A two-year trial in Mississippi pitted kenaf against pearl millet and a mix of dallisgrass and bermudagrass to see which forage brought the best results in cattle production. More questions may have been raised than were answered, and Mississippi State University researchers would like to conduct the tests over a few more years to learn more.
Kenaf is a non-native annual that produces tremendous forage mass. It has a main stem with leaves that branch off it, and gets fibrous if allowed to grow tall. It is often used as an industrial fiber, but has many nutrients valuable for cattle growth.
Brian Rude, Mississippi Agricultural and Forestry Experiment Station ruminant nutritionist with MSU's Animal and Dairy Science Department, conducted the tests on MSU's South Farm in 1998 and 1999. He worked with Brian Baldwin, MAFES agronomist in the Plant and Soil Sciences Department.
“We chose to study kenaf because of the forage mass it produces. The nutrient crop is very good, it is pretty high in protein and the energy appears to be fairly available,” Rude said.
Kenaf appeared to be an acquired taste for cattle, similar to people learning to drink coffee.
“Once they got adapted to eating kenaf, they ate it well, and once they liked it, they actually preferred it to the other forages available,” Rude said.
There was a lot of rain the first year of the study, allowing the kenaf to grow quicker than the cattle grazed it down. The second year had drought-like conditions. During the first year, 72 steers grazed the three test plots for 56 days. In the second year, 45 steers grazed the three plots for 84 days.
Researchers looked for cattle weight gain during both trial years, and at the forage's digestibility the first year.
“Average daily gain during the first trial for steers grazing pearl millet was faster than those grazing dallisgrass or kenaf,” Rude said.
“Results of the second year's grazing study showed the greatest daily gain on kenaf, followed by pearl millet and then dallisgrass.”
Rude speculated that kenaf did not perform as well the first year because of less-than-ideal plot management and rain that caused it to grow quickly and get woody. The second year, researchers managed each of the forage plots for optimum performance, and cattle grazed on the kenaf while it was more leafy.
Another unusual result that surfaced involved digestibility. When calculated the first year, steers consuming millet appeared to digest and use nutrients more efficiently than those which fed on kenaf or dallisgrass, yet those feeding on kenaf had the best weight gain.
“The kenaf had a lower digestibility, but the cattle gained quicker, probably because the digestibility study grinds up both the stalk and the leaves while the cattle just graze the leaf and probably don't eat the stalks,” Rude said. “Energy is probably readily available in the leaf. We'd like to pursue this in other studies.”
In the study, all three forages were fertilized annually, but kenaf was the most expensive and had to be re-established each year. Pearl millet is another annual, but the seed is less expensive than kenaf seed. However, researchers found that kenaf can graze eight animals per acre and pearl millet can graze six to seven, while traditional summer forages such as dallisgrass and bermudagrass can graze just two per acre.
“Kenaf can carry more animals per acre and they will gain weight faster. That offsets the additional cost of the forage,” Rude said. “In our study, it was cost beneficial to use kenaf. With more research, we can isolate management practices we need to follow to be more consistent and precise.”
Rude said kenaf is not the answer to grazing issues in Mississippi, but it has promise. He suggested that small farms and those with diversified enterprises may benefit most from raising kenaf as either a fiber or a forage, depending on market prices.
Bonnie Coblentz writes for Mississippi State University Ag Communications.