Efficacy of methane-reducing supplements in beef cattle rations

The objective of the present study was to evaluate the effect of including a pellet containing feed components targeted at methane-producing microbes and methane-producing biochemical pathways, into the ration of beef cattle in southern Australia. The so-called methane-reducing supplement' (MRS) components were chosen from readily available and inexpensive sources to ensure high adoption of the practice if successful. The effect of the pellet on animal performance, diet DM digestibility and gas emissions (measured using an open-circuit gas quantification system) of beef cattle in comparison with animals fed a control diet or high-quality supplement (HQS) was evaluated. In the first trial, there were no differences in DM and digestible energy (DE) intake, but the methane emission in g/day, g/MJ of DE intake (P < 0.01), and in g/kg of DM intake (P = 0.01) were lower for steers fed MRS. There was also a trend to lower carbon dioxide emission (g/MJ of DE intake) in steers fed MRS (P = 0.07). In the second trial, heifers fed the MRS produced 18.7% less carbon dioxide (P < 0.01) and 15.5% less methane (P = 0.01) than heifers on the HQS supplement, when expressed in g per unit supplement intake on a bodyweight basis. There was no difference in growth rate of heifers on the HQS and MRS supplements. Combining methane-inhibiting feedstuffs derived from agro-industrial by-products into supplements for cattle in southern Australia appears to be an effective means of reducing methane output and methane intensity from grazing beef cattle.