Optimizing the use of duddingtonia flagrans chlamydospores against haemonchus contortus in feces of sheep

Abstract

The aim of this study was to identify the proportion of Duddintonia. flagrans chlamydospores that is needed to the achieve an optimum trapping efficacy in the presence of eggs or L3 larvae of Haemonchus contortus. Firstly, five groups of 15 coprocultures each were prepared, with increasing proportions of H. contortus eggs and chlamydospores (E:C) starting with Group I (control group) with a ratio of 1:0 and groups II to V with ratios of 1:1, 1:10, 1:100, and 1:1000, respectively. A second batch of fifty coprocultures was then prepared, with five groups of 10 coprocultures each and H. contortus infective larvae with chlamydospores, each group with increasing L:C ratios. The evaluation included a control group and four different L:C ratios similar to those of the first study (Groups VI, VII, VIII, IX and X). Larval reduction percentages were calculated to estimate trapping efficacy. A lower number of L3 larvae were harvested from cultures seeded with eggs and chlamydospores at E:C ratios of 1:10 or higher, compared to the number of larvae harvested in the control group (P<0.05). Similarly, when L3 larvae were used as bait, the reduction percentage initially increased with higher chlamydospore density, but efficacy did not continue to increase at L:C proportions beyond 1:10 (P>0.05). This study demonstrated the importance of adjusting the dose of D. flagrans chlamydospores. The optimal efficacy would be achieved with a proportion of 10 chlamydospores for each nematode egg or each infective larvae present in the faeces.