[Effect of a single injection of doramectin on gastrointestinal nematode infections of sheep grazing on alpine pastures].
The persistent effect of doramectin injectable against gastrointestinal nematodes was investigated in a controlled field study with 70 sheep kept on alpine pastures in Switzerland. After grazing on home pastures for four weeks 50 lambs and 20 ewes were allocated to two equal groups according to age and body weight. At turnout to alpine pasture in June doramectin (0.3 mg/kg) was administered by intramuscular injection to 25 lambs and 10 ewes (Group D), whereas control sheep (Group K) remained untreated. Animals of both groups were kept on separate pastures (altitude: 1100 m) and were rotated between three paddocks during a total grazing period of 13 weeks. After doramectin treatment faecal examinations of Group D sheep showed a marked reduction of the trichostrongyle egg output which remained close to zero for eight weeks. During this period serum pepsinogen levels did not indicate the presence of a substantial immature worm burden in the abomasal mucosa. In the last five weeks of the alpine grazing period the trichostrongyle egg counts increased markedly in the lambs of Group D. Lambs of the control group developed moderate-to-high Haemonchus-infections, and eight animals of this group had to be treated with anthelmintics. Lambs of Group D had gained significantly (P < 0.05) more weight eight weeks after turnout whereas the mean bodyweight stagnated during the last five weeks of the grazing period. The results indicate, that the single administration of 0.3 mg/kg doramectin to lambs and ewes provided good protection against severe infections with gastrointestinal nematodes for a period of approximately eight weeks.
Hertzberg
H
H
Institut für Parasitologie, Universität Zürich, Winterthurerstrasse 266a, 8057 Zürich. hubertus.hertzberg@vetparas.unizh.ch
Meyer
A
A
Kohler
L
L
Falconi
F
F
Ochs
H
H
D000818:Animals; D000871:Anthelmintics / Q000008:administration & dosage*; D005243:Feces / Q000469:parasitology; D005260:Female; D007273:Injections, Intramuscular / Q000662:veterinary; D007411:Intestinal Diseases, Parasitic / Q000188:drug therapy / Q000662:veterinary*; D007559:Ivermectin / Q000008:administration & dosage* / Q000031:analogs & derivatives; D008297:Male; D009349:Nematode Infections / Q000188:drug therapy / Q000662:veterinary*; D010270:Parasite Egg Count / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000188:drug therapy* / Q000469:parasitology; D013997:Time Factors
D000871:Anthelmintics; D007559:Ivermectin; C084101:doramectin