Farmers in southern New Zealand identified areas where knowledge was needed to improve the outcomes from mating ewe lambs at seven months of age. Anecdotal evidence suggested that ewe lambs growing rapidly at mating were less likely to become pregnant. Farmers recorded ewe lamb live weight in March and late May, and pregnancy diagnosis data. Data analysis showed no relationship between liveweight gain and number of ewe lambs pregnant. Farmers retained their original views that liveweight gain before and during mating should be below 100 g/d. Feeding levels in late pregnancy were considered to influence ease of lambing and lamb survival. The amount of feed offered to ewe lambs in late pregnancy on eight farms was compared to tailing percentage and lamb mortality. Feed offered to single bearing ewe lambs in late pregnancy ranged from 0.75 to 1.6 kg dry matter/d. Late pregnancy feed allowance and lamb mortality were unrelated. Analysis of winter liveweight gain data from both on-farm studies and survey results over two years showed that winter liveweight gains of 10 to 14 kg, including conceptus weight, minimised lamb losses (P <0.05). Farmers changed management practices to improve winter liveweight gain, and improve the accuracy of late pregnancy feed allocation.

DR, Stevens

Proceedings of the New Zealand Society of Animal Production, Volume 70, Palmerston North, 113-117, 2010
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