Evaluation of three strategic parasite control programs in captive wild ruminants

Abstract

Parasite control in wild ruminants is based mainly on anthelmintics. The objective of the present study was to evaluate three parasite control programs in seven herds of captive wild ruminants in 3 consecutive years. In the first year, a biannual spring-summer treatment regime with fenbendazole at 7.5 mg/kg body weight p.o. for 3 days was applied. The next year, an early-season treatment program with three administrations of fenbendazole at the same dosage at 3-wk intervals was used. In the third year, an early-season treatment program with ivermectin (0.2 mg/kg p.o. for 3 days), applied three times at 5-wk intervals, was evaluated. Effectiveness of these control programs was assessed by fecal egg counts and by scores of body condition and fecal consistency at weekly intervals. Involved animal species were Arabian oryx (Oryx leucoryx), scimitar-horned oryx (Oryx dammah), slender-horned gazelle (Gazella leptoceros), Soay sheep (Ovis aries soay), ibex (Capra ibex), red deer (Cervus elaphus hippelaphus), and Nelson's elk (Cervus elaphus nelsoni). With the spring-summer regime, fecal egg counts remained low during the first 5 mo, but from September onward, they slowly increased to significant levels in all seven herds. The early-season program with fenbendazole resulted in fecal egg counts near zero during the entire year in four herds but a significant egg shedding from August onward was noted in Arabian oryx, scimitar-horned oryx, and Soay sheep. The early-season program with ivermectin resulted in very low to zero egg shedding in gazelle, adult Soay sheep, ibex, red deer, and Nelson's elk during the entire grazing season, but failed to prevent high shedding in October in Arabian oryx and scimitar-horned oryx. High contamination of grassy pastures with infective larvae/eggs in the previous year or before the first treatment may explain failure of the treatment regimes in some herds.