Philippine E-Journals

Use of a Larval Development Assay to Estimate Anthelmintic Efficacy in Goats in Smallholder Farming Systems

Virginia M. Venturina | Patricio B. Ancheta | Salcedo L. Eduardo | Robert J. Dobson | Douglas Gray

Discipline: Agribusiness

 

Abstract:

Resistance to benzimidazole anthelmintics was demonstrated in nematodes isolated from feces of goats from 30 farms in the province of Nueva Ecija, Philippines. The average efficacy was 84% (range: 7-100%). The method used to detect resistance was a larval development assay modified from a commercial product, Drenchritea. Feces were collected per rectum or from the ground after herding groups of goats in a yard or in a shed with slatted floor. A questionnaire survey of goat owners produced information on herd size, management practices and deworming procedures. The range of farm sizes was 3 to 72 goats and larger farms tended to have lower levels of efficacy. No other management or deworming factors were significantly associated with efficacy as measured by the larval development assay. Haemonchus and Trichostrongylus were the most numerous genera present in the fecal samples and Haemonchus tended to be present in higher numbers among the resistant larvae found on the assay plates. These findings confirm earlier reports of resistance of nematodes to benzimidazole dewormers in goats and sheep in the Philippines. It also established larval development assays as appropriate for use in surveys among small farms where drench trials are not possible. Moreover, it indicates that a more extensive study of the factors associated with resistance may provide information to develop strategies to prevent its spread among smallholder farming communities.