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In vitro acidification potential and fermentation pattern of cereal grains incubated with inoculum of ruminants given forage or concentrate based diets
This work aimed to study Tthe acidification and fermentation pattern of maize (M1, M2, M3), barley (B1, B2, B3) and sorghum (S1, S2, S3) varieties depending on the rumen environment (inoculum from forage or concentrate diets, FI or CI) were studied in 10 h incubation series, in 10 h incubation series with a low buffered medium with rumen inoculum from forage (FI) or concentrate (CI) diets. With CI, Ggas volume from barley with CI was similar to maize (P > 0.05), except at 4 and 6 h, when M2 and M1 were lower. Barley or maize Vvarieties of either barley or maize did not differ in gas production (P > 0.05). After 10 h, barley and maize produced on average 82.5 and 73.0 mL/g OM, whereas S1, S2 and S3 rendered 68.4, 31.1 and 39.7 mL/g. With FI, differences between barley and maize were detected after 6h (61.0, 35.3 and 14.1 mL/g organic matter (OM) at 10h for barley, maize and sorghum). Among inocula, pH with CI was lower than with FI (P < 0.001), final pH being 5.25 and 5.76, respectively. Incubation pH at 10 h was 5.51, 5.21 and 5.00 with CI, and 5.52, 5.85 and 5.91 with FI, for sorghum, maize and barley varieties, respectively. Average gGas production and volatile fatty acids (VFA) concentration were higher (P < 0.001) with CI than FI (67.3 vs. 36.8 mL/g and 31.0 vs. 19.9 mmol/L at 10 and 8 h). Butyrate and valerate proportions were higher with CI (P < 0.001), whereas acetate and branched chain VFA were lower (P < 0.001). The fFermentative activity against vitreous starch such as maize or sorghum wasis lower for forage than concentrate inoculum. Study of fermentation of starch-rich substrates in a low buffered medium gives a more realistic picture than conventionally buffered conditions.
AN16425 Accepted 26 July 2017
© CSIRO 2017