One of the great tools we use in the beef industry is expected progeny differences (EPDs), which require performance data acquired from performance testing. Performance testing is the method of collecting data from beef seedstock under uniform conditions. Just like athletes that compete for draft spots in the NFL combine, with 40-yard dash and vertical jumps, the seedstock compete in average daily gain (ADG), feed efficiency and other measurable traits.
Performance testing sire prospects helps purebred and commercial producers make accurate breeding decisions when comparing bulls. A bull’s performance or phenotype (the physical expression of genes) is characterized by two things: genotype and environment. Genotype is the genetic makeup inherited from the sire and dam. Environment can have little effect on certain phenotypes, such as hair coat color and horned versus polled, or drastically influence the expression, or lack thereof, of certain genes and characteristics, such as ADG or feed efficiency.
When two animals of similar genetic makeup are raised in different environments, they may express their genes differently, resulting in different phenotypes. For instance, if two identical twin calves were independently backgrounded – one on bermudagrass and the other on toxic tall fescue – growth potential of the two calves is genetically identical, but performance and/or phenotype of the individuals would be drastically different. The calf raised on tall fescue would more than likely not reach its genetic potential.
This brings us back to the important point of performance testing. Bulls are tested and data is collected when bulls are managed under similar conditions in the same location. This reduces the impact of environment when it comes to explaining the differences in performance and gives a more accurate performance picture attributed to genetics. The Beef Improvement Federation and breed associations provide guidelines for performance testing and data calculations.
For female seedstock, those raised together in contemporary groups would have similar environmental effects, and phenotypic differences can be largely attributed to genetics. When attending a production sale, evaluate the genetic and phenotypic traits that would benefit your operations. Just because you might have the money to get the seedstock equivalent of the number one draft pick, make sure you prioritize your investment in animals that fill your production weak spots. 
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Matthew Burns
- Extension Beef Specialist
- Clemson University
- Email Matthew Burns
