Parasite control methods in organic and conventional dairy herds in Sweden

The objectives of this study were to compare methods of parasite control and to get an indication of the magnitude of parasite infections in organic and conventional dairy herds in Sweden. In February 1997, a questionnaire with mainly multiple choice alternatives was distributed to 162 organic and 162 conventional dairy farms in central Sweden. The response rates were 84% and 72%, respectively. A majority (58%) of the conventional farmers reported that their animals were treated prophylactically, mainly with controlled-release intraruminal devices. In organic production, parasite control methods involving grazing management combined with nutritional supplementation with concentrates and/or forage was the most frequently reported anti-parasite strategy. The most common procedure was to turn calves out on pastures not grazed by any cattle in the current or previous grazing seasons. This was employed by significantly more organic than conventional farms (40% vs. 3%), as was alternating grazing with other livestock species (27% vs. 3%). Sixty percent of the organic and 52% of the conventional farmers reported that they used nutritional supplementation in the autumn, and 48% and 29% of the producers, respectively, that they used nutritional supplementation in the spring, as methods to restrict parasite problems in their calves. Outbreaks of diarrhoea in first grazing season cattle and a lower weight gain during the grazing season than in the previous winter season, problems that may be due to parasite infections, were reported more frequently from organic herds. Despite an apparently increased awareness of various worm control strategies, organic farmers thus seemed to have greater problems with parasite infections than did conventional farmers.  2000 Elsevier Science B.V. All rights reserved.