Submitted to: Veterinary Parasitology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/2/2006
Publication Date: 11/1/2006
Citation: Lange, K.C., Olcott, D.D., Miller, J.E., Mosjidis, J.A., Terrill, T.H., Burke, J.M., Kearney, M.T. 2006. Effect of sericea lespedeza (Lespedeza cuneata) fed as hay, on natural and experimental Haemonchus contortus infection in lambs. Veterinary Parasitology. 141:273-278. Interpretive Summary: Widespread resistance of gastrointestinal worms to chemical dewormers has led to the need for alternative parasite control. Plants containing condensed tannins, such as sericea lespedeza, may have some deworming properties, but whether preserving the forage will affect this is unknown. Sericea lespedeza hay maintained deworming activity when fed to lambs. These results indicate that sericea lespedeza hay aids in the control of internal parasites in lambs and this information is important to extension agents, scientists, and a growing number of small ruminant producers.
Technical Abstract: Condensed tannin (CT) containing plants are being investigated to find alternative solutions to the problem of nematode infection and anthelmintic resistance. This investigation was conducted to evaluate the effect of the CT-containing forage sericea lespedeza (SL), fed as hay, on a predominant Haemonchus contortus infection in sheep. Twenty-four naturally infected lambs were removed from pasture and maintained in cement-floored pens. Lambs were randomly divided into 4 groups (6 animals each): Two groups remained naturally infected, and 2 groups were dewormed to remove infection. The dewormed groups were then given an experimental trickle infection. For both natural (Study 1) and experimental (Study 2) infections, one group was fed SL hay and the other group was fed bermudagrass hay. SL hay feeding was stopped after 7 weeks and 3 animals from each group were necropsied at 9 weeks to determine effect on worm number. SL effect on worm egg output (fecundity) was determined by weekly measurements of fecal egg count (FEC) and blood packed cell volume (PCV). For Study 1, SL hay effectively reduced FEC during the time of feeding and subsequently FEC increased after feeding stopped. Similarly in Study 2, SL hay effectively prevented FEC increase until feeding was stopped. Percent reduction in FEC for both studies ranged from 67 to 98% during the SL feeding period and dropped substantially to 31 to 53% after feeding stopped. Worm counts indicated that SL hay effectively reduced established worm populations but had little or no effect on the establishment of incoming larvae. In Study 1, PCV supported removal of worms, but not in Study 2. SL fed as hay may be useful to remove existing worms but not establishing worms, and the decrease in fecundity could result in reduced pasture contamination.