Kansas State University’s Beef Systems Specialist Jaymelynn Farney is investigating how cattle choose what to eat.

Farney, who is at the Southeast Research and Extension Center in Columbus, Kansas, has been performing studies on what forages cattle prefer. She’s using summer cover crops, or annual forages, in re-purposed protein tubs. They’re then offered to cattle to determine preference.

“I have grown eight plant species in each growing period and offered the plants to the cows in two 24-hour sessions,” she said. “We recorded their behavior for the first hour after introduction to the plants and they were video recorded through the remainder of the time to see which plants they completely consumed and in which order.”

The study wants to help producers make decisions about which cover crops to plant when incorporating grazing.

“There is a laundry list of plants that contain useful cover crop benefits and it becomes daunting to select the species that will meet your operation’s objectives,” Farney said.

When deciding what plant species to sow, Farney said there are two trains of thought.

Purposefully plant only those species that cattle will consume to maximize land usage or gains along with capturing some cover crop benefits; or

Strategically plant species that cattle are averse to in order to leave appreciable biomass in the field for soil health objectives.

“With these two things in mind I was interested in seeing how cattle that were completely naive to cover crops consumed these plants,” Farney said.

Initially, Farney has found the most preferred plants include: Barley, Austrian winter pea and Graza forage radish (tie), mustard, Impact collard, Trophy rape, and purple top turnip (all fairly the same in preference). Last was Bayou kale. Her preference information was collected prior to a freeze.

“Stay tuned to next year to find out what their preference to these same species are when grazing after a killing freeze,” Farney said.

For summer grazing, in order from most preferred to least includes: Brown mid-rib forage sorghum and sorghum-Sudan (tied for first), pearl millet, Black oil sunflower and sun hemp (tied for third). Least favorite with little to no difference (strongly objected) were mungbean, okra and safflower.

Farney said there is some learning in both the cattle and the researchers associated with these summer grazing plants.

“The first day exposed nearly all the cows did not even try the okra, but the second day they consumed them before mungbean and safflower,” Farney said. “Another interesting comment about the summers, all grazing occurred when the sorghums were 2 feet tall to minimize prussic acid issues.”

For the sorghums, grazing occurred 35 days after planting. The sunflowers in that time frame were very small and immature (6 to 8 inches tall at the most) while the mungbean and okra had leaves that were over 7 inches in diameter.

“Preference studies become difficult to quantify as cattle do learn and modify grazing behavior especially after that first introduction to new plants,” she said. 

When in drought

Farney suggests spending some time to determine the plant species with more drought tolerance.

“I would stay away from really expensive components of mixtures because there is a greater chance of crop failure with no moisture,” she said. “There is some literature that shows that a few different plant species as a cover crop have some environmental lee-way.” 

For stocker cattle

Farney leans heavily on the grass component of a stocker cover crops plan.

She limits brassicas to a 1 pound per acre with maximum of 1.5 pounds of brassica seed per acre. Amounts over this can cause the brassicas to outcompete the grass species and reduce grass tonnage. For fall forages, the grass and brassica species offer enough protein to the animal.

“Younger calves have a stronger aversion to the broadleaves and brassicas than cows do and this can potentially hamper gains for a short duration until they begin to consume these plants,” Farney said

“In Kansas, from my research and measuring producers fields, we rarely get any fall growth of legumes,” she said. “This is an expensive component of the mixture and with the combination of low to no-growth and no need for additional protein to meet calf requirements, I do not include legumes in fall covers.” 

Farney suggests oats and barley—both spring and winter varieties—to those looking to graze something other than native grass as they offer the earliest, quickest growth. Triticale is intermediate and wheat and rye will have the majority of their growth late winter and early spring. Turnips and radishes have a very rapid growth rate, but once a freeze happens, they don’t generate any more dry matter. Grass species continue to have some growth as the season goes on.