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Drenching calves: What to consider?

Drenching calves: What to consider?

Drenching calves: What to consider?

Calves are unlikely to have a worm burden until they have been grazing pasture as a significant part of their diet for at least one month. This usually means calves are at least eight weeks old and are weighing somewhere between 70 to 100 kg depending on genetics and age.

When calves ingest infective worm larvae in significant numbers, their feed intake drops and daily liveweight gain is impacted. Regular drenching of calves throughout the summer and autumn minimises the impact of ingesting high larval numbers and more importantly, helps lower worm egg output from adult worms in the gut system of the calves feeding on contaminated pastures.

A safe and effective drench option for the first drench is a BZ/Levamisole oral combination such as VETMED’s Combomax Oral. Be sure to avoid any product containing abamectin in calves under 100 kg due to toxicity risk.

Drenching at 28 day intervals throughout the summer and autumn is necessary to obtain a balance of not over drenching but allowing some refugia to occur. Once calves reach 100 kg, use a triple combination oral product such as VETMED Triplemax Oral.

It is best practice to perform a 10 day post drench check to assess that the drench used is working effectively.

Due to the size of animals in autumn, changing to either an injectable or pour-on product may be considered. Whatever product is chosen, it must contain levamisole to control Cooperia worms.

Avoid grazing large numbers of calves on the same paddocks year on year as there can be high residual infective worm larvae present. Cross grazing with older cattle or sheep reduces the parasite challenge without having to solely rely on drench.

To put an effective parasite programme in place, contact your local PGG Wrightson Technical Field Representative.