (TI) and fl uctuating asymmetry (FA) (Campo et al, 2008;Dávila et al, 2011).…”

Effect of Genotype and Husbandry System on Blood Parameters, Oxidative and Native Immune Status: Welfare and Implications on Performance of Organic Laying Hens

“…There is a genetic component to heterophils and lymphocytes responses to stressors [59]. Bayyari et al [60] reported that lymphocyte numbers were lower in a line of turkeys selected for heavier BW than in a line selected for increased egg production.…”

Hen welfare in different housing systems

“…Fear is an adaptive response, but it can also be undesirable if it results in extreme distress or injury or if it is chronic (Jones, 1996). Several studies have been conducted to compare levels of fear in different housing systems as an indicator of hen welfare in those systems (Hansen et al, 1993;Colson et al, 2005;Campo et al, 2008;Graml et al, 2008). However, such studies are very difficult to interpret and extrapolate to commercial housing conditions.…”