The effect of short-term consumption of a forage containing condensed tannins on gastro-intestinal nematode parasite infections in grazing wether goats

Some laboratory and small scale research has indicated that plants containing tannins may reduce hatching and development of internal parasite eggs. Tannins appeared to kill one species of worm in sheep. The present investigation was a short, preliminary study of the effect of sericea lespedeza, a common forage plant in Oklahoma that contains tannin, on internal parasites in goats. Wether goats with fecal egg counts greater than 1,200 eggs/gram (wormy animals) were used in this study. Fecal egg counts were taken at the beginning of the study and at 5, 10, and 15 days of each period. One group of six wethers grazed crabgrass/ryegrass and one group grazed sericea lespedeza (height maintained at 7-9 inches). After 15 days (first period) the groups were switched to the other forage and data were collected again. The major species of worm was the barber pole worm (Haemonchus contortus). During both periods, fecal egg counts on lespedeza started to decreased in only 5 days and by 10 and 15 days were significantly lower than for wethers grazing the sericea lespedeza pasture. Fecal egg counts increased in both periods for animals grazing the crabgrass/ryegrass. Fecal egg counts averaged 2,500 per gram for the crabgrass/ryegrass pasture and 700 eggs/gram for sericea lespedeza. Total daily production of fecal eggs was reduced from 1,730,000 to 450,000 eggs/day (a 74% reduction) by sericea lespedeza. In addition, the percentage of eggs in feces developing to L-3 infective larvae decreased from 99 to 58%. Sericea lespedeza helped to reduce pasture contamination by eggs and larvae and has potential to help control internal parasites of goats.