Parasitecontroliskey

With the increased rainfall and the deterioration in ground conditions over the last few weeks, turning out stock might have slipped a notch on the to-do list; however, we should still be focused on trying to get stock out to grass at every opportunity that allows.

With this in mind, looking at controlling parasites at and post turnout should also be given careful consideration to ensure we can achieve our maximum daily gains outdoors.

Cattle acquire parasite infections while grazing pastures. This means that turnout is the beginning of the period when animals are exposed to the infective stages of parasites on the pasture.

If cattle become infected it may be several weeks before signs of parasitism are seen. These signs include reduced growth rates, scouring, coughing and reduced fertility.

To reduce losses due to poor performance, it is better to implement a parasite control programme before noticeable clinical signs are seen.

While it is tempting to treat frequently to counteract any production losses, there is an increased risk of resistance in the long-term if anthelmintics (wormers) are used incorrectly or over-used. Farmers should work closely with their veterinary practitioner to develop the most suitable parasite control programme specific for their farm conditions.

If you suspect that there may be resistance on your farm, consult with your veterinary practitioner as this can be tested by taking faecal samples before and after treatment.

To maximise the effectiveness of anthelmintics, ensure that the correct dose is being given according to the weight of the animals.

Controlling gut worms depends on effective grazing management, good nutrition, and the appropriate use of anthelmintics. Control involves trying to limit the typical increase in parasite contamination on the pastures that is seen as the grazing season progresses.

Animals that are high risk of being affected by worm infestation such as young calves and yearlings should be grazed on low contamination pastures. These include new or reseeded pastures, pastures not grazed by cattle the previous year, pastures previously grazed by sheep only for 1-2 months, pastures cograzed by sheep and cattle, and pastures that undergo rotational grazing.

There should be an appropriate use of anthelmintics as cattle have differing susceptibility to worms depending on their acquired immunity. Adults are at low risk of showing any clinical signs of gut worm infestations. Suckler cows usually do not require treatment for gut worms.

Animals that were not fully exposed in their first year are at higher risk e.g. late-born summer or autumn calves, and these should be monitored.

Beef suckler calves are initially at low risk of gut worm infestations as they have a low grass intake when they are still suckling from their mothers. Around weaning, beef suckler calves become exposed to contaminated pastures and are at much higher risk and should be appropriately monitored.

Dairy calves in calf to beef systems are at high risk as they are exposed to infection as soon as they are turned out. They should be grazed on a low contamination pasture and closely monitored. Calf growth rate and body condition score should be monitored.

Lungworm infection (‘ hoose’) can cause clinical signs such as coughing and difficulty in breathing. Cattle which are affected by lungworms are also more likely to develop viral and bacterial pneumonia. Cattle do develop immunity to lungworm infection, but it is short lived (6 months) and without further infection they can lose their immunity.

At the start of the grazing season, cattle are usually susceptible to new infections of lungworm but the highest challenge period is in late summer and autumn. Calves turned out onto pastures that were grazed by young animals the previous year are at higher risk of infection. Dairy-to-beef calves are at particularly high risk.

Calves should be closely monitored for early signs of respiratory disease, such as coughing and if these develop, the whole group should be treated as soon as possible. This limits the severity of the disease and contamination of the pastures. If adult cattle with partial immunity to lungworm are exposed to a high challenge, for example pastures that were previously grazed by calves, they can develop severe coughing or a drop off in milk produced (reinfection syndrome).

Ensure you know what parasites your stock have been treated for over the winter period in order that you can monitor stock and have a herd health plan in place for the coming spring and summer period.