Significant 25% increase in parasites in sheep year-on-year

07 April 2021 

Dunedin NZ: A combination of warm and wet weather over the New Zealand summer has created optimal conditions for parasites to thrive, with year-on-year analysis of faecal egg counts showing stock across the country are facing a significant increase in parasite challenge.

Techion conducts thousands of FEC tests at its laboratory at Invermay and analyses thousands more from farms across the country through its digital FECPAKG2 platform. Through the period from January until February 2020 FEC counts were 1515epg (egg per gram), for the same period in 2021 the average is 1906epg, which is a 25% increase in parasite egg output.

Techion founder and CEO Greg Mirams said the findings represented more than 15,000 FEC tests taken on farms from Southland to Northland. Underlining the increase is the fact that on average collections have occurred 11 days earlier this season than they did in 2020.

He said the rise was due to this year’s favourable feed conditions with many farmers holding lambs for longer to grow them to heavier weights. “Summer has produced an abundance of quality feed, so stock have generally been protected from the impact of parasites. However, the parasites have been laid down on pasture and are waiting for the autumn pinch conditions to occur. The weather factors and high lamb numbers will combine to create a significantly higher parasite challenge to all stock through late autumn early winter period,” he said.

“It’s vitality important farmers look out for the signs of high larval intakes through over the next two-three months. This is particularly relevant for young stock.”

Mirams explained that signs of stock being impacted by high larval challenge include weight loss and poor condition where animals have a ‘shelly’ appearance, lethargy and in some cases an increase in dags and scouring. These signs can occur even when the animals have regularly been drenched and have adequate feed, he said.

Mirams said farmers should remember to interpret FEC results at this time of year with caution. This is because animals fighting high intakes of larvae may be impacted before the larvae have matured into egg laying adult parasites in the gut of the animal and are revealed in a FEC test.

Farmers can deal with this emerging challenge as there are proven steps they can take to minimise the parasite threat. These include reviewing grazing options for young stock and trying to graze this vulnerable group on lower risk pasture. Low risk pasture includes re-growth autumn cut silage or pasture where ewes or cattle have previously dominated the grazing. A key is avoiding grazing young stock on areas that have carried high numbers of lambs earlier in the season.

Additionally, Mirams said farmers should not stretch out drench intervals through this period with young stock, while remembering that an effective drench will ‘flush’ out what the animals are carrying at that time, it will provide limited protection against a sustained high intake of parasite larvae.

While young stock are the most vulnerable, it’s important not to forget 2ths and lighter ewes as they approach tupping. Regular FEC testing of these stock may highlight a developing parasite issue. The cost of an undetected parasite challenge can be high, as parasites will negatively impact conception rates through the tupping period.

He said that during this type of season the value of using genetically superior WormFEC rams that have been breed for resistance to parasites really pays off. As Gordon Levett, the godfather of breeding for resistance steps back from active breeding, he shares some results that present a compelling case to pursue genetics as part of the parasite solution. Put simply, genetics that reduce parasite egg output mean there are less larvae on pasture. Low pasture larval intakes will translate to animals growing faster and requiring less drenching.