A 40-year study to determine the best of the bulls on New Mexico's eastern plains has left its mark on the face and forelock of the state's $1.3 billion beef cattle industry, says a New Mexico State University livestock expert.

Held annually at NMSU's Agricultural Science Center at Tucumcari, the bull test and sale has drawn more than 4,500 yearling bulls from the region's top ranches. The bulls are born in the spring, weaned in the fall and shipped to the science center in October, where they're tested for 112 days.

Milton Thomas, a cattle geneticist with NMSU's Agricultural Experiment Station, says the years of data from the test paints a picture of transformation in New Mexico's cattle industry.

When the Tucumcari test started in 1961, the six- to eight-month-old bulls arrived weighing 552 pounds. In 2000, they trotted in weighing 720 pounds. At their final weigh-in just before the test ends, the numbers have soared, rising from about 800 pounds during those early years to today's 1,150 pounds.

“That's quite an increase,” Thomas said. “It's also exactly why we do these tests in the first place. We create a level playing field in which these animals can compete in a common environment so that we can compare their gainability and make genetic improvement.”

“Gainability” is another way of saying putting on weight — in this case adding pounds as quickly, economically and efficiently as possible.

“We measure a lot of traits, but gainability is really what we're after,” Thomas said. “And it's not just their size that we want, it's their efficiency.”

Efficiency is measured by the bull's average daily gain and feed-to-gain ratio. During the 40 years that the NMSU researchers have been monitoring these top specimens, average daily gain has improved from about two pounds a day to four pounds.

This weight gain is accomplished with less feed now than in the 1960s. When the Tucumcari test started, it took about 10 pounds of feed to put on a pound of gain. Now, it's about 6.6 pounds.

“We've been involved in the test since 1965, and it has proven to be a good tool for genetic selection,” said Wesley Grau, who directs purebred operations at Grau Charo-lais, a large family cattle ranch near Grady.

“Normally, we have about 12 bulls in the test. Most are sold, but we bring the top ones home for in-herd use.”

The majority of the test's yearling bulls are from New Mexico, but a few trickle in from Texas, Colorado, Oklahoma and even Kansas. Bulls are tested in these programs because that's where livestock producers can make the quickest genetic improvements from the selection intensity of one bull being bred to more than 20 cows.

Data collected from the bull test is used in several ways. It helps ranchers improve their seed stock and provides information to potential buyers who want to know the quality of animals they buy.

Of the 130 bulls normally tested in a year, about 80 are sold at the end of the testing program.

Because New Mexico's cattle have changed so much over the past 40 years, the state's cattle management practices need to change with those cattle, said Matt Garcia, who conducted a statistical analyses of the Tucumcari tests as part of his graduate research at NMSU last fall. Garcia is now earning his doctorate in beef cattle genetics at the University of Washington-Pullman.

“It's hard to select for the future, if you don't know where you've been in the past,” Garcia said “The uniqueness of this data set is that it shows how careful selection and management have improved New Mexico's beef cattle for growth and efficiency since 1961.”

Part of the reason for New Mexico's improved cattle efficiency is a nationwide trend of selecting bigger, higher-performing cattle, said Rex Kirksey, superintendent of the Tucumcari science center. “Livestock producers want calves to put on weight quickly and efficiently to reduce feed costs.”

Over four decades, bulls representing 21 different cattle breeds have been through NMSU's test, said Ron Parker, head of the animal resources department with NMSU's Cooperative Extension Service. Four breeds have dominated the Tucumcari bull test - Angus, Charolais, Hereford and Polled Hereford.

In 1961, most bulls were of the Hereford breed. But over the decades breeds like Charolais, Angus and others have increased in numbers, Parker said. “This mirrors how the entire U.S. cattle industry has changed over that period of time.”

While the bulls are getting bigger, NMSU's Thomas pointed out, birth weights have stayed remarkably steady over the years in Angus, Hereford, Charolais and Polled Hereford.

“That's good because being a range livestock state, New Mexico ranchers can't be there to help these cattle give birth.”

Tough decisions loom for the state's cattle industry, Thomas said. “We've done a very good job in the last 40 years for selecting animals for growth, but along with it we got much bigger cattle.

“The question now becomes, are we big enough, and should we be focusing on other traits?”