The effects of feeding sericea lespedeza hay on growth rate of goats naturally infected with gastrointestinal nematodes.

摘要

Goat production is increasing in the United States due to high ethnic demand, but infection with gastrointestinal nematode (GIN) parasites is a major constraint to the industry. Increasing GIN resistance to chemical anthelmintics worldwide has led to the development of alternative control strategies, including use of forages containing condensed tannins (CT). An experiment was designed using infected and dewormed male kids (Kiko x Spanish, 6 mo old, 18.9 pl 3.25 kg) fed diets containing 25% concentrate and either 75% sericea lespedeza [SL; Lespedeza cuneata (Dum-Cours.) G. Don], a high CT forage (87 to 181 g of CT/kg), or 75% bermudagrass [BG; Cynodon dactylon (L.) Pers.] hay (n = 10/treatment). The kids were weighed every 14 d, and fecal and blood samples were taken weekly for fecal egg counts and packed cell volume determination, respectively. Fecal cultures were processed every 14 d to determine CT effect on larval development. At slaughter, adult GIN were collected from the abomasum and small intestines for counting and speciation. Blood samples were also analyzed for plasma urea-N, and ruminal VFA and pH were determined. The infected SL-fed kids had consistently lower (P < 0.05) fecal egg counts than the infected BG goats throughout the trial and greater (P < 0.05) packed cell volume beginning by d 77. Average daily gain was greater (P < 0.001) in kids fed SL- than BG-based diets, regardless of infection status (104.3 pl 5.0 and 75.5 pl 4.8 g/d, respectively). Total VFA and acetate concentrations were greater (P < 0.001) in the BG- than in SL-fed goats, whereas propionate levels were unaffected by diet. Acetate:propionate ratio (P = 0.01) and plasma urea-N (P = 0.03) levels were greater in BG-fed goats, whereas rumen pH was greater (P < 0.001) in the SL-fed goats. Feeding SL hay can reduce GIN infection levels and increase performance of goats compared with BG hay.