Evaluation of the chemoprophylactic efficacy of 10% long acting injectable moxidectin against gastrointestinal nematode infections in calves in Belgium.
The chemoprophylactic efficacy of a single dose of the 10% long acting (LA) injectable formulation of moxidectin on nematode infections in calves, was evaluated. Two similar groups of 11 female, first grazing season Holstein calves were turned out in early May on separate plots of a single, naturally infected pasture. Until 56 days post-treatment (pt), the percentage reduction in faecal egg output was 100%, remaining above 90% during the entire trial, except for day 126 pt. More than 90% of the larvae in the treated group were identified as Cooperia until 140 days after treatment and more than 70% during the rest of the trial, whereas in the control group Cooperia was the most abundant species until day 84 pt and Ostertagia from 126 days pt onwards. The reduction in faecal egg output in the treated group was reflected in the mean pepsinogen levels being below the pathogenic threshold at the end of the grazing season (1.8 units of tysrosine (U tyr)) and the absence of diarrhoea during the second half of the grazing season. In the control group pepsinogen levels remained high (mean: 5.5 U tyr) and prolonged diarrhoea occurred in the second half of the grazing season. Furthermore, the weight gain for the treated group at the end of the grazing season was 41.9 kg higher than for the control group. At necropsy, the reduction in O. ostertagi worm burden in the treated group was 97.5% compared to the control group, while the reduction in C. oncophora worm burden was 57%. An additional benefit of the long acting parasitological control, was reduced pasture contamination.
Geurden
T
T
Department of Virology, Parasitology and Immunology, Ghent University, Merelbeke, Belgium. thomas.geurden@ugent.be
Claerebout
E
E
Deroover
E
E
Vercruysse
J
J
D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D001530:Belgium; D001835:Body Weight; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology*; D003967:Diarrhea / Q000469:parasitology / Q000517:prevention & control / Q000662:veterinary; D005243:Feces / Q000469:parasitology; D005260:Female; D007279:Injections, Subcutaneous; D007411:Intestinal Diseases, Parasitic / Q000517:prevention & control / Q000662:veterinary*; D018942:Macrolides / Q000627:therapeutic use*; D009348:Nematoda / Q000254:growth & development*; D009349:Nematode Infections / Q000469:parasitology / Q000517:prevention & control / Q000662:veterinary*; D010270:Parasite Egg Count / Q000662:veterinary; D006109:Poaceae / Q000469:parasitology; D011897:Random Allocation
D000871:Anthelmintics; D018942:Macrolides; C027837:moxidectin