Marty Williamson has 105 bulls and maintains one bull for every 20 to 25 cows. He doesn't keep a bull longer than five years, so he buys 20-25 replacements each year. Most of them are yearling bulls.

That's been unusual on California's rangelands, which are often harsh and hard on bulls. But the situation is gradually changing. Yearling bulls are finding acceptance - for several good reasons.

Because the Boston Ranch only uses a bull until he's five years old, manager Williamson says the yearlings give the operation an extra year of service.

But there are other good reasons for using yearlings, says Mike Hall, beef cattle specialist and a professor in the Animal Science Department at California Polytechnic State University at San Luis Obispo. He's a promoter of the use of yearling bulls because of genetics.

The Freshest Genetics "Yearling bulls offer the newest genetics," Hall says of buying a yearling bull from a quality breeder who is upgrading his herd every year. "And being the newest, they should be the best genetics."

Hall explains that breeders often utilize the best genetics to have their herds show progress in the newest trends in the beef industry. This is a slow process that may take years for those genes to get into the nation's commercial cattle herds.

"We have a slow generation interval, and everything we can do to utilize that (new genetics) helps us," he points out. That's especially pertinent when you look at the national picture and realize that cattlemen are competing against poultry and hog producers who can change their animals' genetics much faster.

To further promote yearlings, Hall conducts an annual all-bull yearling sale at Cal Poly. The sale attracts bulls from breeders all over the state. The sale was changed from two-year-old bulls to yearlings in 1979.

While yearling use in other parts of the country is not so uncommon, "California has been a two-year-old bull state for many years," Hall says. After evaluating yearling bull potential for so many years, Hall is sold on their capabilities, and the potential is increasing over time.

Yearlings, he says, are getting bigger. While a 1,000-lb. yearling bull was considered large in the 1960s, a 1,300-lb. yearling is not unusual today.

Buying a tested bull gives a producer an excellent means of finding genetic traits he wants to improve in his herd. Selecting for maternal traits such as milk production and frame size, for example, can give a commercial producer great calf traits. By using yearling bulls, those traits will be the gene pool's freshest.

In addition, Hall says, performance testing such as that done at Cal Poly prior to sale gives a good prediction of progeny feedlot performance.

"This is the best time in an animal's life to measure the traits that are available today," Hall says.

Williamson agrees that genetics are important. But does he get a better bull for his money when buying them a year old?

There Is Risk "I feel I can," he says. "There's a certain risk."

The upside is that he infuses the newest genetics into his 2,000-cow herd more quickly, and gets top-notch crossbred calves. A downside is that those young bulls are unproven in the field, which is why Williamson buys only at the production sales of reputable breeders or at the Cal Poly annual sale.

Williamson estimates he saves $1,000 per bull by buying them at one year of age. The savings will vary based on breed, test results, condition, etc., but it's something to consider in ranch economics. That extra year, he says, "saves a lot on breeding cost."

But Williamson's primary reason for buying yearling bulls is herd health. It's part of his trichomoniasis prevention program.

"The younger bulls will get trich but they can flush it out better, once they're away from the cows for a while," he maintains. "Whereas an older bull will always have it - and spread it to the cows every year."

Managing for this venereal disease is a big part of Boston Ranch's total management program. Williamson relies on his Angus, Hereford and Gelbvieh yearlings not having trich when they arrive and being able to shed the organisms well for five years.

Hall agrees that disease prevention is important, which is why the bulls from Cal Poly are guaranteed as virgin bulls. "They're not going to have any venereal diseases," Hall says. "That's a big plus."

Extra Management Hall says research has shown that the best breeding bull is a two-year-old bull that has been breeding as a yearling. After a yearling has been on the ranch for a year, learning the ropes and getting range-acclimated, he will hit his peak the following year, he says.

On the other hand, yearlings require some extra management. Hall notes that yearling bulls can be harassed a lot by older bulls, may need some feed supplement their first year, and have a tendency to favor one particular cow and hence be ineffective.

Experience also indicates that twice as many yearlings may be required to cover the same number of cows that older bulls cover. All these traits require attention by the manager, though another plus is that they are not so heavy that they hurt small cows.

"You need to take care of these bulls, because they're still growing," Hall says.

Williamson agrees. When yearling bulls are brought onto the ranch they are separated from the older bulls. A single yearling may even be isolated for a while. "He'll get tortured quite a bit," Williamson says of the solitary yearling left in a pasture with old bulls.

The Boston Ranch, which runs cows at elevations ranging from 500 to 5,500 feet, feeds its yearling bulls a little hay during the breeding season. Hall says he would even recommend having them with the cows for two weeks, then separated and fed hay for two weeks as a conditioning measure before returning them to the pasture. He says a bull can lose 300 lbs. during a breeding season if not cared for properly.

"Our bulls are out 75 to 90 days," Williamson says, and it's hard on the yearlings if they don't get coddled a bit. He also tries to "match body size" of yearlings with cows, which means he will put them with three- or four-year-old cows generally.

But he also says that yearlings are no harder to condition on range than are older bulls (he also uses quite a few "spring yearlings," which are 18 months old).

"And when yearling bulls go out the second year, they really work, much more so than bulls bought at two," Williamson says. He buys about 20 bulls each year, half of them yearlings.

"When they're younger, they're easier to handle," he adds. He hasn't seen any difference in conception rate correlated with bull age, but yearlings are able to handle fewer cows.

Another Proponent Aaron Lazanoff also believes in yearling bulls. He manages the Oak Ridge Ranch in the Carmel area. He also used yearlings at his previous ranch.

"They're cheaper," Lazanoff says, "and there's more of a selection at the sales we go to."

He likes them for the same reason Williamson does. He gets an extra year of service out of yearlings, and he gets a quick infusion of good genes.

"Last year, we ran all yearling bulls," Lazanoff says. That was due to a ranch sale situation, but the results were good. "We had a 92% conception rate."

Lazanoff says he sees more ranches using young bulls. And they seem to be satisfied. "Some people say they don't last," he says. But he hasn't seen any breakdown in yearling bulls, even in very rough country. In fact, in really rough terrain he saw more health problems in the older bulls.

One drawback of young bulls is that it is harder to detect just how good they are, Lazanoff says. A small percentage of bulls he has bought "didn't look so good" after a year or so. He looks for good feet and legs, straight lines and a long stride in their walk - which tells him they should travel well. And he buys some bulls from Cal Poly, where they are well-tested.