Forage Nitrates Hot Topic at Missouri Beef Tour

US - Zac Erwin stood by a drought-stunted field of Sudangrass as he talked to wagon-loads of field day visitors at the MU Greenley Research Center, earlier this week.
calendar icon 10 August 2012
clock icon 4 minute read

The University of Missouri regional extension specialist said the grass held toxic levels of nitrate and can't be used to feed the cow herd at the Agricultural Experiment Station east of Novelty. Mr Erwin, from Monticello, Missouri, was one of four specialists on the beef tour giving drought advice, including harvesting and ensiling.

Others of the 225 visitors were on wagon tours of crops and pests. The groups began gathering at 7 a.m. for a pre-tour breakfast.

Rob Kallenbach, MU Extension forage specialist standing in front of a dying corn field and rows of baled cornstalks, warned of dangerous nitrates caused by drought.

Too much nitrate can kill cows. But, more likely, lower levels can cause pregnant cows to abort their calves, Mr Kallenbach said.

Using cornstalks from the field, Mr Kallenbach put drops of test reagent on a fresh cut. The acid turned dark blue, showing a toxic level.

"That is a warning," Mr Kallenbach said. "A quantitative lab test is needed to determine actual nitrate level."

"You can pay for a lot of tests by saving one calf," he added.

County Extension Centers provide free initial test and give details on collecting samples for lab tests.

At the next stop, Daniel Mallory, extension livestock specialist, New London, Mo., gave strategies for efficient feeding this winter. That may require culling cows, to cut feed use.

"Make a list of those cows to go," Mr Mallory said. "First to go should be open cows. Invest your feed in cows that will make you money." A non-pregnant cow costs money a long time before she drops her next calf. If open, she goes.

Next will be cows with defects, lameness, bad eyes or bad attitude.

On the last stop, Justin Sexten, MU Extension beef nutritionist, outlined pros and cons of early weaning of calves to cut feed use.

Taking calves off the cows drops her feed needs from 2.5 percent of body weight to two per cent. "That gives you an extra day of feed every six days," Mr Sexten said. However, it increases care needed for calves. Young calves should be kept and fed. "Selling a 300-pound bawling calf is not a good marketing plan."

However, an early-weaned calf with a fully developed rumen for digesting forages can convert feed efficiently. Another advantage, dry cows will likely be ready for breeding season after a longer rest period. "Conception rates go up on cows that are gaining weight."

Several presenters said their field day topics changed because of drought.

Mr Erwin said: "I was going to show our new plantings of clover varieties. The take home message: Don't plant legumes in a drought." The grazing paddock of toxic grass will be seeded to rye for fall and spring grazing.

But, that depends on fall rains returning.

Mr Kallenbach advised farmers to prepare for a new grazing season. "The rains will return, we just don't know when."

The specialist said annual grasses such as rye, wheat, oats or triticale provide quick pasture. Oats produce the most tonnage, but won't survive the winter. The other cereals do.

Last fall, which was dry, the Greenley cow herd grazed on fall-planted rye. However the main use came this spring with early regrowth from the warm, wet spring. The rye paddock provided five weeks of grazing until early June for 36 cow-calf pairs from the spring-calving herd.

"You grazed 36 pairs on that small paddock?" one tour visitor asked. "It can be done," Mr Erwin replied.

The main message at every stop was "Don't waste feed this year. It is too expensive."

"If you've never tested your forage, this is the year," Mr Sexten said. The forage tests allow building low-cost rations. It's important to have cows in condition to rebreed and produce the next calf crop.

Field days give quick reviews of research and management practices for farmers to take home, said Randall Smoot, superintendent of the 700-acre farm donated to the University in memory of Lee Greenley, Jr.

At lunch, Marc Linit, associate dean of the MU College of Agriculture, Food and Natural Resources, said 2012 is the 150th anniversary of the Morrill Act, which established the land-grant universities. Later Congress added experiment stations and extension. "Those allow us to be here today transferring knowledge," he said.

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