Addressing sustainable ruminal methane and carbon dioxide emissions of soybean hulls by organic acid salts

The current study aimed to study the sustainable mitigation of methane (CH4) and carbon dioxide (CO2) emissions as well as ruminal fermentation kinetics by replacing dietary corn grain (CG) with soybean hulls (SH) in the presence of organic acid salts (OAS). Three total mixed rations were prepared where CG was replaced with SH at three levels (/kg DM): 0 g (Control), 75 g (SH75) or 150 g (SH150). The OAS was used at three levels (dose): 0, 5 and 10 mg/g DM of substrates. Increasing SH level increased (P < 0.05) the fractional rate of gas production (GP) and lag time. The SH75 and SH150 rations quadratically decreased (P < 0.001) the asymptotic CO2 production and the lag time of CO2 production. Moreover, the high level of OAS quadratically decreased (P ≤ 0.05) CO2 production. The OAS inclusion increased (P < 0.05) CH4 production (expressed as mL/g incubated DM and mL/g degraded DM). Increasing SH in the rations increased (P < 0.05) proportional CH4 production. Inclusion of OAS also increased proportional CH4 production. Replacing corn grain with soybean hulls could be a valuable means of sustainable mitigation of CH4 and CO2 emissions and improvement of the environmental conditions as well as provision of good feedstuff for ruminant livestock due to its in vitro fermentation characteristics. The organic acid salts did not affect ruminal gas production but decreased CO2 emissions; thus its supplementation when soybean hulls replace corn grain is perhaps redundant, though may be considered as environmental friendly way of feeding livestock.