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Worm Management

When we speak of worms in calves we are specifically referring to the parasitic worms that live in the fourth stomach (abomasum) of calves and cows.

There are many different species of worms that affect calves but there are three main species that cause most of the problems:

  1. Cooperia oncophera

  2. Ostertagia ostertagi

  3. Trichostrongylus axei

Each of these worms attach to the stomach wall and cause direct damage to the stomach lining, which impairs the calves ability to absorb nutrients from food. The main secondary effect of internal parasites in calves is appetite reduction – the calves simply do not eat as much – this has an even greater effect on calf performance than the direct effect of the worms themselves.

Treating calves is best done using an anthelmintic drench – oral products are generally the cheapest and best performing as most are provided in combination of two or more of the three main drench families.

Pour-on products are the most commonly used product for drenching calves HOWEVER, resistance to the main drench family in pour-ons (ivermectin) is incredibly common on MOST farms. If this is the case then use of either a combination oral or combination pour-on is necessary to continue efficient calf growth.

Injectable products are also commonly used in young calves at the same time as other procedures such as disbudding.

Drenching should be done according to what product is used, generally oral products need to be repeated every 4 weeks whereas the pour-on and injectable products have persistent activity and need only be repeated every 6 weeks.

If you have a regular drenching programme and you suspect resistance in your calves, please either arrange a veterinary visit or bring in a selection of fresh (caught straight from the calf) poo samples for us to test for the presence of parasites. If regularly drenched calves are still scouring, showing signs of ill thrift, or even not meeting growth targets, there may be resistance, or potentially another issue that needs addressing.

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