When Ball's Bluff was donated to Virginia Tech's Middleburg Agricultural Research and Extension Center in 1996, veterinarians there expected the 5-year-old retired racehorse to do nothing more than breed foals to be used in studies on pregnancy and foal development.

However, in one of those twists that make the racing world so unpredictable, the 13-year-old stallion, who was a "decent" racehorse at best, is now the top-ranking sire of sprinters bred in Virginia based on earnings, said officials at the research facility, known as the MARE Center.

Eight of his 80 offspring are racing this year, and they have earned more than $200,000 so far, a figure that also makes Ball's Bluff the third most valuable stallion for Virginia-bred foals racing in sprints as well as longer races, according to the Bloodstock Research Information Services in Lexington, Ky.

One of his offspring, a 4-year-old filly named Bluffie Slew, has earned about $150,000 since she began racing a little more than two years ago. On her mother's side, the dark brown filly is one of thousands of granddaughters of Virginia national racing legend Secretariat, according to Evan Hammonds, managing editor of the Blood-Horse, a Lexington-based magazine.

Bluffie Slew's owner, Warren Owens, 53, of Sterling, grew up in Middleburg and dreamed of racing horses from the time he was young. He purchased Bluffie Slew at a yearling auction at the MARE Center in 2001 for $3,000. That year, the average price for yearlings was more than $50,000, and the median price was nearly $10,000, according to the Jockey Club's 2004 Fact Book, an industry standard for statistics.

This year alone, Bluffie Slew has earned nearly $90,000, including $50,000 on July 4 when she won a race at Colonial Downs in New Kent County, southeast of Richmond. However, less than two weeks later, she came in last at a race at Delaware Park in Wilmington, where she lives and trains. She is scheduled to race next at Saratoga Race Course in Saratoga Springs, N.Y., on Friday.

Virginia has only about 70 breeding stallions. Racing powerhouse states such as California, Kentucky and Texas have nearly 400 each, with the leading sires earning millions.

Because Ball's Bluff is competing against a smaller group of stallions in Virginia, his state ranking is relatively high. But he is still a lucky horse, according to industry experts.

"If Ball's Bluff was anywhere else [besides the research farm], he wouldn't have had a chance as a stud," said Mark Deane, a field director at the Virginia Thoroughbred Association.

"He's really bucking the odds," said Deane, referring to the small proportion, just 3 percent, of male thoroughbred horses in the United States, Western Europe, Japan and Australia who end up breeding.

Ball's Bluff is not available commercially for breeding. He breeds only with the MARE Center's resident thoroughbred breeding mares, many of which were also donated to the research center. Some of the nearly 50 mares were bred as show horses, where what matters is appearance, not racing ability.

During Bluffie Slew's first year at the MARE Center, she was part of a diet study to see how different feeds affect growth and development. She received a special, lower-carbohydrate version that was higher in fiber and fat than standard feed.

The popular, commercially available product, commonly referred to as "sweet feed," has a lot of grain and molasses, said Tania Cubitt, a doctoral student at Virginia Tech studying pasture-based equine nutrition related to reproduction. The center's special "fat and fiber" feed is low in sugar and starches, contains corn oil and looks like chopped grass, she said.

Ball's Bluff gets some attention from Jim Bowen, interim director of Virginia Tech's Middleburg Agricultural Research and Extension Center. Ball's Bluff has sired 80 offspring. Eight are racing this year, and they have earned more than $200,000 so far.