Mechanical hay-harvesting costs time and money.

A Purdue University specialist said livestock producers can save both by switching to nature's harvesting equipment: the animals.

Producers who practice what's known as "stockpiling forage" can extend the grazing season, thus letting the livestock do the work, said Keith Johnson, Purdue Extension forage specialist.

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"Anything we can do to allow our four-legged creatures to graze in a pasture beyond the traditional grazing season is a cost-effective approach," Johnson said. "By having the animals harvest the hay into December and, perhaps, January, producers can reduce the cost of delivering hay bales to them every day."

Forage stockpiling involves setting aside about 25% of a pasture around mid-August. The set-aside portion is left undisturbed to grow, while the remaining 75% will be harvested mechanically or grazed by livestock.

Stockpiling forage can be done when producers use a rotational grazing system, Johnson said. In rotational grazing, pastures are subdivided into smaller units -- or paddocks -- and livestock are moved from one paddock to another to give grazed areas time to regrow.

"The forage that is best adapted for stockpiling in Indiana is tall fescue, a cool-season grass," Johnson said. "Tall fescue continues to accumulate yield even when temperatures are quite cool into October. It's also not uncommon for other cool-season grasses and legumes to be part of a stockpiling program, too."

Annuals planted after winter wheat grain harvest can be components of the rotational grazing system in the late summer and into the fall, as well, Johnson said. Typical annual forage choices include sorghum-sudangrass, sudangrass, pearl millet, spring oat and forage turnips. Producers should be cautious when planting sudangrass and sorghum-sudangrass in the fall because prussic acid, a toxic compound, will be released from freeze-damaged plant tissue.

Whatever grass-legume combination a producer chooses to stockpile, a healthy pasture is vital, Johnson said.

"It's not unusual in a grass-dominant stand to think about applying 30 to 50 pounds of nitrogen per acre to grow more forage for grazing," he said. "Of course, with the cost of nitrogen fertilizer these days producers have to be wise about the amount that should be applied, when it is applied and the nitrogen source that is used.

"The nitrogen source is critical because some types, like urea, can volatilize in dry conditions. In addition, if a producer has at least 30% legume in a stand, that legume probably is providing enough nitrogen to grow a productive grass crop, so nitrogen fertilizer might not be necessary at all."

Producers might apply a herbicide in the paddocks designated for forage stockpiling to control perennial weed problems, Johnson said. However, herbicides used to reduce perennial broadleaf weeds also can kill the legumes a producer is trying to grow as a component of a pasture mixture.

"They'll have to decide whether it's better to address the weed problems or spare the legumes," Johnson said.

Other points to remember when stockpiling forage include harvest timing and the dry matter needs of livestock. Producers should stop haymaking operations approximately six weeks before a killing freeze, so that the forage can grow back and accumulate needed reserves for regrowth in the spring, Johnson said.

"Something that works well is allowing a hay field to grow its last crop and then bringing in livestock for a post-dormancy grazing, instead of performing a post-dormancy harvest with equipment," he said.

How many days a paddock can be grazed depends on the amount of forage produced, the dry matter intake of each animal and number of animals grazing in the paddock.

"It's not unusual for a cow that's just weaned her calf to require a daily dry matter intake of 2.5% of her body weight," Johnson said. "So, for a 1,000-pound cow, that comes out to 25 pounds of dry matter forage per day."