Invasive grasses can hurt pastures

While downy brome is green for a time, to the trained eye it provides only the illusion of quality. This managed area shows how early growth turns quickly into lesser valued feed and chokes out other species.  |  Bruce Derksen photo

Just because it’s green out there doesn’t mean it will make your wallet that way or keep your cattle happy

For some cattle producers, the positivity of spring’s green grass is just a colourful illusion. Green represents new growth and vitality but if this grass is of the invasive annual cheat grass variety, also known as downy brome, optimism quickly fades.

It is a common issue throughout the United States Great Plains, Great Basin and western states. In the last few years, it has also crossed into significant portions of Alberta, Saskatchewan and Manitoba.

Justin Hossfeld, Agricultural Specialist for Out West Agriculture and Engineering, Wyoming, knows the business of cattle ranching, return on investment and especially grass.

Growing up on the Padlock Ranch in northern Wyoming and later becoming general manager of the Sunlight Ranch straddling the state border with Montana, he saw first-hand the difference between high quality perennial grass and forage and pasture overtaken by invasive bromes. Both these ranches are large grazing operations sharing the common denominator of considerable amounts of annual brome grass infestations.

“We were trying to be good stewards of the land and pull the most pounds of beef per cost of input, but annual grasses were impeding our grazing rotations. They greatly impacted forage quality forcing us to spend money on supplements to help the cattle harvest this kind of a resource and hopefully pull some performance from it. Throughout my career in the ranching industry, annual grasses always made us attempt to cope with it or manage around it.”

While downy brome is green for a time, to the trained eye it provides only the illusion of quality. Hossfeld says the problem is the life cycle and life span of the plants. “They are a winter or fall annual plant,” he said.

“They germinate in the fall, sprout two or three miniscule leaves and remain fairly dormant through the winter. But as soon as the weather warms up and the snow melts, they bust out and start to grow, harvesting most of the available nutrients.”

He adds one generation of downy brome can drop up to 18,000 seeds per square yard. When germinating, they become a literal carpet appropriating the nutrients and moisture before the desired perennials begin to grow. By late May and June, they mature and wither turning a purplish red colour.

Usually by late April, the plants develop extremely abrasive, sharp and pointed seed heads, which become unpalatable causing mouth sores and eye injuries.

Hossfeld says cattle eventually give up trying to consume them and begin over-grazing non-infested pasture. This in turn assists the invasive bromes to spread and further propagate.

By stealing the majority of pastureland resources year after year, they force desirable perennial pastures into a state of inactivity. “From an operational standpoint, it chokes them out and establishes a state of dormancy by grabbing the nutrients and moisture the perennials require to be prolific and provide a benefit to the rancher.”

Three main impacts of invasive brome grasses

Hossfeld outlines three main impacts these grasses have including an effect on livestock performance, a suppression of harvestable acres and plants and a reduction in return on investment for the livestock producer.

One of the ways the ranching industry measures the amount of nutrition in forage resources is with a total digestive nutrient scale. Non-infested rangeland normally registers a TDN percentage value in the mid to upper 50s. Where invasive grasses are a problem, the TDN is rated at about 35-38 percent.

“That doesn’t sound like a lot, only 20 points, but in the forage resource game, it’s huge,” said Hossfeld.

He explains when forage quality is this low, cows are forced to eat roughly 10 pounds of extra feed per day, or about 300 lb. extra per month to meet their nutritional needs.

“Even then, it’s not really meeting her needs. Ten lb. of forage in a day is a lot. It would barely fit in a garbage can. This puts a lot of pressure on the system when you think of all the grazing animals out there, and not just livestock.”

He says ranchers buy forage supplements to support this poor-quality feed, but cattle don’t perform as well on them. In good perennial stands, cows actually eat less material. They meet their nutritional needs quicker in the day and lie down earlier to digest their food, putting less pressure on the ecosystem.

Acreage performance is the second component affected by invasive bromes. Since cattle find them unpalatable during the spring, they abandon these acres and are forced to areas supporting superior perennials.

The overuse of these nutritious acres cause the resource to be quickly consumed. Tops of plants are eaten first in proper grazing, but as this growth disappears, cattle eat the remaining coarse materials. Not only are they consuming a lesser quality, but they are also damaging the overall welfare of the perennials.

The third impact becomes the financial effect and return on investment for the entire farm or ranch. Hossfeld described from experience how ranches would often be forced to bring cattle off the pastures in October or November. “It wasn’t because we were snowed under, but because we had cycled through all of our pastures and utilized or over-utilized the non-infested acres. Trying to be good stewards and leave our pastures in any kind of shape for next year, we had to bring cows in to start feeding.”

“When annual grasses are removed from the picture, tools become available to the producer,” he said. “Protecting desirable, palatable, nutritious forage is money in the bank.”

Less hay is fed, with some possibly freed up for sale creating cash flow opportunities. A grazing buffer might be maintained for later in the season or as an additional grass bank for the next spring should snow arrive early.

Ranchers might have available pasture to lease out creating extra mid-summer income. Additional grass could be held to feed fall cull cows longer, allowing them to gain more weight and value for a sale in the subsequent year instead of when most of them hit the market in November and December.

“Ranchers have this huge resource, which is their most expensive and valuable asset — the one their operating loan and operation is centred around paying for, but they’re just not using all the acres because of the presence of this grass,” says Hossfeld.

He believes there is hope as perennial pastures are hardy and will bounce back becoming prolific again when given the moisture and nutrition required. “They quickly fill the open spaces and start to re-populate. The ripples in the pond from removing these annual invasive grasses are huge.”

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