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Keeping Methane In Check

Manitoba Agriculture Food and Rural Initiatives recently announced $1 million in funding for research into reducing greenhouse gas emissions (GHGs).

Cattle are the main source of methane emissions in Canada, says Dr. Karin Wittenberg, associate dean of research in the agriculture faculty at the University of Manitoba. Canada’s livestock production systems contribute about 58 per cent of the total agricultural GHG emissions according to data from Agriculture Canada, with beef and dairy cattle accounting for 97 per cent of total enteric emissions.

Dr. Wittenberg and colleague Dinah Boadi have identified a number of ways in which methane emissions from cattle can be reduced by changes to their diet. One study, conducted in 2004, compared animals on a low forage to grain ratio diet with those on a high forage to grain ratio and measured methane production from the animals themselves and the manure pack.

The study found that methane production was 42 per cent higher from cattle with a higher grain content in their diet and that this was in part related to the increased intake of those animals.

On the high-forage diet, vegetable oil was fed in the form of whole sunflower seeds to increase the energy content. This was the other reason for the lower enteric methane emissions in cattle fed a high-forage diet.

“When we add vegetable oils to the diet, like canola or soy or sunflower seeds, at a rate of somewhere between three and five per cent we get about a 30 per cent reduction in the amount of methane that the animals produce,” says Wittenberg. “So that is exciting, and that is a strategy producers could use depending on the cost of the oil. Some years it makes sense and other years it’s cost prohibitive.”

Adjusting the protein content in the diet is another effective way to help useful bacteria do their job more effectively, Wittenberg says. “If we ensure adequate nitrogen or protein in the diet we can optimize the microbial fermentation. Methane is being produced by bugs in the rumen, so we want to make sure that they, at the very least, get enough protein to be efficient in the breakdown of plant fibre to generate energy for the animal and for themselves. Inefficient fermentation in the rumen can result in high energy losses as methane.”

“Our current production practices can result in dietary energy losses of anything from two to 11.3 per cent of what the animals eat as being lost as methane,” she explains. “That basically means that when the diet is of lower quality and doesn’t really match what the animal needs, for every 10 bales the farmer is making, one is basically lost as methane from the animal. That is a lot of energy that is being lost and not being used for animal growth or milk production.”

Balancing the nutritional needs of the dairy or beef herd throughout the year represents ongoing research at the U of M based National Centre for Livestock and the Environment (NCLE). It’s looking at rotational forage systems as well as feed additives to determine which combinations are the most effective for both producers and the environment.

“If we can get an animal to slaughter weight at 13 months of age as opposed to say 20 months of age, that’s seven months that they are not on a farm or on a feedlot emitting methane,” says Wittenberg.

There has been much research over the years into developing additives for feed that improve feed efficiency and increase weight gain. One that has been widely adopted worldwide, particularly by larger feedlots, is the inclusion of ionophores (fermentation modifiers), such as monensin.

“Research had found that when ionophores were fed to ruminant animals like beef and dairy cattle the animals were much more efficient in how they used their feed energy and protein,” says Wittenberg. “And short-term studies showed that part of the reason they were more efficient was because they reduced methane emissions and energy loss because of the rumen microbes.”

Dr. Wittenberg’s longer-term research into ionophores has concluded that the effect of reducing methane emissions is transient, so not a good long-term solution to the issues of either GHG reduction or production efficiency.

“In two to four weeks depending on the type of diet the animal is on, their methane emissions go back to what they were before the ionophores were added to the diet,” says Wittenberg.

Ongoing work is focusing on the needs of cattle on pasture, which, Wittenberg says, has not really been looked at in terms of how the animals’ metabolism and digestive functions change during different seasons.

“In Canada the cattle herd is really on pasture most of the time and we have about 20 million hectares of forage land in Canada,” says Wittenberg. “This forage land is really the main source of energy and protein for the Canadian beef herd. Right now we are looking at when animals are exposed to cold trying to figure out how well they utilize nutrients and how efficient fermentation is because this effects not only the methane produced but also the manure characteristics which influence nutrient re-distribution in the grassland landscape.”

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