Abstract
BackgroundAnthelmintic treatment is the most common way of controlling nematode infections in ruminants. However, several countries have reported anthelmintic resistance (AR), representing a limitation for sustainable small ruminant production. The knowledge regarding worm control management represents a baseline to develop a guideline for preventing AR. The aim of the present study was therefore to improve our knowledge about the worm control practices in small ruminant flocks in Norway.MethodsA questionnaire survey regarding worm control practices was performed in small ruminant flocks in Norway. Flocks were selected from the three main areas of small ruminant farming, i.e. the coastal, inland and northern areas. A total of 825 questionnaires, comprising 587 sheep flocks (return rate of 51.3%) and 238 goat flocks (52.6%) were included.ResultsThe results indicated that visual appraisal of individual weight was the most common means of estimating the anthelmintic dose used in sheep (78.6%) and goat (85.1%) flocks. The mean yearly drenching rate in lambs and ewes were 2.5 ± 1.7 and 1.9 ± 1.1, respectively, whereas it was 1.0 (once a year) in goats. However, these figures were higher in sheep in the coastal area with a rate of 3.4 and 2.2 in lambs and ewes, respectively. Benzimidazoles were the predominant anthelmintic class used in sheep flocks (64.9% in 2007), whereas benzimidazoles and macrocyclic lactones were both equally used in dairy goat flocks. In the period of 2005-2007, 46.3% of the sheep flocks never changed the anthelmintic class. The dose and move strategy was practiced in 33.2% of the sheep flocks.ConclusionsThe present study showed that inaccurate weight calculation gives a risk of under-dosing in over 90% of the sheep and goat flocks in Norway. Taken together with a high treatment frequency in lambs, a lack of anthelmintic class rotation and the common use of a dose-and-move strategy, a real danger for development of anthelmintic resistance (AR) seems to exist in Norwegian sheep and goat flocks. This risk seems particularly high in coastal areas where high treatment frequencies in lambs were recorded.
Highlights
Anthelmintic treatment is the most common way of controlling nematode infections in ruminants
The dose and move strategy was practiced in 33.2% of the sheep flocks. 1.3 Dose-estimation In 78.6% of the sheep flocks the anthelmintic dose was determined by visual appraisal of the weight of the heaviest lamb or ewe before the start of the drenching operation
In 27.1% of the sheep flocks, the farmers never checked the accuracy of their drench guns when giving their animals an anthelmintic treatment
Summary
Anthelmintic treatment is the most common way of controlling nematode infections in ruminants. Several countries have reported anthelmintic resistance (AR), representing a limitation for sustainable small ruminant production. Anthelmintic-resistant (AR) nematodes are recognised as an important threat to the productivity and welfare of sheep in many parts of the world, including Europe [2]. In some countries of Northern Europe, resistance to benzimidazoles has been found in up to 80% of the goat flocks, even in a context of a rather limited drenching frequency [4], and resistance to two, or even all three, major classes of anthelmintics has been recorded for goats in France and for sheep in Scotland [5,6,7]. Less severe than under the tropics, drug resistance issue is in the UK considered a threat to the economical sustainability of sheep production [11]
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