EFFECTS OF NOVEL POLYETHER IONOPHORE HAINANMYCIN ON NUTRIENT DIGESTION, METABOLISM AND RUMINAL CHARACTERISTICS OF GOATS

Five castrated male goats (average BW 21.3 kg) with cannulae in the ru men and proximal duodenum were used to study the influence of intrarum inal infusion of the polyether ionophore, hainanmycin (0.05 mg kg(-1) BW day(-1)), on rumen characteristics and total tract digestion. Infus ed hainanmycin did not affect total volatile fatty acid (VFA) concentr ations in the rumen, but increased (P<0.05) the molar proportions of p ropionate from 21.8 to 26.3% and decreased (P<0.05) that of acetate fr om 72.8 to 68.8%. The ratio of acetate to propionate significantly dec lined (P<0.01) in the experimental period. Ruminal and duodenal chyme ammonia N (NH3-N) levels were reduced (P<0.05) 39.5 and 16.0%, respect ively, and the chyme urea-N concentration was reduced (P<0.05) 56.8% c ompared to the control. Infusion of hainanmycin had no effect (P>0.05) on apparent digestibility of dry matter (DM), organic matter (OM) or acid detergent fibre (ADF) in comparison with the control, but apparen t nitrogen (N) digestibility was markedly increased (P<0.05) from 46.1 to 56.4% in the hainanmycin infused period.