Increased threat from rumen fluke
Rumen fluke (paramphistomosis) is becoming a serious animal health concern on Irish farms. I know we have all heard of liver fluke, but rumen fluke was certainly new to me.
It had been thought that rumen fluke wasn't to be of any significance in countries with a temperate climate like ours, but in the wet year of 2009 rumen fluke seemed to be present in significant numbers in dairy cows.
Under the microscope, rumen fluke looks like a worm, and it has a life cycle similar to liver fluke. It is picked up by the grazing dairy cow as immature fluke, but, once in the cow, it attaches itself to the walls of the small intestine.
It later moves to the rumen to become an egg-producing adult. In light infections, young rumen fluke migrate to the rumen within four to six weeks and normally no clinical infections occur.
However, in heavy infestations the development of the young fluke is slowed and they can stay in the small intestine for more than four months and cause severe disease associated with the destruction of the line of the small intestine. In a severe outbreak, as many as 70,000 immature rumen fluke may be present in the small intestine.
Eggs are passed from the small intestine in the manure. These eggs hatch in a wet environment and the larvae develop in snails. Once developed, the larvae leaves the snail, attaches itself to the grass plants, and, once eaten by the cow, the cycle starts all over again.
Heavy infections with rumen fluke can cause animal deaths in severe cases, but more moderate infection can cause reduced weight gains, lower milk production or just plain ill thrift. Severe diarrhoea can also be a feature.