Efficacy of a levamisole bolus in field infections of bovine nematodes.
Forty four parasite free calves were divided into eight groups, four of six and four of five calves. Two of the groups of six were given a bolus containing 22 g of levamisole in a formulation designed to release the anthelmintic for ninety days. One group of treated calves was put out to graze at the beginning of May with one of the untreated larger groups on a field contaminated with O ostertagi and C oncophora, and the other treated group grazed with controls on a field known to have the same species plus D viviparus. On mid August these resident calves were removed, slaughtered and worm counts estimated. At the same time, the other groups of untreated calves were put onto the same fields to act as tracers of the level of infection. After grazing for one month they were housed, slaughtered and worm counts carried out. The faecal egg counts of treated calves were much less than those of the controls until the end of July. Control calves on the paddock infected with lungworm were severely affected by parasitic bronchitis whereas treated calves although infected did not display clinical symptoms. In the resident calves, O ostertagi burdens were reduced by 65 and 67% and C oncophora by 97% compared to untreated controls. In the tracer calves, there was no difference in burdens of O ostertagi and D viviparus but large differences in the number of C oncophora established.(ABSTRACT TRUNCATED AT 250 WORDS)
Taylor
S M
SM
Veterinary Research Laboratories, Belfast, Northern Ireland.
Mallon
T
T
Green
W P
WP
D000284:Administration, Oral; D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy* / Q000469:parasitology; D003692:Delayed-Action Preparations; D004022:Dictyocaulus Infections / Q000188:drug therapy; D005243:Feces / Q000469:parasitology; D007411:Intestinal Diseases, Parasitic / Q000188:drug therapy / Q000662:veterinary; D007978:Levamisole / Q000008:administration & dosage / Q000627:therapeutic use*; D008174:Lung Diseases, Parasitic / Q000188:drug therapy / Q000662:veterinary; D009349:Nematode Infections / Q000188:drug therapy / Q000662:veterinary*; D010029:Ostertagiasis / Q000188:drug therapy / Q000662:veterinary; D010270:Parasite Egg Count / Q000662:veterinary
D003692:Delayed-Action Preparations; D007978:Levamisole