INDIVIDUAL FLUCTUATIONS IN EFFICACY OF FEBANTEL AGAINST MUELLERIUS-CAPILLARIS IN GOATS

One hundred and eighty-seven dairy goats originating from 7 farms in w estern France were treated individually with febantel (probenzimidazol e drug) at a dose rate of 5 mg/kg in spring 1991. Individual faecal sa mples were collected on d 0, 7 and 21 post-treatment and processed for counting first stage larvae of Muellerius capillaris (LPG: larvae per gram of faeces). Eggs of digestive tract strongles were also counted on d 0 and 7 (EPG: eggs per gram of faeces). Blood samples were taken on d 0 to assess pepsinogen concentration related to abomasal damage c aused by strongyle infection. The individual characteristics of the go ats were recorded. The procedure was repeated on the same animals in a utumn 1991. The faecal larval count reduction (FLCR) was mainly relate d to farm and season: farm 1 in the spring and farm 6 in the autumn sh owed a higher proportion of high responder (HR) goats (FLCR > 80%), wh ereas farm 3 exhibited a lower proportion of HR goats in the autumn. O n the other hand, the characteristics of the goats (breed, physiologic al status, age, weight, presence or absence of wattles and horns) as w ell as the initial level of parasitism (LPG, EPG and pepsinogen concen tration) all had a role which was limited or zero on the variability o f response to treatment. Goats could not be individually categorized a ccording to their response level because the FLCR values obtained in t he spring were not repeated in the autumn, suggesting that other envir onmental parameters could be involved.