The behaviour of broiler chickens and its modification by lameness

The behaviour of six replicates of broilers obtained from commercial farms, fed ad-libitum and housed on 23-h light:l-h dark schedule at 20 Ix was obs erved using scan sampling. Comparisons were made between sound birds and th ose of varying degrees of lameness between 39 and 49 days of age. Sound bro ilers averaged 76% of their time lying and this increased significantly to 86% in lame birds (gait score 3). Lying also increased with age. Although s ound broilers spent only a minor part of the day on their feet, they spent significantly more time standing idle (78), standing preening (3.5%) and st anding eating (4.7%) than lame birds. Walking declined with age, but occupi ed an average 3.3% of the time of a slaughter-weight broiler. Again, lamene ss significantly reduced this to a minimal 1.5% in the worst affected birds . Sound birds predominantly chose the usual standing posture for eating, wh ereas, lame birds lay down to eat for almost half their feeding time. Detai led observations using video records revealed that lameness altered the fee ding strategy of broilers. Whereas sound birds fed over 50 times in 24 h, t he number of visits to the feeder was reduced with increasing lameness to a n average of around 30 in the lamest broilers. However, meal duration was a djusted to give no overall differences in time spent feeding per day. Time spent drinking was also the same for all birds, averaging 3% of the day. Th e alterations of the time budget, in particular the reductions in activitie s performed whilst standing, and the different feeding strategies adopted, are consistent with lameness imposing a cost on the affected broilers to th e detriment of their welfare. (C) 2000 Elsevier Science B.V. All rights res erved.