This additive is almost assuredly seaweed based. They could use the seaweed directly as a powder or extract the enzyme from it and concentrate that either way it is designed to inhibit methanogen bacteria from using the anaerobic fermentation products to produce methane which are stealing chemical energy from what the cow needs to grow. Every molecule of methane is less chemical energy for the cow to use for itself. Again cows do not make methane at all, bacteria in their stomachs do , bacteria that do not contribute to the symbiosis between the acetone bacteria and the cow.
Stupid auto correct...
*Acetogenic bacteria not acetone.