Determination of range enrichment for improved hen welfare on commercial fixed-range free-range layer farms

Abstract

An observational study on range enrichment was conducted on three commercial fixed-range, free-range layer farms comprising four flocks in South Australia (flock sizes ranged from 3000 to 11700 hens). Two strategies were compared; a ‘standard’ Control treatment, typical of the type of range used in the commercial industry and a highly ‘enriched’ treatment. Both treatments were implemented on the same range with no subdivisional fences. The highly enriched side of the range incorporated shade shelters, alongside a continuum of additional enrichment structures (e.g. dust baths, peck objects and hay bales). Range treatments were investigated to determine the effects on motivating hens to use the range more effectively, and their potential to lead to a decrease in abnormal behaviours, such as injurious feather pecking and cannibalism. Additionally, two farms with high levels of tree coverage were also observed. Farms were visited monthly for 6 months. At each visit several measures were recorded live: the numbers of hens out on the range, location of hens on the range and plumage score of birds outdoors and indoors. Enrichment structure utilisation on the range was measured via video recordings and continuous counts of the number of hen visits to enrichment structures within 1 h. It was found that more hens used the ‘enriched’ side of the range, in comparison with the ‘standard’ Control range treatment (P ≤ 0.01). Overhead cover provided by constructed shelters and dust bathing pits were instrumental in enticing birds out onto the range (306 ± 27 s.e.m. and 366 ± 24 s.e.m., average number hen visits). Hay bales were also highly utilised (116 ± 14 s.e.m., average number hen visits), even though the hen numbers attracted to the hay bales were not as high as shelters and dust baths. It was also observed on one property that natural cover provided by trees attracted the greatest number of hens (1652 ± 358 s.e.m., average number of hen visits). Prevailing weather conditions and the age of the flock strongly influenced the number of hens utilising the range outdoors. Furthermore, hens outside on the range had better plumage scores with lower feather loss and decreased areas of bare skin compared with birds scored in the shed.