Feed additives or genomics? Can cows be made to produce less GHGs?

Methane is a far more potent greenhouse gas (GHG) than carbon dioxide, and the planet’s 1 billion cows burp their fair share of it. On the other hand, beef cows are valuable members of their ecosystems. In Canada, they spend their whole lives roaming outdoors consuming grass, crop residues and conserved hay and forages. They also provide ecosystems services, such as preventing the encroachment of invasive species on our endangered Prairie grasslands. In short, beef cows are here to stay, so we need to find a way to reduce their methane production.

At least four approaches to reducing methane and GHG emissions have been considered: feed additives, genetic/genomic selection, breeding and operational management, and adjustment of the rumen microbiome. Let’s see how the first two stack up. The Economic Times summarized the different feed additives nicely in this article.

“The DSM product works,” says John Basarab, a beef scientist with the University of Alberta and Gentec-associated researcher. “That product has a scientific basis, and is supported by studies all over the world, including by Agriculture and Agri-Food Canada researchers Karen Beauchemin and Tim McAllister.”

Lemongrass may also work (researchers at University of California Davis have an ongoing trial), possibly due to its small amounts of essential oils. However, we don’t know for sure if feeding edible oil to cattle reduces their methane emissions, but we do know that feeding more than 5% oil in the diet can lower feed intake and performance. So no panacea!

“A better candidate is seaweed,” says Basarab. “Specifically, a red seaweed from the Asparagopsis family that’s getting amazing amounts of mitigation in trials in New Zealand. They’re getting 40-98% reductions in feedlot cattle, not just in the lab.”

Of course, the study needs to be repeated to see if others can get similar results. And we still need to find out if seaweed affects meat quality, animal welfare, etc.

But here’s the real kicker with additives… The trick is to get them into cattle in a consistent and regulated dose. How do you do that when animals are way out on pasture, and can pick and choose what they eat (or don’t eat)? Some cows love the pelleted additive-containing feed and gobble it all up, leaving none for the others. So additives work best in feedlot situations where it’s easier to control feed ingredients and intake. But remember, Canadian cows are outside year-round, and feeder cattle only spend 3-5 months of their lives in feedlots, so the potential for reducing GHGs is limited. Other factors to consider are additive regulation, availability, producing to scale, cost and transportation. The Canadian Food Inspection Agency must approve any new feed ingredients, and the DSM additive has yet to be approved. Lemongrass is a tropical grass and not likely a methane-mitigating candidate for the Canadian beef industry. Seaweed can be harvested off the west and east coasts or grown though aquaponic systems—although scale up, cost and transportation will be sizable challenges. Again, no panacea!

All this sounds promising at best. What about genetics?

Improving feed efficiency through genomics will reduce GHG emissions from beef production primarily because feed-efficient cattle need less feed for the same level of production. This kind of progress is cumulative, but slow, and unlikely to match the immediate mitigation potential that feed additives, alternative management, and breeding strategies have.

“We’ve also done projects that resulted in molecular breeding values for methane emission,” says Basarab. “But again, genetic progress is expected to be slow!”

Why so slow? The dairy and pork sectors are vertically integrated, allowing them to reap the benefits of genomics (production efficiency and profitability) relatively fast. In contrast, the beef sector is fragmented, with some parts of the value chain competing against each other, and limited sharing of data for mutual benefit. Basarab estimates that reducing beef cattle’s methane emissions by 10% through genetic/genomic selection would take 20-25 years at the present rate of adoption—or 10% in half the same time if the industry integrates and adopts technologies like genomics.

“The bottom line,” he says, “is that, if we want the beef industry to lower its carbon footprint, we need a combination of strategies: operational management to reduce days to slaughter and increase carcass weight; breeding management to increase hybrid vigour; feeding management and nutrition to improve production and feed efficiency; and genetic selection and the adoption of genomic technologies to improve hard-to-measure traits and speed the rate of genetic improvement. One single way isn’t best.”

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