With the Fourth of July holiday weekend here at last and all those barbies fired up, converting carbon into carbon dioxide while we cook our burgers, we will temporally forget about the carbon footprint. While contemplating the downside consequences of digging into the beans on the side of your plate, you’ll remember that even the uncooked burger has a big C-footprint from the gaseous eruptions of the cow it came from.
Now, cow-burps are not to be taken lightly. The UN Food & Agriculture Organization reckon that our livestock is responsible for 37% of the world’s methane emission and 9% of its carbon dioxide. I’m just glad that cows don’t drive cars and that milking parlors are no smoking zones.
Well brought up cows eat grass. The microbes in their stomachs are working their socks off to break down the cellulose into sugar so that the happy cows can skip around their meadow. Those hard-working primitive little single celled creatures give off the methane. However, all ruminants aren’t the same. Morrison has been leading a large international team to see why the kangaroo family is methane free (1).
Tammar wallabies were the focus for a burpless ruminant study. They are a handy little pocket variety being less than 18 inches tall and are a favorite in the lab. We don’t know when they went methane free, or if it was because of the hot summer fire hazards in Australia, but they have their own brand of pre-digestion bacteria which are non-gas producers. Until the work of Morrison et al, it was a closely guarded secret, but now all is revealed. The name of the resident in the secret sauce is member of the Succinivibrionacae family. As its name implies, this bacteria family produce succinates as their waste product, not methane, and are thus gas-free.
The blue skies suggestion is that perhaps we could train cows to use these instead of their existing gut population to break down the grass. There might be a fair bit of genetic engineering required but I was glad that there was no suggestion of crossing the hosts. The idea of cows hopping around the fields or of milking kangaroos for a living was way outside my imagination paygrade.
Science DOI: 10.1126/science.1205760
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