The weather continues to remain colder than average, with rainfall dampening the expectations of better weather in the spring. The June Parasite Forecast from NADIS describes specific issues to be aware of this month.
Nematodirus remains an issue for sheep farms across the country, the weather providing the perfect environment for late hatching of parasites. As the weather begins to warm up entering June, this will contribute to a midsummer peak in pasture larval numbers.
There is a high risk of Nematodirus disease for lambs this spring. However, the risk should be assessed on a farm-by-farm basis, with veterinary advice on treatment options.
Fiona MacGillivray from Merial Animal Health, which supports the Parasite Forecast said: "For lambs grazing higher risk pastures, further prophylactic treatments can be administered. Depending on the extent of the risk, this can be done either early or late June."
In previous years a wet June and July have been associated with increased risk of parasitic gastroenteritis in sheep. Continued wet weather will tend to increase larval numbers and pasture infectivity.
As far as cattle nematodes are concerned, as the weather warms up and given that there is sufficient moisture, eggs passed by the calves will develop increasingly rapidly, contributing to the midsummer peak in pasture larval numbers. However, dry weather may reduce the availability of these larvae and delay peak infectivity.
Spring-born suckled calves will not be building up the pasture infection in this way, so most overwintered larvae will die off by midsummer, leading to a low risk of summer (type 1) ostertagiosis in these animals.
Lungworm disease may start to appear from June onwards in both calves and adult cattle, which can also be affected by this disease.
Any wetter weather conditions can favour the spread of the parasite, although across the country the recent wet summers have not been associated with an increased annual incidence.
Vigilance is key as this disease is unpredictable and can quickly have devastating effects in the herd.
Fiona says: "As a result of the wet weather at the end of last year, the risk of liver fluke infection continues to be high, and wet conditions during June will potentially support large fluke and snail populations. A strategic flukicide treatment given to cattle at grass 8 – 10 weeks after turnout will help to break the fluke life-cycle by minimising pasture contamination with fluke eggs, with a reduction in risk of winter disease. Sheep may also require strategic treatments in the spring and summer months to help minimise the risk of autumn and winter disease."
