Rumen fluke infection in sheep: effect on growth and fertility, efficacy of treatments and rumen fluke species

Abstract

The aim of this study was to investigate the effect of rumen fluke infection on growth and fertility in sheep, because little is known about the subclinical effects of rumen fluke infection. Besides, the effect of oxyclozanide and closantel on adult rumen flukes was investigated and DNA research was performed on collected rumen flukes. In this research, sheep from a farm located in Utrecht, a province in the Netherlands, were used. A flock of 36 ewe lambs was used to investigate the effect on growth and a flock of 50 ewes was used to investigate the effect on fertility. Both flocks were divided into three treatment groups. Group 1 was treated with 15.3 mg/kg bw oxyclozanide, group 2 was treated with 10 mg/kg bw closantel and group 3 was the control group. The efficacy of oxyclozanide and closantel was determined by calculating the faecal egg count reduction percentage (FECR%). DNA research was performed on rumen flukes originating from 8 sheep. The rumen flukes were collected at an abattoir, located in the province Utrecht. Rumen fluke infection seemed to have no significant effect on growth and fertility. However, the sheep used in this research were possibly not infected severely enough to see the effects of rumen fluke infection. Oxyclozanide, in a dose rate of 15.3 mg/kg bw, caused a FECR of 50% in the flock of ewe lambs based on egg counts before treatment and 6 weeks after treatment and 84.9% in the flock of ewes where egg counts were made before and 2 weeks after treatment. These reductions were significant, compared with the control group. Closantel caused no significant reduction in rumen fluke eggs. The efficacy of oxyclozanide and closantel against immature rumen flukes was not investigated in this study. At the abattoir, different appearances of rumen flukes were observed. DNA research revealed that the rumen flukes of 7 sheep were 100% Calicophoron daubneyi (C. daubneyi). The rumen flukes of one sheep were 100% Paramphistomum leydeni. Furthermore, some darker rumen fluke eggs were seen. However, both the normal coloured eggs and the darker coloured eggs were C. daubneyi.