Rumen fermentation and liveweight gain in beef cattle treated with monensin and grazing lush forage

摘要: Objective  To determine the prevalence of subacute rumen acidosis (SARA) in beef cattle grazing lush pasture and effect monensin on reducing SARA improving animal performance. Design  Commercial Angus Murray Grey steers received a slow-release capsule (n = 19) or remained untreated 19). Cattle grazed an oats crop tetraploid ryegrass for total 91 days. Rumen fluid pH, volatile fatty acids (VFA) lactic acid concentrations body weight data were collected prior to treatment again 28, 56 days after treatment. Changes measures over time analysed using mixed model repeated analysis. Differences average daily gain between groups determined. Results  The was low during study, with only one satisfying criteria at point. treated capsules 11.9 kg heavier completion study compared controls (414.5 ± 3.88 kg vs 402.6 4.03 kg, P 0.04). VFA L- D-lactate levels did not differ cattle. However, ratio propionate acetate plus two times butyrate higher (P < 0.001) when monensin. Conclusions  Subacute consistently detected under conditions study. may have been due improved energy utilisation pasture, indicated by increased proportions rumen, rather than prevention SARA.