For most sheep farmers income is determined by the total weight of lamb weaned which is, in turn, a factor of lambing % and lamb growth rates. While the potential lambing is determined at mating time how well the ewes are managed in the last month of pregnancy has a large influence on both lamb survival (and hence final lambing %) and growth rates.
Something like 60% of a lamb’s growth rate up until weaning is determined by how its mother has been fed in the 4 - 6 weeks before the lamb is born. This is because underfeeding in this period when close to two thirds of foetal growth occurs, reduces udder development, milk and colostrum production, lamb birth weight, vigour and early suckling behaviour.
One month out from lambing you are looking at 1.6kg DM/day of reasonable quality pasture for a 70-75kg single bearing ewe and 1.9kg/day for a twin bearing ewe. At full term this has risen to 1.8 - 1.9 for the single and 2.3 - 2.5kg DM/day for the twin. Shearing during this period will also dramatically increase energy requirements often when feed is tight, so is probably better carried out earlier (midwinter).
Multiples, because of rumen capacity (fitting it all in) problems need high quality feed available – the best pasture will be the previous seasons young grass paddocks or fresh regrowth. Barley is a good supplement at this time – start off gradually at 50gms/head/day getting up to 200gmms for twins and 250-300 for triplets over a period of 7 - 10 days. These ewes should not fall over from a metabolic disease or get too many bearings as long as a feast/famine feeding regime is avoided.
Written by John Smart BVSc
Extract from July 2008 - Sheep Newsletter
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