Producers in the southeastern U.S., where drought is contributing to a short hay supply, should know how much hay and pasture they have available and how much will be needed to get through a dry period, said Dennis Hancock, University of Georgia Extension forage specialist.
Once a feed inventory is taken, calculate beef cattle feed needs on a body-weight basis, assuming each cow consumes about 2 lbs/head/day for every 100 lbs of body weight. “A 1,200-lb cow, at 2% of her body weight, each day is going to be consuming about 24 lbs/head/day,” he said during a drought management webinar hosted by University of Georgia and University of Florida experts.
Yet, if the cow isn’t grazing efficiently – say only at around 50% efficiency – she’ll need up to 48 lbs/head/day of forage, Hancock warned.
The forage specialist also suggested using a hay ring or limit feeding to keep losses and nitrate levels as low as possible. When feeding hay, do so in areas that need soil building. “We can add nutrients as well as organic matter given to us from the excess hay.”
Avoid high-starch supplemental feeds. Using low-starch energy supplements will stretch a producer's hay supplies and optimize the digestibility of the fiber sources in the diet, he said.
But hay isn’t the only feed in town. Another option: drought-stressed corn. It can be cut for green chop, baled for hay, grazed or ensiled as silage or baleage. “Grazing is probably the most cost-effective harvest option,” said Hancock, “but if nitrates are high, the best option would be to ensile it.
“That’s the only way that we can effectively reduce the nitrate levels in the forage. By making silage or baleage out of the crop, we can reduce nitrates by 50-60%.” For more information, view the video Hancock produced on harvesting drought-stressed corn at http://www.youtube.com/watch?v=RdyfCfjhIws&feature=youtu.be.
Be sure to increase cutting height, which will decrease nitrate concentrations, he said. “I would recommend to go ahead and sample at a 3-4” cutting height just to establish what the high end of the range will be when one gets ready to harvest it.
“Then we definitely need to sample again before we feed,” he added. For beef cattle, nitrate levels in the ration should be less than 4,500 ppm; for dairy, 2,500 ppm or lower; and for early lactation dairy cows, under 1,500 ppm.
Abandoned crops or crop residues – such as drought-stressed soybeans or residues from cotton, peanut, snap-beans, sweet corn, or other vegetable crops – could add to the forage inventory. Many can work in grazing systems, but producers with these abandoned crops or residues may need to have the forage removed from the field as hay and baleage.
“As a rule of thumb, we can get about 30 days per cow out of about 2,000 lbs of residue. If we frontal graze that or strip it off in some way, we can make that go a little bit further as we need to.”
Hancock also suggested that producers consider growing water-efficient summer-annual grasses, “particularly if rainfall becomes more frequent as we go through the summer. Even though we may never catch back up in terms of soil moisture, this may be an opportunity to find whatever little moisture we are getting out of those rains that come sporadically through in the summer.
“If you have a situation where only a small area can be irrigated, this is also an opportunity where we can take a look at focusing those water resources on a crop that is going to be extremely water-use efficient and allow us to grow up some forage with a limited amount of water.”
Pearl millet is probably the best warm-season annual option because it’s more productive than most other summer annuals under severe drought conditions. It does a good job of tillering in and is easy to manage under grazing. It doesn’t have any prussic-acid toxicity issues but can develop toxic nitrates and is sometimes less palatable under severe drought stress.
“One concern we have about any summer annuals, though, is if we are planting late, we are going to see a drastic reduction in the total yield potential of that crop,” he said. In yield trials, pearl millet planted in late June or later produced only a third of the yield of crops planted at recommended dates.
Brown top, foxtail and proso millets are other summer-annual options, “but all have a tendency to accumulate nitrates perhaps more than any other of the summer annuals. So be very, very careful about those in an emergency forage situation.”
Hancock also warned producers that drought alone doesn’t usually kill pasture species. “Drought in combination with poor fertility, overgrazing, pest problems and competition with other warm-season species can kill or reduce our stands pretty severely.”
But overgrazing is probably the most important factor affecting stand density, he said. “That’s where we really need to be careful about leaving enough residue there for the crop to grow back.”
Also limit grazing damage by confining animals to a sacrifice paddock or pasture already in need of renovation.
“Cattle come and go, but eventually we’re stuck with whatever we do to our pastures. To be honest with you, after the 2007 drought we lost a lot of stands throughout the state mainly because of how severely overgrazed they were.
“So it’s important to allow that pasture to recover by leaving enough stubble there for it to grow back from. The absolute minimum for bermudagrass is 2”; bahiagrass, 1½”; and for tall fescue, 2-3”. Then reintroduce those pastures slowly.”
For information on what cool-season annual grasses Hancock recommends producers consider, see the full presentation at http://www.caes.uga.edu/commodities/fieldcrops/forages/events/drought/110620forages.pdf.