Competitive Agricultural Systems in a 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?

A color-based diagnostic test was developed 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% more fertile than herdmates lacking FAA over a 60-day breeding season. Heifers inseminated once to bulls with sperm-associated FAA had a 16% higher pregnancy rate than herdmates inseminated to bulls without FAA on their sperm.

Impact

A 1% 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 has 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% 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 method has been adopted by other breeders around the world, including 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 and head, Department of Animal Sciences
The University of Arizona, P.O. Box 210038, Tucson, AZ 85721-0038
Telephone: (520) 621-7622, FAX: (520) 621-9435
Email:royax@ag.arizona.edu

This report is one of 29 impact statements submitted by the University of Arizona College of Agriculture to the USDA's 1999 CSREES Science and Education Impacts database in Washington, D.C. An impact statement is a brief summary, in lay terms, of the economic, environmental and/or social impact of a land-grant program. It states accomplishments and their payoff to society.
Located at http://ag.arizona.edu/impacts/2000/bullfertility.html
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