Use of a citrus flavonoids extract (Bioflavex®) to improve rumen fermentation efficiency and performance in steers consuming high concentrate diets

Abstract Text: To study the effects of a citrus flavonoids extract (Bioflavex^®; BF) on fermentation and performance in steers fed high concentrate diets (90:10 Concentrate:Barley straw), two experiments were performed. In the first one, eight Friesian bulls (398±12.2 kg BW) fitted with rumen cannula and were housed in individual pens and assigned to one of two treatments, they received the basal concentrate (CTR) or the basal concentrate supplemented with Bioflavex^® (450 mg/kg DM) in 2×4 cross over design. The trial lasted for 24 days and was divided in 2 experimental periods of 12 days, 10 days for dietary changeover followed by two sampling days. In the second experiment, 32 Friesian steers (395±10.1 kg BW) were weighed and blocked in 2 homogeneous groups (BW basis) receiving the same treatments as Exp. 1 (CTR and BF) and were weighed at day 7 and 24 of the experiment. Concentrate and barley straw were offered ad libitum, once a day (0800 h) for 24 days. At the sampling days of 1^st trial, rumen was sampled (at 0, 4 and 8 h post feeding) for pH, NH₃-N, volatile fatty acids (VFAs) and microbiota analyses. BF in the concentrate improved pH values (6.1 vs. 5.8 for BF and CTR; SEM 0.05; P<0.01) and molar proportion of propionate (24. 2 vs. 22.5 SEM 0.60; P=0.05). Flavonoids did not alter absolute abundances of total bacteria nor relative abundance of Streptococcus bovis while relative abundances of Selenomonas ruminantium (P<0.01) and Megaesphera elsdenii (P= 0.05) were enhanced by the presence of BF in the concentrate. In the second trial no differences were observed neither in the final BW (425 vs. 420 kg SEM 10.9) nor in average daily gain (1.1 vs. 1.2 Kg/d SEM 0.14, for CTR and BF respectively) but feed conversion ratio was lower in BF than CTR steers (6.1 vs.6.8 SEM 0.8; P=0.05). Flavonoid supplementation might be effective in improving rumen fermentation and animal’s performance which may be explained changes induced by BF in the microbial flora.

Keywords: Animal’s performance, Flavonoids and Ruminal fermentation