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Parasol Activities in Belgium

The total cattle population in Belgium is 2.5 million, of which about 550,000 are adult dairy cows, 535,000 are beef cows, 161,000 are calves for meat production and the remainder are replacement stock. In most dairy herds and traditional beef herds, calves and cows are grazed on pasture and gastrointestinal parasites are considered of major economic importance. Many farmers rely on intensive anthelmintic treatments to prevent these economic losses in their young stock,but also more and more in the adult animals. The PARASOL activities in Belgium are conducted by P1 (Laboratory of Parasitology, Ghent University) and focus on improved diagnosis of worm infections and targeted treatments. The aim is to aided by simple diagnostic tests-target anthelmintic treatments to the herds or animal groups where worms are causing reduced productivity. This will allow built-up of natural immunity and prevent unnecessary treatments costs. In all the activities, there is a large cooperation of veterinarians and farmers, to whom we are very grateful.

Explaining the aims and strategies of PARASOL to veterinarians
In 2007, four meetings were organized throughout the country, attented by more than 100 veterinarians. On these meetings the methods and advantages of improved diagnosis and targeted deworming in cattle were explained. At the end of the meeting, discussions were held of the problems in worm control encountered by farmers and vets and how these could be addressed.

Gastrointestinal worms in first-season grazing cattle
In 2006, 271 farms were monitored for worm infections by blood pepsinogen determination at housing by 110 veterinarians. In 2007, the number of participating farms increased to 677, performed by 175 veterinarians. Based on the results of the pepsinogen test and knowledge of pasture management, advice on anthelmintic treatment strategy can be given to the farmer for the coming year. For this advice, the farmer should address his veterinarian. It is important to monitor worm infections each year. For instance, in 2007 we observed higher worm infection levels than in 2006 (Figure 1).

Fig 1. Pepsinogen results of 2006 indicating that worm exposure in firstseason grazing calves was optimal in 56% of the herds, too low in 42 % of the herds and too high in 2 % of the herds

Gastrointestinal worms in adult dairy cows
In 2006 and 2007, more than 1000 dairy herds were monitored by bulk-tank milk analysis (Figure 2). The results suggested that on approximately 30-50 % of the farms the infection levels were high enough to cause milk-yield losses. On these farms, anthelmintic control measures based on anthelmintic treatment (once at housing) or pasture management is adviced. For the interpretation of test results and decision on the best control strategy the farmer should always rely on his veterinarian.

a	b

Fig 2. Milk samples collected from the bulk-tank (a) are used to assess the level of exposure to gastrointestinal worms in adult dairy herds (b).

Monitoring efficacy of anthelmintic drugs
In several countries such as UK, New Zealand, Argentina and Brazil, resistance of worms against the currently used drugs have been reported. In Belgium, the occurrence and extent of resistance is not known. Therefore the efficacy of anthelmintic treatments is being monitored by faecal egg count reduction tests. In this test, it is investigated whether worm eggs remain present in the faeces after deworming the animals (Figure 3). In 2008, anthelmintic efficacy will be evaluated on 100 farms in Belgium.