Effects of the citrus flavonoid extract Bioflavex® or its pure components on rumen fermentation of intensively reared beef steers
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Two experiments were performed to study the effects of the citrus flavonoids extract Bioflavex® (Interquim S.A., FerrerHealthTech, Sant Cugat, Barcelona, Spain; BF) or its components on the rumen fermentation of a high concentrate diet. In an in vivo experiment, 8 Friesian steers (398 ± 12.2 kg body weight) fitted with a rumen cannula were given a basal concentrate (CTR) or CTR supplemented with BF (450 mg/kg dry matter, DM) in a 2 x 4 cross-over design. No differences were observed in performance parameters of BF and CTR steers. Diet BF increased pH values and the molar proportion of propionate. On the other hand, it reduced lactate concentration as a result of an increase in the relative abundance of lactate-consuming microorganism Selenomomas ruminantium (P < 0.01) and Megaesphaera elsdenii (P = 0.06). In an in vitro experiment, the effect of BF and its pure flavonoid components added to the incubation medium was studied separately. Bioflavex® and its main components naringine (NG), neohesperidine (NH) and poncirine (PC) were added to the incubation medium at 500 µg/g DM, with the unsupplemented substrate also included as a control (CTR). After 12 h of incubation, flavonoids mixture and NH and PC reduced (P < 0.01) the volume of gas produced and the molar proportion of acetate (P < 0.01), increased that of propionate (P < 0.01). Poncirine reduced the relative quantification of Streptococcus bovis, whereas NH and BF increased the relative quantification of M. elsdenii in relation to CTR (P < 0.01). Bioflavex® supplementation in steers in feedlot was effective in preventing collapses in pH and enhanced rumen fermentation efficiency through modifying the activity of lactate-consuming bacteria and a greater molar proportion of propionate and a reduction of that of acetate, suggesting its positive role in modulating the activity of rumen microbiota.