Parasite Control – Growing Cattle at Grass

Given the huge variation and local unpredictability of weather seen across the country this winter, it will be hard to predict the affect this may have had on parasite survival rates; however 2016 plays out it would be hard to believe that the challenge will be as low as it was in 2015. This coupled with the need for animals to utilise grass as well as possible, it would likely be too large a gamble not to control parasites well during the season.

Cattle Parasite Control

Parasitic gastroenteritis (PGE), is caused by gut worms (Figure 1), mainly Ostertagia ostertagi, which lives in the abomasum of grazing cattle. PGE represents a threat to the health, welfare and production of livestock, giving a loss of productivity in both the beef and the dairy industry: impacting on weight gain, carcass quality and milk production.1

Ostertagia Ostertagi

Figure 1 – O.ostertagi burrowing into the abomasum

Therefore, it necessitates a farm based assessment with SQPs (suitably qualified persons) and vets to determine the risks and the growth requirements for the farm when creating a control strategy.

Broadly, there are two options that can be taken. One is to treat cattle for gut (and lung) worms in the early grazing season to reduce pasture burden and therefore infection later on.  Alternatively, there is the option to closely monitor cattle through the grazing season for any signs of worm burdens. Ideally, young cattle should be regularly weighed and benchmarked against target growth rates typically 0.7 to 0.75kg/day for young stock from grass.

Whichever option is followed, ensure you follow the COWS (Control of Worms Sustainably) best practice principles for the most effective use of cattle wormers. Target the animals that are at risk, ensure they receive the correct dose by weighing each animal and check dosing equipment.

For uninterrupted growth through the grazing season, thereby high grass utilisation, two options that offer immunity development and minimal handling are a pulse-release rumen bolus or long-duration 10% moxidectin treatment.

From Autoworm™ First Grazer, seven doses of oxfendazole are released, at three-week intervals, killing all common roundworms that cattle may be carrying, including lungworm. The active ingredient has no residual action, so cattle are exposed to worm challenge during each 21 day interval between pulses, thereby stimulating an immune response (Figure 2).


Figure 2 – Autoworm bolus

Also offering season-long protection in set stocking situations is a single treatment at turnout with CYDECTIN® 10% LA for Cattle given as a sub-cutaneous injection in the base of the ear (Figure 3).

Base of ear injection technique

Figure 3 – Base of ear injection technique

The active ingredient moxidectin is distributed through the bloodstream, so worm larvae need to penetrate the gut wall - creating trickle exposure to the pathogen and thereby stimulating an immune response - before being killed (see Figure 4).

Zoetis Lungworm Diagram

Figure 4 – Development of immunity while still controlling worm burden

Specifically with immunity to lungworm in mind, the gold standard recommendation is to vaccinate. However, unvaccinated cattle can develop natural immunity under both the programmes above through the trickle exposure to worms present on pasture.

For farmers concerned not to over-use the ML wormer group - which, for use in cattle, includes ivermectin, doramectin, eprinomectin and the highly potent moxidectin, alternating use of Autoworm one year and CYDECTIN 10% the next is a valid strategy for season long control.

Whatever options you have in mind, advanced planning is the way to maintain good animal health and maximise productivity from grassland. This time of year is ideal for a chat with your vet, SQP or ideally both of them together, and then draw up a summer health protection plan for responsible and effective use of medicines integrated with other management techniques.

1.Charlier et al. (2009) Veterinary parasitology 164, 70-79

CYDECTIN® 10% LA Solution for Injection for Cattle contains moxidectin. POM-VPS. AUTOWORM™ Finisher/First Grazer contains oxfendazole POM-VPS. For further information please see the product SPC, or contact your veterinary surgeon, SQP or Zoetis UK Ltd, Walton Oaks, Dorking Road, Walton on the Hill, Tadworth, Surrey, KT20 7NS. Customer Support 0845 3008034. Always seek the advice of your medicines provider. Use medicines responsibly (