Sheep study finds young mothers have more lambs

(PhysOrg.com) -- New research suggests that being a young mother is not a bad thing for a sheep and may mean ewes have more lambs that are just as healthy than those that are older when first bred.

There is ongoing debate about whether lambing as a yearling is in the long-term interest of the animal, with questions over wool quality and the size of subsequent litters.

The research has been something of a family affair, with Associate Professor Patrick Morel, his wife Jenny Wickham, her father Dr George Wickham and the couple's son, Jolin Morel, authoring a paper called Effects of birth rank and yearling lambing on long-term ewe reproductive performance presented at the New Zealand Animal Production Conference.

“There is a feeling that if a ewe gives birth as a yearling it may take them too long to recover, which affects them in the future,” Dr Morel says. “So there would be a trade-off with getting that extra litter at the younger age. Currently only 30 per cent of sheep farmers mate yearling ewes because of these concerns.”

Research carried out by Dr Morel’s colleague, Associate Professor Paul Kenyon, showed that two-year-old ewes that lambed as hoggets (yearlings) were less likely to have multiple births than those having their first lambs. Ewes reach sexual maturity at about six to eight months of age and give birth to between one and four lambs (usually twins) each year after a five-month gestation.

Dr Morel recorded the 250 litters born at his farm over the past decade. He found that while ewes that gave birth as hoggets (yearlings) did have smaller litters the next year, after four years they had produced more offspring overall.

Dr Morel is director of animal nutrition in the Institute of Food, Nutrition and Human Health whose main area of research is animal growth and nutrition. He says he wanted to involve his family in a scientific study. “My father-in-law gave us 25 ewes to start our flock, my wife managed the flock, I did the number crunching, my father in-law made sure the science was correct from his point of view, and my son helped collecting all the data.”

Dr Wickham was an associate professor and sheep and wool specialist at Massey for many years, so was ideally placed to contribute. “But we all have a Massey connection," Dr Morel says. "My wife has a degree from Massey in agricultural science and Jolin is currently studying chemical engineering.”