Cow gut DNA study finds bacteria that could increase milk yields

Researchers from Scotland’s Rural College (SRUC), the University of Edinburgh’s Roslin Institute and the Rowett Institute at the University of Aberdeen analysed the rumen contents of hundreds of cows and discovered thousands of bacteria, as well as single-celled organisms called archaea.

The discovery of thousands of bacteria in a cow’s rumen, the first of its four stomachs, could improve meat and dairy production. Photo: Henk Riswick

According to SRUC, ruminants convert human-inedible, low-value plant biomass into products of high nutritional value, such as meat and dairy products. The microscopic organisms provide cattle with nutrients and energy, contribute to the animals’ health and, as a bi-product, release methane, which is a concern for global warming.

Latest DNA technologies

The latest research follows on from a study by the same team in 2018 in which DNA data from 42 cows was analysed. Until this study, the diverse mix of bacteria and archaea that live in the rumen was poorly understood and scientists were unable to link DNA analysis to food digestion, animal health and greenhouse gas emissions.

SRUC said that in their study, the team used the latest DNA technologies, including a handheld sequencing device that can quickly generate DNA data that is incredibly long and detailed. This allowed the researchers to completely sequence the genomes, from beginning to end, of several new bacterial species.

Novel genomes

They studied samples from 283 cows, identified almost 5,000 new strains of microbe and more than 2,000 novel species – microbes that previously no-one knew existed, said SRUC. Hundreds of thousands of novel enzymes, whose instructions are encoded in the DNA, may have potential uses as biofuels, or in the biotechnology industries. By analysing their genetic information, the team pinpointed previously unknown enzymes that can extract energy and nutrition from plant material.

Rainer Roehe, Professor of Animal Genetics and Microbiome at SRUC, said: “We’ve identified some 5,000 novel genomes of microbial species in the rumen that all play a vital role. Not only do they enhance breeding and nutrition to reduce greenhouse gas emissions from cattle, they also improve production efficiency, product quality and animal health.”

A gift that keeps on giving

Professor Mick Watson, Head of Genetics and Genomics at The Roslin Institute, said: “The cow rumen is a gift that keeps on giving. We were surprised by how many completely new microbes we have discovered, which is far more than in our previous study. The findings will inform studies of cow health and meat and dairy production for many years to come.”