What do cows eat? If you’re about to say “grass”, then ruminant nutritionist Fran Cowley from the University of New England will quickly set you straight.
“They chew grass,” she concedes, but the nutrients that a cow needs to grow come almost entirely from the billions of microbes that take up residence in its gut.
Cowley’s job is to tweak this roiling ecosystem so that it churns out more nutrients for the cow, and less of the potent greenhouse gas methane.
“It’s a win-win situation,” she says.
But there’s a third important beneficiary in the equation. The farmers Cowley works with – subsistence farmers in Indonesia, Cambodia and Myanmar – are some of the poorest, many earning less that $2 a day.
Fatter, healthier cows can make the difference between just scraping by and having enough money to send your children to school and pay for unexpected medical bills.
Traditionally, smallholder farmers – those who cultivate rice and other crops on small parcels of land – might own just one or two cows. These “cash cows” don’t earn the farmers a steady income, but they are useful assets that can be sold for quick cash when times are tough.
“It’s like an online savings account,” says Cowley.
Cowley works directly with farmers and local research organisations to find cheap, low-cost or no-cost feed that can turn a “savings” cow into a money-spinner.
Tree legumes, such as Leucaena, are one solution. Like soy and other legumes, Leucaena trees use nitrogen-fixing bacteria to harvest nitrogen from the soil. This allows them to plump their leaves full of protein, which makes for a high-quality cow feed that doesn’t need to be purchased and replanted each year and takes far less time to harvest than dry straw.
Leftover waste meal from cassava, palm oil, and coconut processing are also good feed options in some communities.
The aim is for cows to be healthy enough to produce one calf per cow per year, which can be fattened and sold. Additional resources are put towards buying skinny cattle and fattening them for market, too. The difference between the cows’ usual diet and a more nutritious diet is huge. Fattening times can be slashed from 18 months to just six.
Not only does this deliver money to farmers’ pockets, it drastically reduces the amount of methane the cows belch into the air. When cows are fed high-quality, protein-rich diets, the ecosystem of microbes in their rumen – which Cowley describes as a “big fermentation vat” – shifts.
Instead of being dominated by polluting methane-producers, the ecosystem becomes dominated by cow-fattening nutrient-producers. These bacteria churn out volatile fatty acids, such as propionate, which is absorbed and converted to glucose in the cow’s liver.
Now, when she travels to villages on the island of Lombok in Indonesia, Cowley sees change. More brick houses, more tractors and motorbikes, fewer bark huts than only a couple of years ago. And children who once spent hours each day gathering straw can attend school.
“To actually see the changes happening in communities is really rewarding,” she says.
Dyani Lewis is a freelance science journalist based in Melbourne, Australia.
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