Grassland Science, 2024 (SCI-Expanded)
The purpose of the current experiment was to determine the effects of ruminal fermentation parameters of the additions of canola or soybean oils at different rates (4, 8 and 12%) to beef cattle total mix rations (TMR), based on corn silage and barley grain. The addition of 4% soybean oil to TMR positively affected in vitro gas production, net energy lactation (NEL), metabolic energy (ME), and organic matter digestion (OMd). The additions of 8% and 12% of soybean oil to TMR linearly decreased ME, NEL and OMd (p < 0.05). The additions of 4, 8 and 12% canola oil to the TMR linearly decreased the in vitro gas production and estimated fermentation values (ME, NEL and OMd) (p < 0.05). All doses of soybean or canola oils in TMR reduced the molarities of total short-chain fatty acids (tSFCA), acetic (AA), butyric (BA), propionic (PA), valeric (VA), iso-valeric (IVA) and iso-butyric acids (IBA) for in vitro fermentation fluid (p < 0.05). There was a negative correlation between the increasing dietary stearic, oleic and linoleic acid and the end-products of in vitro rumen fermentation. However, increasing dietary α-linolenic acids had no adverse effect on in vitro ruminal fermentation end-products. As a result, 4% addition of the soybean oil, which included a higher rate of α-linolenic acid and saturated fatty acids and a lower rate of oleic, linoleic acids according to those of canola oil, to the TMR positively affected in vitro ruminal fermentation. In addition, the ≥8% addition of canola or soybean oil adversely affected the in vitro fermentation values.