Find in Library

<i>Urochloa</i> spp. are the most important grasses for ruminants in Brazil and contain secondary metabolites, mainly saponins. <i>Urochloa brizantha</i> extracts (ethanolic EE and hydroalcoholic HE with 3.62 and 5.38 mg protodioscin mL⁻¹, respectively) were developed to verify their potential as additives for ruminant nutrition. The in vitro gas production technique was used to evaluate ten treatments in a completely randomized factorial arrangement (2 × 4 + 2), where the main effects were two extracts (EE and HE); four levels (50, 100, 150, and 200 mL of the extract kg⁻¹ of DM), plus two controls (one positive with 25 ppm of monensin and another with no additives). The extracts EXT (EE and HE) produced a higher proportion of acetate (C2) and lower propionate (C3) than CTL, reflected in a 31% higher C2:C3 ratio. However, there was no significant difference (<i>p</i> > 0.05) between the treatments for methane production parameters. <i>Archaea</i> and <i>Ruminococcus’</i> relative gene expressions were higher in EE than in HE; however, the protozoa opposite occurred, HE was higher than EE. <i>Fibrobacter succinogenes</i> were 33% lower in EXT than in CTL. The addition of these extracts in a sheep diet increased the production of SCFA and decreased <i>Fibrobacter succinogenes</i> without altering the methane and archaeal population.