Layered Plan Needed To Fight BVD
Bovine Viral Diarrhoea (BVD) is sometimes viewed as a dairy industry issue, but the reality is that the disease can have serious consequences for beef breeding herds as well.
Strong prices for beef and lamb mean the marginal return on good animal health is excellent, says Boehringer Ingelheim Animal Health NZ.
Premium health and weight of stock, either for breeding or slaughter, are crucial, says the company’s technical veterinarian Richard Sides.
Most farmers know that to achieve these includes giving their young stock “a good drench,” he says.
But Sides says the start of a new season with a crop of young stock is also a good time to give the ‘good drench’ practice closer scrutiny. So he is urging farmers to develop, with their vet, a well-considered parasite control strategy that tackles resistance and effectiveness issues they may not know about in their herd or flock.
“Talk about triple resistance developing has been heard in recent years. That’s always a possibilitybecause the minute you put a drench product into an animal you are applying selection pressure on the parasite population inside it.”
However, he maintains there is no need to panic, even if farmers don’t know what their property’s status is.
“You don’t know what you don’t know, so the most proactive approach is to work with your vet to find out -- starting with faecal egg count (FEC) testing,” Sides says.
“Do this as a proper, planned reduction test (an FECRT), seeing what the populations are before and after a drench programme. Just doing a one-off post-drench check means there are simply too many possibilities you could get the wrong information, use the wrong product and possibly make resistance issues worse.”
He says a vet skilled in parasite management will establish what the efficacy of particular drenches is on the farm. They will also help work out ways to maintain a refugia population on the farm.
At its simplest, it will be determining a proportion of the flock or herd that is not drenched, to ensure resistant parasites are well diluted within the worm population. A key factor is ensuring that drenched animals, in particular lambs, do not go straight onto ‘clean’ (parasite larva-free) pasture.
“It is important to also ensure the refugia (undrenched) animals are mixed around the farm and across mobs to disperse that population of refugia parasites. And because of this, it is essential that the resistance status of those parasites is known – hence the need for proper reduction tests. These are easier and cheaper to do than most people realise”
Sides has also worked with farmers on other management practices that ultimately result in lower parasite populations in young stock.
“One large client was concerned this year about minimising numbers of tail-end lambs and they decided they wanted more feed on the hills earlier in spring to get the lambs fed better and away earlier.
“That led them to look at using fertiliser early to get early grass growth on steeper country for the single-bearing ewes, and rational pre-lamb ewe treatments on the flats.”
Time and attention to good dam health prior to calving and lambing will also reduce young stock’s vulnerability to parasite levels and the need to drench more than necessary.
“Having your ewes or cows in top notch condition means less stress in spring, better milk production, faster growth rates and getting young stock away quicker, reducing parasite exposure in the process.”
Avoiding risky management practices, like putting freshly drenched young stock onto brand new pasture where there is no refugia parasite population, is essential. Effective quarantine drenching is also vital for bought-in stock, again requiring knowledge of drench-status.
M.bovis is presently out of farmers’ hands, but responsibility for parasite management still lies with the individual farm and their personal vet.
“A sound parasite control plan will deliver returns within the season, by maximising growth of young stock and beyond as the risk of perpetuating resistant worm populations is delayed onfarm.”
