The prevalence of feather pecking and development in commercial flocks of laying hens

Feather pecking and cannibalism remain serious problems when laying hens are intensely farmed, but there is not much data on the true prevalence of feather pecking under commercial conditions. A recent epidemiological survey estimated it to be 37.5%. To verify this value we collected data on the occurrence of feather pecking by means of direct observations. Twenty-five rearing flocks on commercial poultry farms were included in the study. Observations were made in weeks 5, 14, 20, 32 and 50. Additionally plumage condition was evaluated and mortality and egg production were recorded. The observations revealed that 40.0% of all flocks had developed considerable frequencies of feather pecking (>30 feather pecking interactions per 30 individuals per 30 min) by week 5 and by week 14 this had risen to 77.3%. The frequency of feather pecking interactions increased significantly between weeks 5 and 14, then there was a significant decrease at week 20 and the level remained the same in week 32. Feather pecking became more damaging with increased frequency and with increasing age of the birds. Each week the relative amount of severe feather pecking was positively correlated to the overall frequency of feather pecking in a flock and the regression coefficient for these two measurements increased steadily from weeks 5 to 32. Very little damage to the plumage was recorded before week 20, but thereafter damage increased significantly in weeks 32 and 50. Feather pecking did not influence mortality, but egg production was negatively affected in week 32. We conclude that more attention should be paid to the development of feather pecking during the rearing of laying hen chicks. Its consequences are not immediately evident, but frequencies of feather pecking remain high as the birds get older, with damage to the plumage increasing and egg production may be reduced. Therefore, all known risk factors such as a lack of access to elevated perches, high density or bad air quality should be controlled in order to prevent development of feather pecking during the rearing of laying hen chicks. (C) 2001 Elsevier Science B.V. All rights reserved.