CRV Ambreed offers genetic solution to increase FE tolerance in dairy cattle

category Genetics

New Zealand dairy farmers must act now and use the right targeted genetics to breed cattle that are more resilient to facial eczema.

That’s the message from CRV Ambreed’s research and development manager Phil Beatson who believes the dairy industry could learn a great deal from the sheep industry to successfully increase tolerance this debilitating disease long-term.

Facial eczema (FE) is not only harmful for animals, but also incredibly stressful for farmers when their stock is affected.

It is caused by a toxin (sporisdesim) produced by the spores of the fungus Pithomyces chartarum growing on pasture. The fungus grows in the dead litter at the base of pasture in warm moist conditions, and when ingested by cattle or sheep, damages the liver and bile ducts.

Higher humidity has increased the number of toxic spores in pastures this year, resulting in a spike in the number of FE cases in the North Island and parts of the South Island.

Beatson says the fact that the Grey Valley has experienced some severe outbreaks for the first time, and this seems the worst for several years throughout the North Island, indicates what the future may hold with global warming.

“For every three in 100 cows with clinical FE, it is estimated up to 70 per cent of the herd may have subclinical symptoms. You won’t necessarily see the disease in cows with subclinical symptoms, but it will be damaging the liver and negatively impacting milk production,” Beatson explains.

“With climate change, this problem is only going to get worse. As an industry we can’t rely on short-term measures to treat FE any longer.  This is already a huge economic and animal welfare issue and genetics provides the only long-term solution to the problem.”

Using CRV Ambreed’s current FE tolerant sires will typically breed off-spring that are 30% less reactive to a FE challenge, compared to the average bull.

But as the sheep industry has proven, targeted genetics must be a part of the farming toolbox year-on-year to reduce the occurrence of the disease.

Currently the most common way to treat FE is by dosing animals with zinc, but Beatson’s concern is that zinc is a heavy metal that will be going back into the environment.

“How acceptable is it from an environmental point of view? And how acceptable is it to buyers who purchase milk from cows dosed with a heavy metal? Genetics is a safe, environmentally sustainable and more economically sustainable option.

“Genetics will not provide a complete guaranteed solution, but it will breed tolerance which will increase over time. For example, sheep bred for FE tolerance over 30 years ago are now nine times as tolerant to a FE challenge than their 1980’s ancestors. A genetically improved herd will need less zinc and other treatments than the typical animal, which saves the farmer this expense,” he adds.

There is currently a shortfall in the understanding of what FE actually costs farmers and the industry. CRV Ambreed is currently working with AgResearch to quantify the costs in lost production, weight loss and death of stock.

“Because many animals with subclinical symptoms go undiagnosed and untreated, it is hard to quantify the economic impact of FE on the dairy industry.  Some estimate that lost milk production costs the industry hundreds of millions per year, depending on outbreaks and weather,” Beatson says.

Research and development completed by CRV Ambreed and its research partners resulted in the ability to identify FE tolerant bulls, which were first marketed in 2014.  As pioneers in this area, CRV Ambreed remains the only provider in New Zealand with a genetic solution to increase tolerance of FE.

As CRV Ambreed’s FE breeding programme continues to develop, bulls will become more and more tolerant, improving herd health resulting in longer lasting, more productive herds.

“While it’s too late to manage this year’s FE outbreak using genetics, dairy farmers can include FE tolerant bulls in this year’s matings and start building greater tolerance for the future,” Beatson adds.

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