* Wildfires burn nearly 775,000 acres in Nebraska

* Land is a grazing resource for about 40,000 cows

* Producers look for alternative pasture lands, feed

By Tom Polansek

CHICAGO, March 19 (Reuters) - Massive wildfires have

burned vast swaths of grazing lands in Nebraska, endangering

cattle producers' plans for production increases that could help

ease record-high U.S. beef prices.

The loss of grasslands in the second-biggest

cattle-producing state removes a feed source for herds and could

delay ranchers from expanding as they struggle with widespread

drought, state and industry officials said.

Fueled by fierce winds, fires have burned nearly 775,000

acres since last week, covering an area about the size of Rhode

Island, according to data from the Nebraska Emergency Management

Agency. It added the causes of the fires are undetermined.

The largest Morrill Fire was about 67% contained as of

Thursday after being first reported on March 12, the agency

said.

That amount of land is a grazing resource for about 40,000

cows, said Sherry Vinton, director of the Nebraska Department of

Agriculture. Though cattle deaths were thought to be minimal,

producers could delay expansion plans if they cannot find

alternative pasture lands or feed, she said.

"This will have a definite impact because you are in the

heart of cattle country there and that's the area where you're

going to primarily have breeding stock," said Vinton, a

fifth-generation rancher.

Nationwide, cattle inventories have dwindled to a 75-year

low over the past seven years as an extended drought raised

feeding costs and high prices drove producers to send animals to

slaughter instead of keeping them for breeding.

Tight supplies pushed up beef prices. They also hurt profits

for meatpackers paying more for cattle to slaughter, and Tyson

Foods ( TSN ) closed a large beef plant in Nebraska this year.

HERDS EXPAND SLOWLY

A larger U.S. herd could increase beef production and help

to bring down prices amid strong demand from consumers. The

rebuilding process has been slow, though, due to lingering

dryness, high interest rates that make it expensive to expand,

and concerns among ranchers over whether cattle prices could

sink.

The expansion process depends on favorable weather, said

Craig Uden, who raises cattle near Cozad, Nebraska, and is

president of the Nebraska Cattlemen industry group.

"When you have a setback like this and you actually go

backwards, it doesn't help," he said.

Uden, who purchased 200 extra mother cows in May as a

cautious move toward growing his herd, said dryness had slowed

expansion in Nebraska and the wildfires made producers feel less

confident that weather conditions would support larger herds.

His herd was not hit.

SEARCH FOR PASTURE LANDS

The search for alternative grazing lands could be difficult,

ranchers said, with 70% of the nation's cattle in areas

suffering from abnormal dryness or drought. Last month, fires

burned pasture lands in Kansas and Oklahoma.

In Nebraska, land set aside for federal conservation could

potentially be considered for grazing, Vinton said. Drought has

worsened after easing last summer, and ranchers said some cattle

will be moved out of state due to the fires.

Producers need options because they said it could take one

to three years to heal sandy ground that was damaged.

Fires also destroyed fencing and hay being stockpiled to

feed cattle during dry times, said Brenda Masek, a producer in

Purdum, Nebraska, and former Nebraska Cattlemen president. She

was hoping for rain to help burned land recover.

"If we don't get rain, there's going to be a lot of cattle

that are unfortunately going to have to hit the markets or be

shipped to a feedlot," she said. "It's definitely going to slow

the expansion of the herd."