Sheep bearing research underway

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Farmers who dealt with severe bearing outbreaks this spring will be pleased to know a major project has been set up to try and crack the problem.

Bearings are to be monitored on 140 sheep farms in Hawkes Bay and Southland as part of a study funded by AgMardt, Meat New Zealand and WoolPro.

WoolPro’s Gore-based extension specialist Sharon McIntyre says bearings (prolapsed vaginas) were a major concern in parts of Southland this spring. In other regions, outbreaks were sporadic.

Across the country, the condition is thought to cost sheep farmers about $30 million a year in lost production.

"Few farms are without bearings altogether. It’s one of those extremely frustrating conditions that fluctuates in severity from year to year but only rarely goes away," she says.

They normally turn up about a fortnight before lambing, mainly in ewes pregnant with twins. Some farms get them worse than others and until now no-one has known why.

She says scientists and farmers have for many years looked at possible causes without success.

For instance, recent research by AgResearch’s Dr Greg Lambert -- also funded by WoolPro and Meat New Zealand -- has confirmed that bearings are not necessarily related to liveweight, nor the previous number of lambs born from a ewe.

"It now appears that a number of factors must be responsible, which is why the latest research involves so many farms in different parts of New Zealand," Ms McIntyre says.

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Hawkes Bay veterinarian Richard Hilson is leading the bearing project team. It includes vets from Massey University and Andrew Roe from Central Southland Vet Services.

They are collecting data on a wide range of animal and farm management practices, and each farm’s physical characteristics, to work out possible causes.

"By monitoring factors such as changes in body weight, amount of exercise, feed levels and mineral balances in the sheep, they hope to get a better understanding of factors that lead to bearings and ways to prevent them," Ms McIntyre says.

This follows work by AgResearch two years ago which looked at possible links between bearings and magnesium and calcium levels in pregnant ewes. The trial was inconclusive, because the year was a quiet one for bearings.

Until the causes have been defined, farmers are left to deal with bearing outbreaks as best they can.

For economic and humane reasons, Ms McIntyre says cases need to be detected and treated promptly. There’s little chance a ewe will successfully get in lamb in the future if the prolapse is left to dry out.

She also cautions farmers against limiting feed in late pregnancy in an attempt to reduce the incidence of the condition. There’s no evidence the strategy works.

"It usually only leads to a reduction in lamb weights and vigour at birth."

AgResearch’s David Stevens says a good condition score (3.0 or above) should be maintained to ensure ewes milk well and their lambs grow quickly.

"Research shows that 60 per cent of lamb weaning weight is determined by ewe body condition score at lambing," he says.

Comprehensive guidelines for dealing with bearings can be found in "A Guide to Improved Lambing Percentages", available at any WoolPro or Meat New Zealand office.

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