Speaking on a Beef + Lamb New Zealand Scene + Herd podcast, Professor Paul Kenyon from Massey University says large farm-scale studies have shown that mid-pregnancy shearing (between 50-100 days) can be valuable tool to improve foetal growth in twin and triplet lambs so they are born within the optimal birthweight range. This in turn enhances lamb survival, but this survival response will only occur if the ewe is well fed and has body reserves available- so a minimum Body Condition Score of 2.5.
“You’ll only get an increase in survival response if she is fed well, so if you’re feeding to pregnancy requirements.”
This also builds a case for not shearing lighter condition ewes at mid-pregnancy.
Professor Kenyan says the idea of shearing ewes mid-pregnancy in the assumption that they would seek shelter at lambing is flawed.
If the ewe is shorn with a cover comb, as is required by the Animal Welfare Act, then by the time the lamb is born she will have around 3cm of wool. At just 2cm, a ewe is thermal neutral so is neither hot nor cold at zero degrees with no wind chill. At 3cm, the ewe will be unaffected by cold, rain and windchill.