KEY POINTS:
Three into two does not go, so scientists are trying to breed ewes with four nipples instead of two.
New Zealand sheep have become more fertile over the past 10 years, and more ewes are having triplets.
But female sheep have only two nipples, so one lamb in a set of triplets can miss out on getting life-sustaining milk from its mother.
"A triplet, if he is the runt of the litter, is usually doomed," said AgResearch Invermay scientist George Davis. "If one triplet is light, his two litter mates can bully him out."
Dr Davis has started searching for ewes which have four working nipples, with the aim of developing a flock from which rams can be bred to pass on this trait.
He said sheep flocks 10 years ago were lambing at 100 per cent, but today's average lambing was more than 120 per cent - 100 ewes having 120 lambs or more.
Farmers have managed the problem by pregnancy scanning ewes before lambing, separating those carrying triplets or quadruplets and ensuring they have plenty of grass so they produce enough milk.
Twenty years ago, scientists created a multi-nippled flock as part of research into the Booroola breed of sheep, but Dr Davis said farmers lost interest in the breed, known for breeding large numbers of lambs.
Improved lamb prices have revived interest in ewes which breed many lambs.
The earlier research suggested a ewe with four functional teats could produce more milk than a ewe with two.
Dr Davis said a dairy cow, which has four teats, produced 40 per cent of its milk from two mammary glands and 60 per cent from the other two.
Dr Davis is hoping sheep carrying the trait will eventually be available to farmers.
- OTAGO DAILY TIMES
