A bull is a significant investment for any operation, and that bull’s ability to be a fertile and active breeder is critical. Bruce Carpenter, Texas Cooperative Extension livestock specialist, says the “Repro Test,” recently demonstrated at Texas A&M’s Beef Cattle Short Course, may help cattlemen identify fertile bulls.

“The Repro Test detects a protein in bull semen called fertility associated antigen, or FAA,” Dr. Carpenter says. All else being equal (semen quality, healthy bulls, etc.), FAA-positive bulls are 16 percent to 19 percent more fertile than those testing negative for the protein, according to research. “FAA-positive bulls settle more cows and they do it earlier in the breeding season. The benefit of FAA-positive bulls even helps with artificially bred females, because research has shown they require fewer services to become pregnant.”

This new test uses a lateral-flow cassette, which looks like a home pregnancy test. “Cassettes cost about $30 each,” points out Dr. Carpenter, “but a bull only needs to be tested once for FAA in his lifetime (after puberty). The trait is believed to be moderately heritable in male offspring.”

He cautions that the test does not eliminate the need for annual bull exams and fertility tests but it does add accuracy to the conventional breeding soundness exam.

“The FAA test is not a cure-all,” he says. “There are many factors that can and do affect a bull’s fertility. Breeding soundness exams, while not perfect, are still the best way to predict an individual’s fertility. Exams should be done each year before breeding season. Annual exams are necessary because things like semen quality can change, or a bull may get sick or injured, compromising his breeding potential.”

For more information on the Repro Test, go to www.reprotec.us