NEW TEST HELPS IDENTIFY FERTILE BULLS
Writer: Steve Byrns, (325) 653-4576,
[email protected]
Contact: Dr. Bruce Carpenter, (432) 336-8585,
[email protected]
FORT STOCKTON -- It's been said that "a bull is half the calf crop" In reality, that varies a lot more than many realize, said a livestock specialist with Texas Cooperative Extension.
A bull that is a fertile and active breeder may sire 80 or more calves in a season, whereas a less fertile bull will sire only a few or even none, said Dr. Bruce Carpenter. A good bull offers genetic merit, but fertility is paramount to getting those genes into the herd.
Carpenter, who is based at Fort Stockton, said the need becomes even greater in single-sire herds where the fate of an entire calf crop from 25 or more cows may depend on only one bull.
He said the "Repro Test," recently demonstrated at Texas A&M's Beef Cattle Short-Course in College Station, may help worried cattlemen get a bit more sleep.
"The Repro Test detects a protein in bull semen called 'fertility associated antigen' or FAA," said Carpenter. "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.
"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."
Until this year, Carpenter said, the fertility antigen test was tedious and required a three-day laboratory procedure. The Repro Test, however, can be conducted "chute-side" with results being ready within 20 minutes.
"The new test uses a lateral flow cassette, which looks like a home pregnancy test," said Carpenter. "Cassettes cost about $30 each, 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."
The test does not eliminate the need for annual bull exams and fertility tests, he said, but it does add accuracy to the conventional breeding soundness exam.
"The FAA test is not a cure-all," said Carpenter. "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."
According to Carpenter, the fertility associated antigen, formerly called heparin binding protein, was identified 15 years ago at the University of Arizona by Dr. Roy Ax.
"His lab did all the early basic research, literally at the molecular level," Carpenter said. "When it came time to evaluate live breeding animals, much of that research was conducted on Texas ranches. Texas A&M scientists collaborated with Dr. Ax's lab to conduct some of the large-scale breeding trials necessary to prove the test's effectiveness.
"To-date, 600 bulls and 15,000 cows have been evaluated.. Their research findings leave little doubt about the desirable qualities of FAA positive bulls."
For more information contact an Extension office or visit
http://www.reprotec.us
