Effect of Birdsfoot Trefoil on Exsheathment of Haemonchus contortus in Rumen Fistulated Sheep

Abstract

This study has been developed to address the issue of small ruminant parasite resistance to commercial anthelmintics and to examine the possibility of controlling these parasites using feeds with condensed tannin containing plants. The goal of the research was to determine whether birdsfoot trefoil hay prevents the exsheathment of Haemonchus contortus and whether efficacy differs among birdsfoot trefoil cultivars. During the first phase of research, a method for testing the exsheathment of H. contortus in vivo was developed. Various larvae containment capsules were tested to see whether the larvae could escape from the capsules. The most successful capsules were then tested in the rumens of fistulated ewes. Larvae were placed in capsules and suspended in the rumens by cords of various lengths for several different amounts of time. Using the methods developed, it was found that after eight hours in the rumen 82 ± 1% of the larvae were exsheathed. For the second phase of the research, four rumen fistulated ewes were fed diets of birdsfoot trefoil or a control. Three cultivars of birdsfoot trefoil were fed: Pardee, Empire, and Bruce. These diets were fed to the each of the ewes for 28 days in a Latin 4x4 design. During exsheathment tests, capsules containing third-stage H. contortus larvae were placed in the ewes' rumens for 8 hours. They were then examined under a microscope for any changes in exsheathment or motility. It was found that for all three cultivars, feeding birdsfoot trefoil hay did not affect exsheathment percentages. These results indicate that while further studies should be conducted to confirm these results, research on effectively incorporating condensed tannin containing plants should focus on other life stages of the H. contortus parasite.