Master of Science (MS)
Animal Science (Animal, Dairy, and Poultry Sciences)
Haemonchus contortus is one of the most threatening parasites to small ruminant production. Control has traditionally relied on the use of anthelmintics. Control has waned because the worm population has developed resistance to most of the currently available anthelmintics and alternative control measures are needed. Current consumer pressure is to reduce the use of chemicals in agricultural products, thus pushing control methods to more natural and acceptable approaches. One such approach is the feeding of condensed tannin containing forages either as fresh forage or dried products (hay, meal, pellets, etc). This study was conducted to determine the effect of a ground meal form of sericea lespedeza (SL), a forage plant high in condensed tannins, on H. contortus infection in sheep. Twenty-eight mixed sex lambs with essentially zero fecal egg count (FEC) were randomly allocated to 4 treatment groups (7 animals each). Two groups received a bolus of 5000 H. contortus infective larvae (L3) once and the infection was allowed to mature over five weeks (existing infection). The remaining two groups received trickle infections of 500 H. contortus L3 three times a week for three weeks (establishing infection). SL meal was fed over a five week period to one of the existing and one of the establishing infection groups while the other groups were fed bermudagrass hay. All groups were fed bermudagrass hay for an additional two weeks and then necropsied. FEC was significantly reduced in the existing infection SL fed group over the 5 week feeding period. Similarly, FEC was lower in the establishing infection SL fed group, but the difference was not significant. After SL feeding was terminated, FEC increased in both existing and establishing infection groups which indicated an effect on female worm fecundity. At necropsy, there were fewer worms in both SL fed groups, but the differences were not significant. This trend of fewer worm numbers suggested that there may have been an effect on reducing infection level also. These results indicate that SL meal had more of an effect on reducing FEC of existing female worm infections than establishing infections of H. contortus.
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Chafton, Leigh Ann, "The effect of a condensed tannin containing forage, sericea lespedeza on existing and challenge infections of Haemonchus contortus in sheep" (2006). LSU Master's Theses. 1255.
James E. Miller