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Worms in cattle: high-risk periods at pasture
Assessing and reducing pasture risk is a key element of a successful worm management plan. It can help to reduce our reliance on anthelmintics and provide quality grazing for our livestock.
Back to: Controlling, monitoring and treating worms in cattle
The risk of infection and disease varies according to the type of parasite. Generally, a disease caused by stomach and lungworms is seen in the summer and autumn.
Creating a map of your grazing platform and assigning a risk value to it, then grazing appropriately, can help you decide how you use your paddocks and reduce the risk of heavy parasite burden year-on-year.
|
High-risk |
Medium-risk |
Low-risk |
Spring |
Grazed by first-year youngstock in the previous year |
Grazed only by adult or yearling cattle the previous year (inc. cows with calves at foot) |
New leys and forage crops. Sheep or conservation only in the previous year |
From mid-July |
Grazed by untreated, first-year, weaned calves |
Grazed by adult cattle |
Ungrazed silage/hay fields or grazed by sheep, newly sown forage crops or arable by-products |
Explore how these principles can be applied to some common farming scenarios
Infection of pasture with gut worms
The survival of larvae depends largely on temperature. Survival over winter can be higher in cold conditions, particularly under snow. After three weeks, these newly acquired infections will result in an adult population of worms that start to lay eggs. These eggs deposited on pasture in spring develop slowly to the third larval stage. As temperatures increase from April to June, development time shortens, larvae develop within 3–6 weeks at temperatures of around 10°C and within one week or less when temperatures are 15 to 23°C.
Infective larvae need moisture to leave the dung and make their way onto herbage, where they are more likely to be ingested by cattle.
By mid-July, there is an abundance of larvae on the pasture.
So, while some ill-thrift can occur in the first two to three months after turnout, the risk of significant loss of weight and scouring is greatly increased from July onwards.
Useful links
Find out more about the Control Of Worms Sustainably (COWS) programme
Controlling worms and liver fluke in cattle for Better Returns manual