Controlling Parasites at Housing

Cattle finishing the grazing season need to be treated for parasites they have acquired during their time at grass.  Once animals are correctly treated for these problems at housing they will remain free of parasites until they go back to grass.  Don’t forget to also treat for external parasites (lice and mange). Selection of the correct product or combination of products will save time and money.  Remember to follow product instructions carefully, including meat withdrawal times, and give the appropriate quantity of the dose to each animal.  Weigh cattle to ensure you are not under or over dosing.

Key points:
• Don’t be complacent due to a dry summer. Fluke and worms are present in large numbers on grazing ground; housing is an excellent time for treatment.
• Ensure to follow product instructions carefully including meat withdrawal periods.
• Weigh cattle to avoid under or over dosing

Parasites to target at housing
1. Liver Fluke

Even a low level of fluke infestation can reduce weight gain by 8-9% and it follows that higher burdens will have a devastating effect on cattle.  Research shows that high levels of fluke infestation in cattle can reduce weight gains by a staggering 28%. Treating for fluke represents a strong return on investment. 

Despite a dry summer contamination of pastures remains very high with areas of the country that have traditionally had no problems with liver fluke also being affected.   A fluke survey carried out in one particular meat plant in early September shows that 84% of cow’s livers and 49% of cattle livers were condemned. One reason for this may be related to the fact all farmland is being grazed this year due to the dry summer, fodder shortages in early summer and then extended growing season we are seeing now.

Key point: Liver fluke is widespread; don’t assume you don’t have a problem just because you have a ‘dry’ farm. Unlike with worms, adult animals cannot build up immunity to liver fluke.

There is a large range of active ingredients and products that are effective against adult fluke but only some are effective against immature fluke.  The most effective treatments are those that contain the oral form of the active ingredient Triclabendazole (e.g. Fasinex) but the next best are those that contain the pour-on forms of Closantel (e.g. Closamectin) and Triclabendazole (e.g. Cydectin Triclamox). These products have activity against immature liver fluke and can therefore give a good level of control when used shortly after housing (from 2-7 weeks post housing).  Pour-on products are the best choice for animal welfare and human safety. 
 
There are a number of other cheaper options but you need to treat animals twice or wait up to 12 weeks after housing, depending on the product, before you use them to ensure the animals are covered against fluke for the entire housing period.  During this delay the liver fluke population within the animals can cause significant damage. It is recommended to use products with different active ingredients every couple of years to prevent resistance developing/building up.

Liver Fluke Active Ingredient Efficacy Table
 

 
Liver Fluke

Key point: The pour-on forms of Triclabendazole (Cydectin Triclamox) or Closantel (Closamectin) are the products of choice against liver fluke as pour-on products are the best choice for animal welfare and human safety and they have activity against immature as well as adult fluke. Other active ingredients are only active against adult fluke, leading to the requirement for a two dose programme.

2. Worms
Cattle built up immunity to gut and lung worms as they get older.  Therefore it may be unnecessary to treat older animals.  However, due to the high levels of grazed grass in the diets of cattle in Ireland, a high worm challenge is often present meaning a production penalty in terms of live-weight gain. There are a large selection of products can be used at housing (watch withdrawal times); make sure to use products that are effective against Type II Ostertagia.  


Lungworm

Stomach Worm

Key point: The majority of livestock, are likely to require a worm dose at housing. Make sure your housing wormer covers type II Ostertagia and you observe the meat withdrawal times.

3. Lice and Mange
Numbers can build up rapidly in housed cattle.  Ivermectin products (e.g. Mastermectin or Noromectin) or combination products (e.g. Closamectin) that kill worms are suitable but note injections will not cover biting lice (sucking lice only) while pour-ons do.  Specialist pour-on products are also very effective e.g. Ectospec.

Treat animals shortly after housing before heavy infestations develop, and repeat 3-4 weeks later as most products are not effective against the eggs of biting lice.

 
Lice

Key points:
• Injections will not cover biting lice, a pour-on is required for complete cover.
• Treat animals twice-shortly after housing before heavy infestations develop and again 3-4 weeks later once all the eggs of biting lice have hatched.

Plus/Minus Rumen Fluke
Rumen Fluke has increased in importance in recent years and significant levels of infection have been reported in a small number of ‘hot-spot’ areas.  Oxyclosanide e.g. Zanil is the only active ingredient known to be effective against Rumen Fluke.  In most areas treatment for Rumen Fluke is unnecessary but it should be used if there are reports of it in the area or where stock have been bought in (as you don’t know the full history of these animals).

• These options are recommended as they are more effective against liver fluke (full kill at much earlier stage), less stressful on the animals and less labour intensive.
• For best results wait 5-7 weeks after housing before treating (remember animals need to be treated twice for external parasites: treat 3-4 weeks before or after with a specialist lice treatment e.g. Ectospec).
• Add Zanil or Levacide Diamond for Rumen Fluke if required (do not treat with two fluke products on the same day-leave two weeks between applications)

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