Effect of plant oils on methane emission and biohydrogenation in vitro

The aim of the present in vitro study was to investigate how diets enriched with 7% of plant oils (rapeseed, sunflower or linseed), with or without 2% additional mineral components, affect methane formation and biohydrogenation in the rumen. Oil supplementation to diets containing the mineral addition caused a non-significant suppression of daily methane release (sunflower 7%, linseed 9%). This suppressing effect of the oil was less evident (sunflower 4%, linseed 5%) when supplementing diets without mineral addition. Rapeseed oil did not affect daily methane formation. However, when the daily methane release was related to daily fermented organic matter, a significant reduction of this parameter was observed for all oil-supplemented diets with and without mineral addition. The degradation of dry matter, organic matter and neutral detergent fibre was not significantly affected by any of the oil supplementations. Independent of the mineral addition, the total level of biohydrogenation of 18 : 1, 18 : 2 and 18 : 3 was significantly highest with rapeseed and linseed oil supplementation. Total protozoa and bacteria counts were not significantly affected by the oil supplementation.