Gut Bacteria Could Help Produce Tastier Cow’s Milk
July 3, 2019
Science – It’s not just good breeding and tasty grass that make a dairy cow a champion milk producer. It’s also the microbes that live in the animal’s gut. Now, BGU researchers and collaborators say they know which microbes lead to the best milk.
Cows and other ruminants such as goats and sheep have a special stomach called a rumen that houses millions of microbes. These organisms break down hay, grass and other hard-to-digest plant material into usable nutrients and calories. A downside is that ruminants burp and fart out 100 million tons of microbe-generated methane a year worldwide, making them the second-biggest human-related contributor of this greenhouse gas, after rice cultivation.
To see how these microbes play a role in milk quality and methane production, Prof. Itzik Mizrahi, a biologist and head of the Mizrahi Lab at Ben-Gurion University of the Negev, teamed up with John Wallace, an animal scientist at the University of Aberdeen in the United Kingdom, to characterize the microbes in several herds of cows and to see whether those microbes influence any of hundreds of traits, such as growth rate, milk quality and quantity, and methane production.
They collected microbial DNA and information about those traits from more than 1,000 cows on seven farms in the United Kingdom, Italy, Sweden, and Finland. The cows were Holsteins and Norwegian Reds—two breeds that constitute the majority of dairy livestock in Europe.
From the DNA, the team identified the microbes in each cow’s gut and compared communities to see what bacteria, protozoa, fungi, and other microbes they had in common. Then the researchers used machine learning—sophisticated computer programs that can find connections among massive amounts of disparate data—to figure out how microbes might influence particular traits.
Although each cow had a unique microbiome, half of the animals had 512 microbial species in common, the team reports in Science Advances. The analyses indicated that 39 core microbes are more powerful than genes in determining how tasty a cow’s milk is, and even how much methane it produces.