Jim Ryan got into the breeding business by buying an $800 mare who, the seller assured him, was in foal to the horse who appeared on Page 1 of the Maryland Stallion Register.

The stallion's name was Adjutant General and, indeed, he was No. 1 in the alphabetical listing. Ryan soon found himself paying bills for an animal who finished last in seven straight races at Charles Town.

So it is not true that everything Jim Ryan touches turns to gold; it only seems that way to other breeders and owners who marvel at the phenomenal success of his Ryehill Farm in Mt. Airy, Md. Seldom has such a small operation produced so many good horses.

Ryehill Farm has never had more than 10 horses in training at any one time, but in the last five years it has won two Eclipse Awards with its fillies Smart Angle and Heavenly Cause. Its colt, Smarten, was syndicated for $2.5 million. Now, Ryan's magic touch has struck again.

Caveat, a colt he bred and owns in partnership with two friends, is one of the favorites to win Saturday's Kentucky Derby. If Caveat succeeds, he will join Kauai King and the disqualified Dancer's Image as the only Maryland-bred winners of America's most famous race.

Ryan has been interested in horses ever since he was a boy growing up in Pittsburgh, but for most of his adult life he had to concentrate on his home-building businesses: Ryan Homes and Ryland Homes, which built many of the residences in Columbia, Md. When Ryland went public, Ryan said, "I had some money then," and he decided to buy some thoroughbreds.

His brother advised him, "Make your mistakes on inexpensive horses," and Ryan heeded this wisdom by starting at Charles Town. When his first trainer, Bobby Hilton, asked him what his plans were in the business, Ryan said, "I'd like to take a shot at winning the Triple Crown races." That might have seemed a fanciful notion for the owner of cheap, rock-bottom claiming horses, but no one is laughing at Ryan's ambitions now.

After learning the basics at Charles Town, Ryan bought his farm and then went to a sale in Kentucky to buy a mare. "The one I wanted to buy went too high," he said. "We went outside, and my former wife, Eleanor, noticed a mare in the paddock. We went back in and bought her for $36,000."

The mare's name was Smartaire. She produced a foal, Quadratic, who won more than $200,000, and then produced Smarten, who earned more than $600,000. Neophytes aren't supposed to get that lucky in what can be a cutthroat business, but Ryan was just beginning. Sight unseen, on the recommendation of a bloodstock agent, he bought another mare and her weanling filly. That filly, Cold Hearted, won a stake, was retired and then produced a foal to be named Caveat.

For much of his career, Caveat has been one of those frustrating animals who habitually comes from far behind and just misses. But in the Derby Trial Stakes here last Saturday, he came from far back--from last in a field of 14, in fact--and nailed the leaders at the wire. "He is really blooming at the right time," said trainer Woody Stephens. "I'm hoping he'll put in just as big a run at a mile and a quarter."

If Caveat does that, Ryan may realize the greatest dream of every American breeder. graphics/photo: Caveat is the object of tender loving care after morning workout at Churchill Downs to prepare for Derby. AP