Milking sheep potential problems afoot

In New Zealand, however, we are far more familiar with sheep being raised for their meat and wool – but there is growing interest in farming dairy sheep.

Sheep milk is nutritious and is richer in vitamins A, B and E, calcium, phosphorus and magnesium than cow's milk. It contains a higher proportional of short- and medium-chain fatty acids (the "good" fatty acids). The fat molecules in sheep milk are smaller than those in cows' milk so are more easily digested.

While lactating ewes of any breed can be milked there are specialised dairy sheep breeds, such as the Chios (from Greece) and Awassi (in New Zealand, but originally from Israel). These can produce about four times more milk per lactation than meat and wool producing breeds.

Unfortunately, sheep and goats are susceptible to getting footrot – a painful infection of their hooves. It is a major welfare issue; causing significant economic cost to sheep production worldwide.

In an international collaborative study with scientists from the School of Veterinary Medicine, at the Aristotle University of Thessaloniki in Greece, Professor Jon Hickford of Lincoln University studied genetic variation in a gene marker for footrot resilience in the Greek Chios sheep.

The research found that the breed was susceptible to footrot and that the gene-marker test developed in New Zealand was a useful tool for finding sheep that were less susceptible to the disease. This compares with what Hickford had already found in Awassi sheep in New Zealand.

"This suggests that if we intensify and farm milking sheep then footrot may be an issue," explains Hickford. "Farmers would need to be diligent about checking susceptibility to footrot of any dairy sheep, especially any sheep imported into to New Zealand to build a sheep milking industry.

"While it's true, we don't have Chios sheep here, the observation that the footrot-gene marker test we have developed works in them and the Awassi, says it would be a useful tool in any expanded milking sheep industry in New Zealand."

Hickford says, to start with, farmers could get any rams they are considering purchasing tested to ascertain their footrot susceptibility before making a final decision.

"They could then selectively breed for increased tolerance to the disease, which would reduce any adverse cost or welfare issue stemming from a footrot outbreak or ongoing disease challenge," he adds.

"This is an opportunity for farmers contemplating the change to a new form of sheep production, to capitalise on the considerable research already undertaken in this field."