EFFICACY OF MOXIDECTIN AGAINST GASTROINTESTINAL NEMATODE INFECTIONS IN SHEEP

The efficacy of moxidectin against gastrointestinal nematode infection s was studied in 30 Fleischschaf X Rasa Aragonesa male lambs aged 3 mo nths at the beginning of the experiment. The lambs were distributed in three groups of 10 animals each and experimentally infected with a mi xture of an equal number of infective (L3) larvae from each of the fol lowing species: Haemonchus contortus (2000), Ostertagia circumcincta ( 2000), Trichostrongylus colubriformis (2000) and Trichostrongylus vitr inus (2000). Two groups of lambs were drenched with 0.2 mg moxidectin per kg body weight at 6 (Group B) and 21 (Group C) days post challenge while the third group of animals (Group A) remained untreated. The ef ficacy of the treatment based on worm counts 4 weeks post infection wa s of 100% against 4th stage larvae of all species and 100%, 99.98%, 10 0% and 100% against adults of H. contortus, 0. circumcincta, T. colubr iformis and T vitrinus, respectively. Significant differences were fou nd in daily weight gain between treated (Group B+C, 157.9 g day-1) and untreated lambs (Group A, 116 g day-1). No differences in feeding beh aviour or health condition between treated and untreated lambs were ob served.