By Kristin
Peterson
CenUSA’s
vision is building a sustainable biofuels and bioproducts system for the
Midwest based on switchgrass and other native, perennial grasses. Now two new studies,
led by Stephanie Hansen Iowa State University (ISU) assistant professor in
animal science and Daniel Loy, ISU professor of animal science, are evaluating the
use of switchgrass as cattle feed. Iowa State University intern Stephanie Clark
is assisting in the studies. If effective, farmers could have a new market and help
jumpstart grass production.
The first
experiment compares the feeding value of two roughages, corn stalks and switchgrass,
in a total mixed ration (TMR). TMR’s are a common method of feeding livestock
that mixes grain and chopped forage together with vitamins and minerals to meet
the nutritional needs of the animal.
Livestock TMRs might be compared to pet
food that we buy at the grocery store – only on a big scale! However, unlike
pets, cattle have rumens, special digestive systems, and require a certain
amount of roughage to function properly.
The second
study compares the digestibility of corn stalks and switchgrass, pretreated
with calcium hydroxide. Pretreatment has been shown to improve the quality of lower
quality forages that tend to be high in lignin (think wheat straw versus
alfalfa hay) by breaking down lignin and making the forage more digestible to
the animal.
Researchers
have seen some positive results in favor of switchgrass in terms of cattle acceptability.
In mixed rations, cattle seem to do a lot of nitpicking (or ‘sorting’) with corn
stalks but seem to eat more consistently with switchgrass. This may be because
switchgrass chops up finer than corn stalks, making a more consistent blend and
helping prevent ‘sorting,
Hansen
described the problem with sorting by comparing it to Skittles candy. Imagine
that you have a bag of Skittles and you need to eat all the colors in order to
get balanced nutrients. But, if you like reds the best you might go through and
eat all the reds first. Then, later, when you need another treat, you may go
back and eat your second favorite color: yellow.
A new market
for switchgrass could provide additional economic benefits from growing
switchgrass and could encourage more farmers to incorporate it into their
farmland.
“The more
uses there are for a product, the more likely it is that at any given time one
of the uses will dominate in terms of profitability,” Assistant Professor in
Iowa State’s Department of Economics and CenUSA co-project director, Keri
Jacobs. “Having more options for a product helps market development.”
Hansen believes
that the cattle trials show “good potential” for switchgrass as a forage crop.
“The best
place for switchgrass will probably be in feedlot type system where it is used
in fairly low levels as a roughage,” said Hansen. “To be used more widely as a
forage, it would have to be harvested earlier, when the plant is lower in
lignin and more digestible. But we’ll know more when the results are in later
this fall,” said Hansen.
