Saving the environment one legume at a time

Condensed tannins reduce bloat and do a whole lot more besides

In the environmental debate, some rank cattle up there with smokestacks and auto emissions.

But Canadian researchers are discovering Mother Nature has developed her own mitigation strategy for bovine burps, flatulence, and excrement — and showing that grazing cattle has major environmental benefits.

Allan Iwaasa

Allan Iwaasa
photo: Supplied

In 2000, concerns over cattle and greenhouse gases prompted Allan Iwaasa of Agriculture and Agri-Food Canada’s Swift Current research centre to launch a study to see what happens when cropland is seeded to pasture. The fields, which had been cropped since the 1920s (despite having marginal soils) were seeded to two different native perennial mixes. There was a simple mix of seven species of cool-season grasses and a complex one with 14 species of cool- and warm-season grasses. Both included a legume — purple prairie clover.

The latter eventually caught the attention of Iwaasa and his research colleagues.

“We noticed the animals enjoyed grazing the purple prairie clover,” he said. “So five years ago we looked to see if there were some benefits from the purple prairie clover in regards to having condensed tannins. We then, with the help of (colleague) Yuxi Wang, started looking at how the purple prairie clover condensed tannin levels compared to sainfoin. The purple prairie clover had some of the highest levels of condensed tannins that we were able to find for any of the tame or native species that we were evaluating.”

Sainfoin’s condensed tannins protect against bloat, and many Alberta producers have been anxiously awaiting the commercial availability of AC Mountainview, developed by Ag Canada forage breeder Surya Acharya in Lethbridge and currently being increased for seed sales by Northstar Seed. (It’s expected to be available for sale next year.)

Older sainfoin cultivars, such as Nova and Melrose, were generally single-harvest-type sainfoins; did not persist long in alfalfa mix stands; and didn’t regrow at the same rate as alfalfa after grazing or cutting. However, Mountainview has better regrowth potential and Iwaasa is conducting research comparing the Canadian Mountainview sainfoin to the U.S. Delaney sainfoin which also has traits for multiple cuts.

Other benefits

Like purple prairie clover, sainfoin is high in condensed tannins and Iwaasa’s research should add to the anticipation of graziers wanting a source of condensed tannins in their pastures. That’s because they appear to offer benefits beyond bloat reduction.

“Condensed tannins associated with purple prairie clover result in a reduction in E. coli shedding by the ruminant animal,” said Iwaasa.

This finding could have a huge impact in terms of food safety and also mitigating contamination during run-off, especially when there are large numbers of animals in concentrated areas, such as dairies and feedlots.

“We have been able to show that the pastures have this beneficial effect by reducing E. coli shedding in the animal dung,” said Iwaasa. “We are trying to quantify the amount of purple prairie clover in the mixture that will give us the most bang for our buck.”

Another potential benefit of condensed tannins being studied is their potential to reduce methane emissions.

The researchers have also looked at carbon sequestration in pastures and are studying a mix of alfalfa — a.k.a. ‘the queen of forages’ — and sainfoin.

“Currently we are looking at the different sainfoin germplasms that were used in the development of AC Mountainview, and some of these sainfoin germplasms and U.S. cultivars may be better suited to grow in southwest Saskatchewan and arid areas of the Prairies,” he said.

Although alfalfa fixes more nitrogen, sainfoin is very palatable and preferred by grazing cattle. By utilizing the new cultivars there may be opportunities for the animals to select the sainfoin and reap the benefits of the condensed tannins over a long period of time.

But Iwaasa’s ongoing research also has a big-picture focus — not just the performance of the sainfoin-alfalfa mixture itself, but also nitrogen fixation and carbon sequestration back into the soil.

“We are measuring the amount of nitrous oxides and other greenhouse gases being emitted by the animals; looking at the benefit of a perennial forage that animals can utilize in the field; and all those nutrients being recycled back into the system and still promoting the production of that forage,” said Iwaasa.

What started as a response to criticism of cattle emissions is leading to discoveries that could boost production and the environment at the same time.

“Looking at grazing management and utilizing our land base with environmentally sustainable practices will benefit not only the producer, but the public as a whole,” said Iwaasa.

About the author

Contributor

Jill Burkhardt

Jill Burkhardt, her husband, Kelly, and their two children, own and operate a mixed farm near Gwynne, Alberta. Originally hailing from Montana, she has a degree in Range Management from Montana State University. Jill’s agricultural passions are cattle and range management but she enjoys writing and learning more about all aspects of farming.

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