Abstract #W123

# W123
Lipid-coat protection of sodium selenite and copper sulfate from microbial fermentation impacts VFA synthesis and nitrogen metabolism in a dual-flow continuous culture system.
J. A. Arce-Cordero*1, H. F. Monteiro1, A. L. Lelis1, R. Restelatto2, L. R. Lima3, V. L. N. Brandao1, L. G. Silva1, H. Leclerc4, A. P. Faciola1, 1Department of Animal Sciences, University of Florida, Gainesville, FL, 2Department of Animal Sciences, Federal University of Parana, Curitiba, PR, Brazil, 3Department of Animal Sciences, Federal University of Mato Grosso, Cuiaba, MT, Brazil, 4Jefo, St. Hyacinthe, QC, Canada.

Antimicrobial effects of CuSO4 and Na2SeO3 have been reported in the literature. As common sources of Cu and Se for ruminants, we aimed to evaluate the effects of lipid-coat protection of CuSO4 and Na2SeO3 on microbial fermentation in a dual-flow continuous culture system. We used 8 fermenters in a 4 × 4 duplicated Latin-square design with a 2 × 2 factorial arrangement of treatments (2 mineral sources × 2 protection levels). Treatments were: 1) unprotected Cu and Se, 2) protected Cu + unprotected Se, 3) protected Se + unprotected Cu, 4) protected Cu and Se. Main effects of protection of Cu, Se, and their interaction were tested. Fermenters were fed 106 g DM/d and all diets had the same nutrient composition (16% CP, 31% NDF, 29.5% starch, 1.6 MCal ENl/kg, 18 ppm Cu, and 0.4 ppm Se). Experimental period length was 10 d (7 d of adaptation and 3 d for sample collections). Daily pooled samples of effluents were analyzed for VFA, NH3-N, soluble Cu and Se, ruminal true digestibility of nutrients, and flows (g/d) of total N, NH3-N, non-ammonia N (NAN), bacterial N, dietary N, RDP-N supply and bacterial efficiency. Kinetics of pH, VFA, and NH3-N was evaluated as repeated measures in samples collected daily at 0, 1, 2, 4, 6, and 8 h post morning feeding. Protection of Cu, Se, or their interaction did not affect pH and NH3-N kinetics. Protection of Se tended to reduce: NH3-N effluent concentration (P = 0.09), NH3-N flow (P = 0.07), and RDP-supply (P = 0.06); and tended to increase flows of: NAN (P = 0.06) and dietary N (P = 0.06). For VFA kinetics, protection of Cu reduced acetate % (P = 0.02), increased butyrate % (P = 0.04), and tended to decrease acetate:propionate (P = 0.06). Protecting both Cu and Se reduced isovalerate % (P = 0.05) and tended to reduce BCVFA % (P = 0.07). Our results suggest that lipid-coat protection of CuSO4 and Na2SeO3 might benefit ruminal fermentation through increased efficiency of VFA synthesis and N utilization, respectively.

Key Words: minerals, ruminal fermentation, selenium