War on worms

Intestinal worms in livestock cause large production losses, and an earlier survey showed a large percentage of farms suffered from some drench resistance.

These messages have been around for a while now, but still farmers are reluctant to change their farming system to minimise the damage.

Instead they have relied on pharmaceutical companies to produce new products to solve these problems. However costs continue to erode profits from most farms and operating "smarter with knowledge" from fieldays such as these will give a better return.

Minimising medicinal intervention could be a condition in future for the sale of quality products, and farmers that upskill in these areas will lead the pack.

Strict quarantine systems should be adopted on finishing farms to reduce worm infestation of stock, Taranaki beef and sheep farmers were told last week.Conducted by Feilding veterinarians Trevor Cook and Greta Baynes, they said robust quarantine procedures should be applied on finishing farms for maximum liveweight gain reports The Taranaki Daily. "The finisher is at risk of animals that have a high level of resistance because farmers don't do drench tests. Quarantine procedures are vital for the finisher because significant numbers of animals from other farms pose high risks."Animals should be drenched on arrival at a finishing farm and held in yards for 24 hours to minimise the chance of introducing new worms to paddocks, he said.

Most farmers have no idea which drench is effective. "It's only when drenches are failing badly that it's obvious they're not working. Without doing a test, there is no evidence that resistance is there."The challenge is to have drenches that will be effective in 10 years' time. New drenches are coming but the cost of getting them to market is huge. The biggest opportunity is to use existing drenches smartly so that they are cost-effective."

Mr Cook said that even though the failure rates of pour-on drenches were documented, they continued to be used. Drenching adult animals with pour-ons would lead to drench-resistant worm. He said the Wormwise message of managing worms to protect production applied to dairy farmers as well as beef and sheep farmers.

Grazing dairy heifers and raising bulls to 18 months or two years of age had become an important part of beef farming, but if the animals arrived on a farm loaded up with worms, productivity and profitability would be limited. Ms Baynes said a drench test every three to five years would determine the level of worm resistance in stock and would cost a maximum of $1500. A 2005 survey had shown that 75 per cent of sheep farms and 96 per cent of beef farms had worms resistant to at least one drench family, she said.

Farmers should avoid drenching more frequently than every 28 days, should apply the right amount of drench for the animal's weight, and should calibrate their drench guns.They should also beware of long-acting products which were more likely to select worms that were drench-resistant, she said. Effective combination drenches were better, and could last 20 to 30 years if used in conjunction with a worm population not exposed to drenching. Not all stock should be drenched, Ms Baynes said. Leaving 5 to 10 per cent untreated would help the sustainability of drenches.

The animals with the best liveweight gain should be those that were not treated, she said. A mixed-age ewe in good condition was also at low risk of worm infestation. Sharing lamb grazing with undrenched ewes helped to increase lamb growth rates.An exit drench in autumn would get rid of the resistant worm population, she said.