The Animal Industry in the United States is one of the largest and most important economic sectors. Therefore, it is imperative that we understand the type of animals that are most efficient and most valuable in production. The subject of livestock evaluation is an important division of animal husbandry and is related, in a most vital way, to the other major divisions of feeding and breeding. In any program whose purpose is to recognize an appreciation of improved livestock, successful methods of production and marketing should warrant special attention. Success in the production of livestock depends, in a large measure, on the ability to see merit in breeding animals; and to understand values when buying and selling. The ability to evaluate is a cornerstone in the success of all aspects of livestock production.
One of the most powerful tools a breeder of livestock possesses is selection. Selection is defined as a means of appraising an animal’s value for the purpose in which they are produced and improving upon that value in the next generation. Preventing inferior animals from reproducing and allowing the superior animals in the current generation to become parents of the next generation should help increase the proportion of genes having the desired effect on traits of economic importance. Consequently, the ability to identify potential seedstock with excellent genetic merit is essential to livestock breeders. The use of Expected Progeny Differences (EPD’S) has improved our means of evaluating an animal’s genetic value as a parent. Therefore, understanding the proper use of these tools and some fundamental concepts is very important for success in selection programs.
The basic concept of genetic prediction, the use of EPD’s, is more valuable than individual performance records, within herd ratios or performance tests because all of these pieces of information along with heritability values are taken in consideration when calculating an estimated breeding value (EBV) of an animal. Then, because we all know that progeny will inherit ½ genetic material from each parent, EPD=1/2 EBV. The concept of an EPD is very easy to understand from here because it is truly the expected difference in performance between progeny.
Bull A has a Yearling Weight EPD of 75
Bull B has a Yearling Weight EPD of 95
When mated to similar cows, you should expect calves sired by Bull B to weigh approximately 20 pounds more on average as yearlings than calves sired by Bull A. This could mean B’s calves would average 950 pounds while A’s calves would average 930 pounds. This may not sound significant, but Bull B could potentially sire close to 2,000 more pounds of beef than bull A over three years and the price of cattle at this point makes him much more valuable.