Lay Summary This study evaluated the effects of adding an Aspergillus oryzae-based feed additive (AO) to the diets of Angus crossbred steers fed a corn silage-based diet. The objective was to evaluate how the AO might influence enteric methane (CH4) emissions and nutrient digestibility of the animals. Steers were divided into two groups: one received AO in their diet at a rate of 0.032% of diet dry matter, while the other did not receive the feed additive. Steers were housed in pens equipped with a Vytelle system to track individual feed intake. Following a three-week adaptation period, individual enteric CH4 emissions and total tract digestibility were measured for five days. Supplemental AO had no significant effect on feed intake and tended to increase enteric CH4 emissions per kg of organic matter intake. Steers supplemented with AO showed increased nutrient digestibility. Consequently, no difference was observed in CH4 emissions per kg of organic matter digested. Though supplementation of AO improved nutrient digestion, the impact on enteric CH4 emissions was only marginal. Further research is needed to determine whether supplementing AO in cattle diets could reduce CH4 emissions per unit of animal products, such as meat or milk.
Podversich et al. (Wed,) studied this question.