We examined the effects of two different methods of castration on the behaviour of lambs of two age groups. Rubber ring castration and combined rubber ring and Burdizzo clamp castration were compared in groups of one-week-old lambs and four- to six-week-old lambs. Behaviour was assessed
by examining time-lapse video recordings made continuously over four days. Postures and behavioural states were instantaneously sampled and the mean daily frequencies of these behaviours calculated. Behaviours were assigned to different groups: standing still, moving, eating, lying, playing
and abnormal postures. The times spent performing each group of behaviours on the days following castration (days 2, 3 and 4) were compared to those on the day preceding castration (day 1). Castration resulted in significant reductions in the times spent performing play behaviour in one-week-old
lambs and lying behaviour in four- to six-week-old lambs. There was also a significant increase in abnormal postures following castration in four- to six-week-old lambs. There were no detectable differences between castration methods. The results show that lambs exhibit changes in behaviour
over the three-day observation period that are suggestive of the presence of prolonged acute pain. These results have important implications regarding the sheep welfare recommendations of the Farm Animal Welfare Council, which propose to extend the maximum legal age for rubber ring castration
from one week to six weeks of age.