ONE OF the main reasons for the lack of thrive in young cattle at grass is due to infection by parasites. The main parasites are gut (stomach) worms, lungworms (hoose), liver fluke and rumen fluke. In young stock severe infection can reduce growth rates by up to 30pc. This will make it very difficult to achieve target weights for age for both beef animals and replacement heifers.
There are three key areas to controlling parasites in young animals.
1 Identify the risk
Young stock particularly artificially reared calves at grass for the first time are most at risk of infection as they are eating reasonable amounts of grass and have very little immunity developed. But other grazing cattle exposed to worms may also suffer production losses.
Permanent grassland grazed by livestock in the previous couple of months poses a very high risk of infection. Young animals should ideally graze, new reseeds, after silage has been cut or grass that has had no stock for greater than six months.
Worm build up on grass over the grazing season and infective stages generally peak from mid- summer onwards.
2 Treat correctly
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 of 0.7kgs 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.
Strategic use of wormers (anthelminthics)
Treatments are generally focused 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/clear drenches, avermectins or boluses. Check with your vet to establish the period of cover that you have.
3 Avoid resistance
Use products correctly, avoid under dosing animals, weigh cattle if possible to get correct weigh.
Check dosing equipment to ensure correct amount is applied. Follow the instructions on the label.
Good control can be achieved by using anthelminthics responsibly, focusing 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.