Behavioural response of grazing lambs to changes associated with feeding and separation from their mothers at weaning.

This study aimed to determine which behaviours were provoked in lambs in response to the separation from their dams or to the changes associated with feeding and separation from adults at weaning. Fourteen lambs were separated from their dams at 24-36 h after birth and artificially reared (AR) in presence of four adult ewes, while another 13 lambs remained with their dams from birth (DR). At 75 days of age on average (day 0) DR lambs were separated from their dams and AR lambs no longer received sheep's milk and were separated from adults. Behaviours were recorded every 10 min (6h per day) from day -3 to day 4. We observed an increase (p<0.05) in pacing behaviour, as well as in the frequency in which lambs were observed vocalizing, walking and staying under shade, and a decrease (p<0.05) in the frequency of grazing in the DR group in comparison to AR at weaning, but there were no differences in body weight gain from day -4 to day 5 after weaning. Additionally, we observed a decrease in the frequency in which lambs were observed standing and grazing (p<0.05), and an increase in vocalizing and staying under shade (p<0.05) in group AR at weaning in comparison to the previous days. Therefore, it was concluded that although some specific behaviours as pacing or vocalizing were clearly related with the separation from the mother at weaning, the change of food and separation from adults must be also considered as an important stressor in grazing lambs at weaning. In addition, the provision of shade when grazing is also important for lambs at the time of weaning.