News & Advice

Coccidia and deciding when to start drenching calves

Sep 4, 2019 | Dairy, Dairy Animal Health & Welfare, Young Stock

The season of Rotavirus,  Cryptosporidium,  E. coli  and Coronavirus is almost over. Whether you’ve had a good year with calf scours, or a bad year, there is still more to consider!

Don’t forget about  coccidia.  It is more common than you think! Although we may not see clinical disease (straining, blood scours and poorly calves), calf growth rates after weaning may be checked by this parasite if untreated.  Coccidia  is usually controlled by a drug (coccidiostat) contained in most (but not all) milk powders and in most (but not all) calf meals. This drug is highly effective at preventing  coccidia  if the calves consume enough meal.
There are a few common scenarios when we see  coccidia  in dairy calves;

  • Switching to a cheaper brand of milk powder or calf meal that doesn’t contain a coccidiostat, 
  • reducing the meal suddenly after weaning off milk, or stopping feeding meal too soon after weaning, 
  • mobs of calves with variation in size so therefore huge variations in meal (and therefore coccidiostat intake), or 
  • calves going to a runoff block around weaning time where they always graze the same paddocks when they arrive. 

There is a very effective drug to treat coccidia, and using it at the high risk time for your calves as a preventative, or after you have identified it on a faecal sample will reduce the negative impact on this group.


And what about worms? When do we start drenching? 

The best way to assess if calves need drenching is to take fecal samples from multiple calves.


Why drench earlier than you have to? 

In general, there are a few rules to follow. Calves don’t need to be drenched until they have been eating a significant amount of grass for 3-4 weeks; if you’re wanting to drench calves while they are still on milk you should really talk to your vet first. Abamectin has a very low safety margin; it is really easy to overdose/kill calves (this is why we recommend a safe oral product).


Signs and symptoms to watch out for: 

  • Mucus in faeces 
  • Blood in faeces 
  • Scours (variable appearance) 
  • Straining to poo 
  • Ill thrifty calves (which may or may not have signs above) 
  • Poor doing calves in spite of receiving a worm drench 
  • Not reaching target weights around weaning time 

If you notice that your calves are displaying any of these signs, have a chat with your vet to determine what to do next. Treatment is often highly effective.

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