Permanent grassland grazed by livestock in the previous couple of months poses a very high risk of infection.
In an ideal world, young animals should graze new reseeds, after grass where silage has been cut or grass that has had no stock for greater than six months.
These options are not always possible so you need to work with what is available.
A high stocking rate of young calves produces high pasture contamination. Worm build up on grass over the grazing season and infective stages generally peak from mid- summer onwards.
Monitoring of animals is a critical strategy that can be used.
Regular weighing to monitor average daily gains and growth rates is vital. Ideally use a scales but alternatives such as weight bands can be used as a guideline.
A weight gain for calves of 0.7 kgs plus per day indicates a very low risk from parasites. Undertake to regularly dung sample to determine the number of worm eggs present. Talk to your vet or local veterinary laboratory on this method.
If there are sheep on the farm, mixed grazing of cattle and sheep or alternative yearly grazing's with cattle and sheep can give a dilution effect of the worms present.
Use a leader follower system where the calves graze the paddock first and are followed by larger cattle, thereby reducing the risk of the older cattle infecting the younger calves.
Don't force the calves to graze the paddocks out too tight, keep the paddock size small, so that they are not in them for too long, introduce them to covers of seven to eight centimetres high grass and remove them after three days, letting in bigger cattle to clean out the paddocks.
Strategic use of wormers (anthelminthics)
Treatments are generally focussed on young stock to provide cover for the first couple of months at grass to minimise pasture contamination. Different product types have different lengths of suppression depending on whether you are using white drenches, yellow drenches, avermectins or boluses.
Check with your vet to establish the period of cover that you have.
Use products correctly, avoid under dosing animals, weigh cattle if possible to get correct weight. Check dosing equipment to ensure correct amount is applied. Follow the labels instructions.
Good control can be achieved by using anthelminthics responsibly, focussing on treating individuals or groups at appropriate times and recognising that animals can thrive without frequent treatments.
In all cases it is advisable to discuss a control strategy with your own vet as no two farms are the same.
Gordon Peppard is programme advisor for the Teagasc Calf to Beef Programme