Associations between weather conditions and individual range use by commercial and heritage chickens.

Ranging area use by domestic poultry is not always optimal and differences in it exist on the levels of breed, flock and individual bird. Outdoor shelters are usually not protective for all weather parameters and may not fulfil a protective role to all birds within the flock all time, if individuals are sensitive to different weather conditions. The aim of this study was to investigate associations between different weather parameters and the use of the range by individual Green-legged Partridge and Sasso C44 chickens. In August 2018, 60 birds per genetic strain were housed in groups of 10 from wks 5 to 10, under conditions exceeding minimal EU requirements of organic meat chicken production. Birds in each pen had access to an outdoor range that was video-recorded during the experiment to obtain frequencies of individual birds' use of the ranges. Weather data were collected each minute throughout the whole experiment by an automatic weather station. In each pen, birds tagged individually with a laminated color tag, had access to an outdoor range that was video-recorded during the experiment. Frequencies of individual birds' use of the ranges were manually obtained from the recordings. Univariate and multivariate linear regression models were used to investigate the associations between the variables. The results showed significant associations between weather parameters and range use for one third of Green-legged Partridge and Sasso chickens (n = 21 in both breeds). Between breeds, range use associations with different weather parameters were identified. Negative associations with relative humidity occurred most frequently in Green-legged Partridges (n = 8; R from 0.1 to 0.17), while positive associations with atmospheric pressure (n = 7; R from 0.09 to 0.17) were most common in Sasso chickens. Further investigations into the reasons behind individual sensitivity of meat-purpose chickens to specific weather conditions would increase the understanding of their preferences and needs, which over time will improve animal welfare.