Effects of Euglena (Euglena gracilis) supplemented to diet (forage: concentrate ratios of 60:40) on the basic ruminal fermentation and methane emissions in in vitro condition

An in vitro study was conducted to investigate the effect of different concentrations of Euglena ( Euglena gracilis ) on CH 4 production, dry matter (DM) digestibility, volatile fatty acid (VFA) and ammonia N(NH 3 -N) concentration as well as on the protozoa population. The treatments considered were Euglena at concentrations of 0.0, 50, 100, 200, 400 and 1000 g/kg dry matter (DM) of the substrate (60:40 forage: concentrate ratio) incubated for 24 and 96 h using an in vitro continuous gas production and in vitro two-stage digestion procedure, respectively. The data were subjected to polynomial regression analysis. Methane emissions (ml/g DM) decreased at an increasing rate, generally with increasing concentration of Euglena but also exhibited quadratic ( P < 0.001) and cubic ( P < 0.001) effects while NH 3 -N (mg/ml) concentration increased at an increasing rate (linear P < 0.001; quadratic P = 0.001; cubic P = 0.024). Total VFA concentration (mmol/l) decreased significantly ( P < 0.001), when the substrate was totally replaced by Euglena. There was a linear ( P < 0.001) and cubic ( P = 0.047) reduction in protozoa population as the concentration of Euglena increased. In vitro DM digestibility was improved (linear P = 0.003; quadratic P = 0.04; cubic P < 0.001). These findings demonstrate that Euglena at concentration of 100 g/kg DM reduce CH 4 emissions by 9.1% and improve DM digestibility by 14.3%. However, when the concentration of Euglena increases from 100 g/kg DM, while further reducing CH 4 emissions, have negative effect on NH 3 -N concentration, protozoa population and VFA concentration.