Abstract

The effect of providing diets containing grass silage (12.8 g of DM/day) and barley grain (3.2 g of DM/day) or maize silage (12.8 g of DM/day) and lucerne hay (3.2 g of DM/day) into RUSITEC (rumen simulation technique) in which the grass or maize were uninoculated (GS, MS) or inoculated with strains Enterococcus faecium EF2/3s (GS + EF2/3s, MS + EF2/3s) or E. faecium EF26/42 (GS + EF26/42, MS + EF26/42) on rumen fermentation patterns and lipid metabolism was examined. The inoculated GS diets decreased proportion of acetate (P < 0.001) and increased the proportion of n-butyrate (P < 0.001) compared to control. The inoculated MS diets increased proportion of acetate, n-butyrate and decreased proportion of propionate, methane and ammonia nitrogen. The efficiencies of microbial protein synthesis were increased by the inoculated GS and MS diets. The concentration of cis9 trans11 C18:2 (CLA) and trans11 C18:1 (TVA) in effluent was similar during fermentation in both GS and MS diets, with the tendency of higher values of CLA and TVA in MS + EF2/3s diet. The biohydrogenation (BH) of C18:1 and C18:2 was decreased (P < 0.05) in MS + EF2/3s diet, but BH of C18:1 and C18:3 was increased (P < 0.05) in MS + EF26/42 diet, while BH of these FA in GS diets were unchanged.

Key words: Fatty acids, grass silage, maize silage, rumen fermentation, rumen simulation technique.

Abbreviation

ALA, α-linolenic acid, C18:3n-3; ADF, acid detergent fibre; BG, barley grain; BH, biohydrogenation; CP, crude protein; CLA, conjugated linoleic acids, cis9trans11 C18:2; dADF, degraded acid detergent fibre; DM, dry matter; dNDF, degraded neutral detergent fibre; E, energetic efficiency; EF2/3s, Enterococcus faecium EF2/3s;EF26/42, E. faecium EF26/42; EMS, efficiency of microbial protein synthesis; FA, fatty acids; GS, grass silage; IVDMD, in vitro dry matter digestibility; LA, linoleic acid; LAB, lactic acid bacteria; LCFA, long chain FA (> C18:0); LH, lucerne hay; MCFA, medium chain FA (C14:0 - C17:1); MS, maize silage; NDF, neutral detergent fibre; NM, N incorporated by microflora; OMF, organic matter fermented; PUFA, polyunsaturated fatty acids; SCFA, short chain fatty acids; TVA, trans vaccenic acid, trans11 C18:1.