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Competitive Agricultural Systems in Global Economy
Predicting Fertility of Bulls
Issue
Fertility in a livestock enterprise is 5 to 10 times more important
economically than any other production measure. Bulls with identical
semen quality in terms of physical assessment vary in actual fertility.
Means to identify bulls on the basis of fertility potential could result
in higher pregnancy rates, leading to larger calf crops.
What has been done?
University of Arizona animal scientists assisted in developing a color-based
diagnostic test to identify a protein on bull sperm. An antibody is
used to detect presence or absence of that protein which is referred
to as fertility associated antigen (FAA). Bulls with FAA on their sperm
are 17 percent more fertile than herdmates lacking FAA over a 60-day
breeding season. Heifers inseminated once to bulls with sperm-associated
FAA had a 16 percent higher pregnancy rate than herdmates inseminated
to bulls without FAA on their sperm.
Impact
A 1 percent increase in fertility in the U.S. beef industry would return
a net profit of $55-60 million to U.S. producers. Obviously, on a global
scale, billions of dollars of income could result from identifying higher
fertility bulls and males of other livestock species.
The King Ranch in Texas used high fertility bulls in their nucleus
breeding herd for eight years and retained daughters of those bulls
as mothers in the nucleus herd. They were bred to high fertility bulls
each year. The payoff was clear in 1998, when 83 percent of the calves
were born in the first 30 days of the calving season. This resulted
in significantly more beef weaned and marketed per cow, which is a direct
measure of profit.
The diagnostic test was released for commercial use in 1998, licensed
for any rancher or veterinarian in the world to use. Since then it has
been adopted by breeders across the U.S., and in at least a dozen countries
worldwide, in the Pacific Rim, South America, Canada and Europe.
Funding
Hatch Act, National Research Initiative
Local: Sire Power, Inc. and King Ranch
Contact
Roy L. Ax, professor
Department of Animal Sciences
P.O. Box 210038
The University of Arizona
Tucson, AZ 85721-0038
Tel: (520) 621-7622, FAX: (520) 621-9435
Email: royax@ag.arizona.edu
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