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Reduced survival of lambs from maiden ewes exposed to mature ewes pre-lambing

Robertson, S.M., Allworth, M.B., Friend, M.A.
Small ruminant research 2017 v.151 pp. 11-15
Merino, ewes, grazing, lambing, lambs, maternal behavior, pastures, rearing
The suboptimal survival of new-born lambs is a major source of reproductive inefficiency, is often lower in maiden (first-lambing) compared with multiparous ewes, and this may be associated with poor maternal behaviour due to inexperience. This study examined whether the survival of lambs from maiden ewes could be increased by exposing maiden ewes to multiparous lambing ewes in the month before lambing. Pregnant maiden Merino ewes (n=446) which had been mated at 18 months of age were allocated to three replicates of two treatments. During the month prior to the maidens lambing, control groups were grazed in paddocks each with 30 multiparous mature (5.5 and 6.5 years of age) Merino ewes which were due to lamb at the same time as the maiden ewes. The exposed treatment groups also grazed with 30 mature ewes, during which time the mature ewes lambed. All mature ewes and lambs were removed and the groups of maiden ewes grazed in separate 5.3ha paddocks from 10days before the maidens were due to lamb. The survival of lambs to marking age was lower (P=0.035) from maidens exposed to mature lambing ewes (0.73) compared with those that grazed only with pregnant mature ewes (0.81). The number of lambs reared per ewe lambing was not lower (P=0.274) from the exposed (0.92) compared with the control (0.98) ewes. This study showed that the survival of lambs from maiden ewes was reduced by exposing them to mature lambing ewes, and it is recommended to avoid grazing lambing mature ewes in the same paddock with maiden ewes in the month prior to the maiden lambing.