Welfare impairment of lambs around weaning. Play and other behaviour indicative of affective state

Abstract: The abrupt and early weaning of intensively kept lambs may have serious animal welfare implications, but relatively little is known about this. Weaning includes the breaking of the mother-young bond and abrupt replacement of milk by solid food, often coinciding with changes in the (social) environment. Altogether, these changes are likely to affect lamb welfare significantly. This study aimed to establish how strong and persistent lamb welfare is impaired following abrupt weaning by means of measuring behaviour parameters indicative of affective state. Also, we investigated the existence of a diurnal rhythm in play behaviour, which is considered an important indicator of positive affect and good welfare. Play behaviour was studied in combination with other (potentially) useful welfare parameters, mainly indicative of negative affective state. In order to investigate the effect of weaning on welfare, behaviour was recorded of 15 twin lambs that were weaned in two steps at 50-65 days of age. Firstly, the mother was removed from the home pen and placed within hearing distance of the lambs, and secondly the mother was removed from the barn. Durations of behavioural occurrences were scored for body movement, feeding, ear posture and tail posture and frequencies were recorded for play behaviour, social contact and vocalisations. Moreover, the lambs were weighed every week. Diurnal rhythms in locomotor and social play behaviour of lambs were investigated in 5 pre-weaned twins that were camera recorded for 24h. Statistics focussed on testing for effects of weaning period, sex and an interaction of these two on the different behaviours. There was a significant effect of weaning period (i.e. before weaning, during the time the ewe was moved from the lambs’ pen but still in the same barn, and after removal of the ewe from the barn) on total play (P=0.006), social play (P=0.018) and locomotor play (P=0.019), with a reduction in play during weaning. Social contact with the twin lamb and vocalisations increased in the period during weaning to regain its previous level after weaning (both P<0.001). Increases during weaning lasted respectively 2 and 3-4 days. The duration that the lambs were lying reduced during weaning (P=0.032). The plane ear posture was shown less in the period during weaning than before weaning (P<0.001), whereas raised and asymmetrical ear postures both increased rapidly during weaning. Play behaviour was affected by sex differences, playground size, sex ratio of the playmates, and hour of the day. For example, pre-weaning total play (P=0.004), social play (P=0.013) and locomotor play (P=0.003) occurred especially during the 7th (7:00-8:00), 9th (9:00-10:00) and 19th (19:00-20:00) observation hour. The removal of the mother from the home pen to another pen in the same barn, and concurrent reduction of space and separation of playmates by bars (i.e. during weaning), evoked behavioural changes indicative of negative affect that lasted 2 to 4 days. The removal of the mother from the barn after another 5 days (i.e. after weaning) had minimal effects on behavioural parameters and weight gain. Play behaviour was reduced by weaning, but in a rather subtle way which does not make it a powerful indicator for on farm welfare assessment. Alternative indicators of welfare seem to be vocalisations, social contact with the twin, raised and asymmetrical ear posture and, possibly, the percentage of time lying. Pre-weaning, the lambs appeared to have a diurnal cycle of play, though this probably reflected in part the activities of the caretakers. The present study shows that impaired lamb welfare is likely to follow from the conventional weaning method as indicated by a number of behavioural parameters.