Researchers look to omega-3 fatty acids to reduce methane emissions and make healthier milk.
By Susan Harlow
Dairy cow nutrition was once a matter of feeding for higher milk yield and cow health. But recently, feed management has taken on wider significance, as we learn more about how it affects the environment and human health. A cow’s diet ends up both in the environment and in the milk bottle, one way or another.
Stonyfield Farm of Londonderry, N.H., long concerned about its environmental impact, has for the last decade sought to reduce the carbon footprint of milk production – its largest contributor of greenhouse gases. The toughest part has been dealing with enteric emissions, or the methane from a cow’s digestion. So when Stonyfield learned how Group Danone, the French company which holds a large share in Stonyfield, uses dairy nutrition to reduce its greenhouse emissions, the U.S. company began a similar pilot program, calling it “The Greener Cow.”
Pasture is the best way to feed that greener cow. A diet rich in natural omega-3 fatty acid sources such as grass, alfalfa and flax rebalances a cow’s rumen, so she gives off less methane, explained Nancy Hirshberg, Stonyfield’s vice president for natural resources. In addition, omega-3 provides many benefits for human health, as anyone who walks down a supermarket aisle knows today.
But even if they’re pastured, most Northeast and Midwest dairy cows eat a ration heavy in corn and soy during the winter. One of Stonyfield’s goals is to find a diet that will maintain the omega-3 benefits of pasture year-round.
Its pilot project, started 18 months ago, comprises 15 Vermont dairies, divided into three groups. During the last two winters, one group fed rations with 6 lbs. of flaxmeal; another group, 3 lbs. of TradiLin, flaxseed that’s undergone a patented extrusion process; and the third, a control ration.
A trial by French researchers Y. Chilliard, M. Martin, et al, published in the Journal of Dairy Science last fall, found that extruded flaxseed can change fatty acid composition and decrease methane per kilogram of milk by as much as one-third, said Stonyfield.
Preliminary results of Stonyfield’s study found an average 12% reduction in methane emissions on the dairies feeding flax. But it also found that omega-3s in the milk increased by 29%, while the ratio of omega-6 to omega-3 was lowered, a ratio considered a key to human health.
However, TradiLin is currently only processed in Europe, by the French company Valorex SAS, so is a costly alternative.
“The big unknown is how to make it work economically for every farm that wants to adopt it,” Hirshberg said.
Final numbers from the pilot project won’t be available until spring, but Guy Choiniere said he’s happy with results on his dairy. He dairies with his family in Highgate Center, Vt., and had his farm certified organic in 2005.
Choiniere, whose herd is on pasture from May 15 to October 15, said grass can’t be beat for feed, as long as it’s well-managed.
“Just because they’re on grass doesn’t mean you’ll have the same profile,” he said. “You have to manage grazing to have it be high in omega-3.”
But Choiniere is looking for a feed on which his cows will do as well for the seven months they’re in the barn as they do on pasture.
Before joining Stonyfield Farm’s project, Choiniere knew that grass-fed cows produce fewer methane emissions. So it didn’t surprise him that Stonyfield’s analysis showed his 75-head herd cut emissions by 25% after eating a ration high in omega-3 for three months last spring before they went out to pasture. In his second winter of the trial, Choiniere said he’s seen the same benefits he saw last year – improved appetite and better overall “attitude” – after bringing his cows in from fall pasture.
Over the last five years, Choiniere has cut back grain from 25 lbs. per cow to 12 lbs. For the study, he replaced 2 lbs. of cornmeal in their diet with 2 lbs. of the processed flaxseed. “Higher omega-3s are more friendly to the (cow’s) gut, so it’s operating more efficiently,” he said. “When you get a tractor operating efficiently, you’re going to get less fumes coming out of the muffler.”
He manages his herd for high fall production, yet didn’t see the usual spring fall-off in milk production.
“It brought my cows to a summer level,” he said. “Grass takes all your problems away, and I saw those improvements in the winter. And the manure texture changed – I saw grass texture in the winter. They had improved appetite and cud chewing. And the hair coat – all of a sudden, a shine came over them. Those are the visuals that I could see.”
Choiniere said his herd has maintained its milk production, settling around 57 lbs. per cow after a high of 58 lbs. in December.
Components are a different story. Although protein has stayed the same, butterfat levels dropped from about 4% before feeding processed flaxseed to 3.8% now.
