One study [1] compared two different types of grasses vs grain feed. The cows that ate grass produced more methane per kJ consumed than those that ate the grain

One study [1] compared two different types of grasses vs grain feed. The cows that ate grass produced more methane per kJ consumed than those that ate the grain feed. There are a bit stranger numbers preceding these figures, where the cows that ate one grass type actually produced less methane overall than all the other cows, but apparently because they were consuming considerably less (all cows were allowed to eat freely). Mind you, this was a study of 6 cows. [1] https://pdfs.semanticscholar.org/c726/1bccd1f76d5060913b56cc13180eefafb78b.pdf https://pdfs.semanticscholar.org/c726/1bccd1f76d5060913b56cc...