MANAGEMENT-PRACTICES AND USE OF ANTHELMINTICS ON DAIRY-CATTLE FARMS IN THE NETHERLANDS - RESULTS OF A QUESTIONNAIRE SURVEY

In December 1996, a questionnaire about farm management and parasite c ontrol measures in calves was sent to 956 randomly chosen dairy cattle farmers in The Netherlands. Another 150 farmers in the vicinity of De venter who had vaccinated their calves in 1995 against lungworm were a pproached with the same questions. Our objective was to investigate th e consequences on worm control of the withdrawal of the lungworm vacci ne from the market for reasons of possible BSE contamination of the va ccine. Of the returned questionnaires, 411 (43%) of the 'at random' gr oup and 89 (59.3%) of the 'Deventer' group were valid. The most import ant data with regard to the farms of the 'at random' group (411) were: mean area 31.6 ha, mean number of calves 23, heifers 23 and milking c ows 53. Sheep (mean 37) were present on 18.3% of the farms. With regar d to management: 74.5% of the farmers turned the calves in their first year onto pasture, 25.5% kept them indoors. The average time on pastu re was ca. 5 months. Rotational grazing was practised on 81.4% of the farms, on 18.6% calves were set stocked. The first pasture of the calv es was mown before turn-out on 72.9% of the farms. On 48.2% of these f arms, calves were always moved to mown pastures. With regard to treatm ents: 33.8% of the farmers vaccinated their calves against lungworm in the years 1993, 1994 and 1995. Despite the withdrawal of the vaccine from the market in 1996, 7.2% of the farmers vaccinated their calves a s recommended, with two doses, and 13.1% with a single dose. At turn-o ut, 41.5% of the farmers gave the calves a preventive anthelmintic tre atment. Of these treatments, 65.9% were sustained of pulse release lon g acting devices. During the grazing season, 36.6% of the farmers trea ted their calves. After housing, 50.3% of the farmers gave a treatment . Signs of lungworm infection were noticed on 18.6% of the farms. Of t he 'Deventer' group (89 farmers), 96.6% turned the calves out. Of thes e farmers, 86.0% had used the lungworm vaccine in 1995. In 1996, 52.7% of the farmers had vaccinated the calves: 36.5% with a single dose an d 16.2% with the double dose. Of the 35 farmers who did not vaccinate in 1996, 62.9% gave a preventive treatment at turn-out. Clinical signs of lungworm infection were not observed on the 12 farms which vaccina ted the calves twice. On 11% of the farms which vaccinated once and on 14% of the farms which did not vaccinate, signs of lungworm infection were observed. It is concluded that more than 80% of Dutch dairy catt le farmers take appropriate measures to control gastrointestinal nemat ode and lungworm infections in calves in their first grazing season by grazing on aftermath, rotational grazing on mown pastures combined or not with preventive anthelmintic treatments. However, combinations of aftermath grazing and preventive treatment occurred on 30% of the far ms. This may be overprotective and may prevent sufficient build up of immunity, causing worm problems at a later age. The withdrawal of the lungworm vaccine from the market did not cause a rise in lungworm prob lems. Some farmers did vaccinate, despite the withdrawal. The majority used other preventive treatment measures, mainly the application of l ong acting boli. (C) 1998 Elsevier Science B.V.