KINGSVILLE, Texas (AP) - It's not often that operators of the King Ranch hold an auction on the spread that's larger than Rhode Island.

The ranch's first cattle and horse sale in 20 years is scheduled Saturday, in conjunction with its sesquicentennial celebration. The ranch, where livestock is stamped with the running W brand, is home to one of the world's largest cattle herds.

For weeks, ranch hands have been monitoring and pampering the cattle for the auction.

Owners hope that high interest in the rare sale, fanned by King Ranch anniversary nostalgia, will generate huge donations at a charity auction benefiting a new institute that is being created to mark the 150th anniversary.

Proceeds from bidding on registered longhorn cattle, a handcrafted saddle, hunting trips and other high-ticket items are earmarked for the King Ranch Institute for Ranch Management at Texas A&M University-Kingsville. The institute holds its first technical symposium on Wednesday as it prepares students for careers at large ranches.

"It's an acknowledgment that running these large ranches is much more complex than it was 20 or 30 years ago," said Jack Hunt, president of Houston-based King Ranch Inc. "The hunting values are so great now, particularly for people who've done as good a job as King Ranch has in taking care of its resources. That goes all the way back to the early 1900s. King Ranch was a pioneer there."

The ranch, founded in 1853 by Capt. Richard King, covers 825,000 acres in four counties and is renowned for breeding Santa Gertrudis and Santa Cruz cattle and quarterhorses. Some of the 21 horses being sold have been training trained to work with cattle, and all have been acquainted with human crowds and noises.

"We put a lot of work in them," retired horse handler Emeterio Silguero Jr. told the Houston Chronicle in Monday's editions. The fourth-generation, 20-year ranch employee spent the past 10 months readying the sale horses.

Cody Crider, a Kerrville native who oversees the horse operation, said he has been swamped with inquiries about the sale horses.

"As a kid, I had horses that had King Ranch bloodlines in them. Me ending up here is really a dream come true. It's an honor. And then to be here during the 150th celebration, it's pretty incredible," he said.