Bonnie Vecchiarelli, second from left; Dipti Pitta, middle; and Nagaraju Indugu, right, are among the authors on a new paper examining the mechanisms by which a type of red seaweed inhibits methane emissions from dairy cows, with John Toth and Rachel Duffey, also of the University of Pennsylvania School of Veterinary Medicine. (Image: Courtesy of Dipti Pitta)
Methane is the second-largest contributor to climate warming after carbon dioxide, and so scientists have put a lot of attention toward addressing one of the top sources: methane emissions from livestock. In other words, cow burps are bad for the planet.
Farmers add various seaweeds to cow diets as a source of protein, unsaturated fats, and other health-promoting ingredients that provide immediate energy, says Dipti Pitta of the University of Pennsylvania School of Veterinary Medicine, and a 2016 study in Australia found that feeding sheep a species of red seaweed called Asparagopsis taxiformis (AT) eliminated methane emissions by 80%.
But the effects of this seaweed vary widely, and so researchers from Pitta’s Agricultural Systems and Microbial Genomics Laboratory (ASMG lab) and Pennsylvania State University undertook an assessment of how it alters the microbiome in the rumen, a compartment of a cow’s stomach. The results are published in the journal mBio.
The researchers randomly split 20 cows between four treatments: a high dose of AT;a low dose of this red seaweed; oregano, which also inhibits methane formation; and the control group. They rotated the animals among the treatments in four 28-day periods. The team found that the high dose of the seaweed inhibited methane emissions by 55% in the first two periods, but the effect appears short-lived. It gradually declined by the third and fourth periods.
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