Perryman seeks to solve the forage kochia mystery
Several years ago, a number of cattle grazing on Nevada rangeland began mysteriously dying of a condition known as frothy bloat, which is a build-up of foamy gas that can't easily be expelled and can accumulate to the point where the animal suffocates and dies.
When researchers began examining the animals, the only common thread that ran through each death was a high content of the plant forage kochia in their digestive systems. Was that the cause of the frothy bloat? Or had the cows eaten forage kochia along with some other plant that combined to cause the condition? And if it had been a combination of forage, what is the combination that triggers the potentially deadly condition?
CABNR's Professor Barry Perryman is setting out to find the answer to the mystery.
"It doesn't do much good to just analyze forage kochia without comparing it to something," Perryman said. "We need to compare it to alfalfa and grass mixes and analyze the nutritional quality as well as the amount of crude protein and so forth.
"One of the things that we found initially is that the problem with frothy bloat happened in the fall. That's the only time we were made aware of cattle dying this way. Well, the fall is when forage kochia is the only green plant out on the Nevada rangeland, and that attracts the animals. So we thought it'd be a good idea to take a look at it."
Perryman will be conducting his study with Prof. Tamzen Stringham and research faculty member Teshome Shenkoru. Parts of the study will be conducted on the Main Station Farm and Gund Ranch outside of Austin.
Dr Barry Perryman
Forage kochia is not a plant that is native to Nevada rangeland. It has purposely been added to seed mixes and spread over thousands of acres of Nevada rangeland as a way to add grazing material to the land when it is naturally in short supply. Seeding with forage kochia is also a way to rehabilitate scorched or otherwise barren ranges. As a result, forage kochia now thrives across wide swaths of northern and central Nevada, along with other nonindigenous shrub species, and is readily eaten by both wild and domestic grazing animals.
Forage kochia has been consumed by grazing animals in central Asia for millennia, adding vital crude protein to the animals' diet at time when pickings on the range are slim. Studies have show that cattle wintering on forage kochia gain weight and add condition, and some researchers have recommended combining forage kochia with 25 to 50 percent dry matter as an optimum diet for penned steers.
But the researchers who developed forage kochia as a way of supporting grazing animals during lean times didn't anticipate that the plant could hurt cows under certain circumstances, Perryman says. Most of the deaths occurred within the mid- to late-fall time period when the cattle were using the range and likely consuming a lot of forage kochia, whose small leaves increase the potential for cows to retain the dangerous gasses.
Perryman's study will determine the bloat potential of six different diet rations, from 100 percent alfalfa and 100 percent forage kochia to a combination of forage kochia and grass hay. Perryman expects the 100 percent forage kochia to produce as much or more gas and foam as the pure alfalfa diet. More importantly, Perryman hopes to develop some guidelines for ranchers whose cattle feed on forage kochia. He doesn't think cattle will have to be kept off forage kochia entirely, or that the nonindigenous shrub needs to be eliminated from the range.
"I think forage kochia has great potential under the right circumstances," he says. "As a forage and a fire break, it's not a bad plant to have out there. It just has this downside that has to be better understood. We'll just have to manage around it. We just need to know what the characteristics are that lead to this acute bloat with these animals and maybe not allow them access to it when they are exceptionally hungry."