A Guide to Parasite Control at Turn-out
3. Therapeutic Management Animals are monitored until they show signs of clinical disease, such as weight loss and diarrhoea, and are then treated. This may be the only option in systems such as organic farms. There is a high risk of poor animal performance through subclinical PGE and of clinical problems if animals are not treated early enough to prevent severe diarrhoea, 2 Lungworms Clinical signs of lungworm infection (‘hoose’, Dictyocaulus viviparus ) include coughing and difficulty in breathing. Affected cattle have an increased susceptibility to viral and bacterial pneumonia. Immunity to lungworm develops quickly but is relatively short-lasting (approx. 6 months) in the absence of further infection. At the start of each grazing season, following housing, cattle may have very little or no immunity to lungworm and thus are susceptible to new infections again. The highest challenge risk periods for animals are late summer and autumn.
Monitoring animal performance is key throughout grazing for parasite control
Hoose worms in airways of a 3-yr-old cow.
Lungworm Control and Treatment An assessment of the pastures on a farm can be carried out to estimate the level of lungworm contamination and potential for future disease outbreaks. However, the unpredictable nature of the disease, the rapid development of larvae in faeces and the efficient dispersal to the swardmake lungwormcontrol through various grasslandmanagement practices challenging. Even with the adoption of grazing practices as outlined below, farmers need to remain vigilant for any clinical signs. Recommended turn out and grazing strategies include: 1. The ideal option is to turn first grazing season calves out onto pasture on which there were no cattle the previous year. 2. If the previous option is not available, then calves can be turned out onto pasture grazed by adult cattle the previous year. 3. Calves should be kept housed until they can be turned out onto pasture as one group. 4. If calf turnout is staggered, then the later calves should be turned out as one group onto another low risk pasture. A live lungworm vaccine is now available in Ireland and can provide good protection against hoose. It is recommended that the vaccination schedule is completed prior to turnout; this should be straightforward in autumn-born calves, but is problematic in conventionally managed spring-born calves. Booster vaccinations can be given to older cattle before turnout each year. Farmers are advised to discuss lungworm vaccination with their veterinary surgeon to see if it can be incorporated on their farms. Regardless of which control options are followed, it is essential that all ages of cattle are closely monitored over the grazing season and in the early housing period. Treatment of the whole group should be undertaken as soon as possible if clinical signs appear, in order to limit the impact of the infection and contamination of pastures.
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