Making improvements to sheep management and housing has helped a Welsh sheep farmer cut the mastitis rate in his flock by a third.

Mastitis had been a major cause of losses in Ryan Morris’ flock of nearly 1,000 ewes at Maestanyglwyden near Oswestry.

Around 10 per cent of the flock – 90 to100 ewes – would get mastitis every year.

“We had problems throughout the year, although the spring was the worst time,’’ says Mr Morris, who took on the farm from his grandfather five years ago and now farms with his partner, Rebecca Greaves.

Milk sampling had shown the presence of the mastitis-causing bacteria, Staphylococcus aureus (S. aureus) and Mannheimia haemolytica.

Farming Connect enabled an on-farm trial alongside the farm’s vets, Cain Farm Vets, to establish the factors influencing the high incidence of mastitis and to help inform a plan to reduce rates.

The trial monitored the mastitis incidence rate in 439 twin-bearing ewes from the March-lambing flock.

Blood sampling was used to assess flock nutrition three weeks before lambing; this established that the diet was meeting the protein and energy requirements of the ewes during late gestation.

Ewes were vaccinated with Heptavac P, a clostridial vaccine containing Mannheimia haemolytica, and a booster administered four weeks before lambing.

Mr Morris made several improvements to his housing to reduce stocking density – floor space was increased by a sixth to reduce the pathogen load within the shed.

The number of dedicated small pens for freshly-lambed ewes was increased so that ewes could be moved out of the main lambing area into clean pens within two hours.

Close attention was paid to cleanliness – all staff wore arm-length disposable gloves for lambing and short gloves for jobs such as putting lambs to suckle, to reduce the risk of bacteria spreading between sheep and onto teats.

When the study concluded in July 2021, the overall mastitis rate was found to have reduced from 10 per cent to 6.8 per cent.

Alana Jackson, of Cain Farm Vets, the vet who instigated the trial, puts this down to a combination of factors, notably reduced stocking density and improved hygiene.

“Reducing the pathogen load that ewes are exposed to at point of lambing, when their immune system is most suppressed, will have had a big effect,’’ she advises.

Continuing to feed ewes up to peak lactation and until six weeks after turnout, will also have helped by ensuring milk production was sufficient, she adds.

If a ewe isn’t producing enough milk, lambs will suckle more frequently and this can cause teat damage, increasing the risk of a ewe developing mastitis.

Ms Jackson says mastitis in ewes is more of an issue on some farms than others.

“It is a multi-factorial disease which makes control difficult,’’ she admits.

“This field trial just shows that ‘tweaking’ several aspects of management in the flock has had a positive effect. However there is no ‘silver-bullet’.’’

Testing the vaccine

Another part of the trial was to vaccinate ewes with a vaccine that protects ewes from mastitis caused by S. aureus.

Half the study group was vaccinated.

Ms Jackson says analysis of the data showed that there was no statistical difference in mastitis rates between the vaccinated and unvaccinated groups but she warns against drawing conclusions from this due to the study involving only 439 ewes.

“The positive effect of the vaccine may be subtle, and having more ewes in the study may have shown that vaccinated ewes did have a significantly reduced mastitis incidence rate,’’ says Ms Jackson.

She believes that boosting the ewes’ immunity to S. aureus with the vaccine will have improved immunity.