As lambs begin to reach sexual maturity, Beef + Lamb New Zealand is recommending farmers draft male lambs out from ewe lambs to avoid any unplanned pregnancies.
Ewe lambs can reach puberty from as early as five months, and this is influenced by breed, genetics, weight and nutrition.
Beef + Lamb New Zealand’s Senior Advisor Biosecurity and Animal Welfare Will Halliday, suggests drafting any non-replacement ewe lambs intended for sale as soon as they reach 35-40kg, as their chance of conception increases at these weights.
“At lamb shearing, ask shearers to mark any male lambs that might inadvertently got into ewe lamb flocks as they come across the board.”
For farmers buying in store lambs, it is a good idea to ensure that all the lambs are correct gender.
Arable farmers at a recent B+LNZ and Foundation for Arable Research combined field day said unplanned lambs were a huge issue for many of them.
One farmer said they get around this by separating the ewe and ram lambs as soon as they arrived on-farm. They also sex every lamb on arrival, as they have found ear marks to be unreliable.
Inadvertently pregnant sheep are also a problem at saleyards and processors and can result in breaches of Animal Welfare Regulations.
Cryptorchids
Cryptorchids behave like rams over mating, mounting other stock, curling back their upper lip with their head held high and displaying aggressive behaviour.
They may also have pizzle stains, or urine-stained wool around the pizzle area.
Cryptorchids can inseminate ewes and should be removed from the flock.
Checking ewes before sale or processing
Halliday says not all ewes are pregnancy scanned, so he recommends farmers carry out a full assessment of stock before sending them to sale or slaughter. Particularly over the winter months and into spring.
Typical signs of an impending lamb include a firm udder and teats, a slackening and swelling of the lips of the vulva and abdominal tightness. (The belly of a pregnant ewe is firmer when palpated compared to the belly of an unbred ewe).
For more information go to: Limiting the risk of unplanned and late pregnancies in sheep