Milk fat depression may be one of several drawbacks. While research has found feeding flaxseed does lower methane emissions, there are some risks involved. Depending on the amount of flaxseed fed and the method of processing, it could decrease milk production, milk components and feed digestibility.
So this approach is not without controversy. Is omega-6 that bad? Is omega-3 that good? If so, how can the omega-3 content of milk be increased?
Altering the ration is just one method of lowering methane emissions on dairy farms. Using fatty acid sources to achieve nutritional and environmental results isn’t cut and dried, since it involves many interlocking factors.
One approach to cutting back on methane emissions, on a per-pound-of-milk-produced basis, is feeding and managing cows for higher levels of milk production, indicates Larry Chase, a Cornell University professor of animal science. At the 2008 Mitigating Air Emissions for Animal Feeding Operations conference, he listed a number of other factors that could be used to lower methane emissions. These included genetics, recombinant bovine somatotropin, higher quality forages, altering rumen fermentation with monensin, and adding fat sources, such as flaxseed or fish oil, to rations.
Dale Bauman, Cornell’s Liberty Hyde Bailey professor and a leader in research to extend the field of dairy nutrition beyond the cow to the environment and consumers themselves, takes issue with Stonyfield’s claim that boosting omega-3 amounts in milk is a step forward. The amount of omega-3 fatty acid in milk fat in the first place is so small that the increase due to feeding oilseeds would not represent a meaningful contribution to human requirements, he said.
He also says the form of omega-3 fatty acid – alpha-linolenic acid – that is affected by feeding these particular oilseeds is a type of little use to humans, because they can’t convert enough of it to the useful long chain omega-3 fatty acids.
One of Bauman’s research goals is find out how to increase the milk fat content of the valuable long-chain omega-3 fatty acids, as well as conjugated linoleic acid (CLA), another fatty acid with health benefits. But that is difficult to do without causing milk fat depression.
“Our work has focused on supplying the polyunsaturated fatty acid precursors for rumen bacteria, while minimizing the shift in rumen fermentation associated with the decreased diet digestibility and milk fat depression,” he said. “To date, we have not found a way, when corn-based diets are used, that consistently increases CLA while mitigating the milk fat depression risk.”
Whatever the path, the goal is worth working toward, said Charlie Sniffen of Fencrest LLC, former ruminant nutritionist for W.H. Miner Agricultural Research Institute, Chazy, N.Y. “Anything we can do to have a smaller footprint and increase energy efficiency, let’s do it.”
In addition, the human health angle can only help dairy producers.
“It’s becoming obvious that there’s an opportunity for niche marketing by creating the right kind of fatty acids in milk,” Sniffen said. “Other countries are farther advanced. In the Asian market, there’s a huge interest to the omega-3 approach. They’re working hard to develop products to enhance omega-3 concentration in milk.
“So it’s going to happen, no doubt about it,” he continued. “Part of the marketing work has already been done for us by the egg producers; now we, dairy, have to deliver.”
One tool that’s helped Guy Choiniere feed his herd profitably is a robotic round bale feeder that moves automatically along the feed manger of his tiestall barn. “That’s increased dry matter intake by 30% because it stimulates appetite through one bite at a time,” Choiniere says. “There’s no slug feeding – they’re always aggressive, always hungry. They don’t like to see it go by without taking a bite.” The feeder helped him replace 10 lbs. of grain with forage.
And Choiniere hasn’t bought any protein concentrate in the last five years. “Once you realize that a cow only needs 17% to 18% protein, as long as you can make high-quality feed, only high-energy grain is needed,” he said.
High-quality feed starts with the soil, he said. Feed the soil well and your cows will eat well. That means making sure soil micro-organisms get four essentials: air, water, organic matter and minerals.
Choiniere raises his hay and stores it in Ag Bags, on 150 acres on a nearby farm. Four years ago, he seeded those acres to 30% legumes – clovers and alfalfa, and the rest to a mixture of grasses, mainly tall fescue. He applied manure heavily that first year. He uses a refractometer to measure sugar levels in the grass to decide when to harvest.
Hay yields went from about 2 tons per acre to 4 to 5 tons, with no added manure applications. Now he’s turned his attention to reclaiming played-out pastures on the home farm, filling in with clay and aerating the soil down about 8 inches, followed by a heavy manure application.