Comparative assessment of general behaviour and fear-related responses in hatchery-hatched and on-farm hatched broiler chickens

摘要

Traditionally, broiler chickens hatch in the hatchery and they are usually not provided with feed and water until placement at the farm. This can have negative effects on their health and welfare. Therefore, alternative systems providing early nutrition, for instance by hatching eggs in a poultry house (on-farm hatching) are increasingly being used in practice. However, information on the behaviour and welfare of on-farm hatched chickens in relation to hatchery-hatched chickens is very limited. This study aims to gain basic knowledge of the behaviour of on-farm hatched chickens (OH) by comparing them to a control group (C) hatched in the hatchery. In addition, fear-related responses were assessed as indicators of chicken welfare. About 13,800 chickens per treatment group were reared in three consecutive batches in eight floor pens under semi-commercial conditions. Direct behavioural observations and three different fear tests, i.e. a novel environment, a human approach and a novel object test, were carried out between two and 36 days of age. Except for 'disturbance behaviour' (i.e. pushing or overrunning another chicken), which was more often performed by the OH chickens (F-1,F-3 = 35.10, P < 0.05), no effect of treatment was found on general behaviour. In contrast, nearly all observed behaviours were affected by the chickens' age (F-4,F-24 = 4.02-41.81, P < 0.05). In the fear tests, most variables, for instance average latency of chickens touching a human and the number of chickens in the vicinity of a novel object, differed between the treatments (P < 0.05) with OH chickens being more fearful and less active. The present results indicate that the hatching system (hatchery-hatching vs. on-farm hatching) seems to have limited effects on broiler chicken activity and general behaviours. In test situations, however, hatchery-hatched chickens showed more active and less fearful responses compared to on-farm hatched chickens. The underlying causes for these differences in response to more challenging situations remain to be investigated further, as these may be related to a higher intrinsic motivation to search for food or more exposure to humans or objects in the hatchery in C chickens as compared to OH chickens, but also to differences in coping style or development of cognitive abilities between the treatment groups.