The Mechanism of Sodium Sulfate Coupled with Anaerobic Methane Oxidation Mitigating Methane Production in Beef Cattle.

The aim of this experiment is to explore the effect of sodium sulfate (NaSO) on methane reduction in the rumen, and its impact on anaerobic methane-oxidizing archaea (ANME). Using mixed rumen fluid from four Angus cattle fistulas, this study conducted an fermentation. Adding NaSO to the fermentation substrate resulted in sulfur concentrations in the substrate of 0.4%, 0.6%, 0.8%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, and 2.4%. The gas production rate and methane yield were measured using an gas production method. Subsequently, the fermentation fluid was collected to determine the fermentation parameters. The presence of ANME in the fermentation broth, as well as the relationship between the number of bacteria, archaea, sulfate reducing bacteria (SRB), ANME, and the amount of NaSO added to the substrate, were measured using qPCR. The results showed that: (1) the addition of NaSO could significantly reduce CH production and was negatively correlated with CO production; (2) ANME-1 and ANME-2c did exist in the fermentation broth; (3) the total number of archaea, SRB, ANME-1, and ANME-2c increased with the elevation of NaSO. The above results indicated that NaSO could mitigate methane production via sulfate-dependent anaerobic methane oxidation (S-DAMO) in the rumen. In the future management of beef cattle, including sodium sulfate in their diet can stimulate S-DAMO activity, thereby promoting a reduction in methane emissions.