LAUSR

Abstract Ewes develop a strong selective bond with their offspring, which is set immediately after lambing and maintained until weaning, which in domestic sheep occurs when lambs are 4–5 months old. However, in productive systems lambs are weaned earlier, when they are 2–5 months old. The aim of this experiment was to determine how long the preference for the mother is maintained after abrupt weaning in lambs that have been nursed by their dam for 3 months. Eighty-two single Corriedale lambs stayed with their mother until weaning at 3 months of age, when they were abruptly separated from their mothers and moved to another paddock located 1500 m away, avoiding any mother-young communication. Preference for the mother was tested using a two-choice test between their own and another mother from the same flock, matched for age and physiological status. Lambs were tested in a 10 m × 10 m × 7 m triangular testing enclosure with one ewe placed in each of the two holding pens. A wire mesh plastic fence prevented lambs from approaching the ewes at less than 1 m. A proximity zone near the ewes was defined (1 × 2 m). The location of the mother and the familiar ewe in the holding pens was alternated between tests. During 3 min were recorded: the proximity zone reached first, the latencies to enter each proximity zone, the total time spent in each proximity zone, and the number of bleats produced by the lamb while it was in each zone. All the lambs were tested 3 days before weaning, and 30 (n = 25), 40 (n = 15) or 60 days (n = 42) after weaning. Before weaning, there were no difference in the first proximity zone entered, but in the other variables lambs showed a strong preference for their mother rather than for the familiar ewe. Lambs still preferred their mother 30 days after weaning, although this preference was weakened. However, lambs tested 40 and 60 days after weaning did not show any preference. We concluded that after being weaned at three months of age, the preference of lambs for their mother in comparison to a familiar ewe decreases within 30 days, and finally disappeared 60 days after weaning.