SPRING 2011
Our Passion YOUR SUCCESS
DNA Technology for Seedstock Producers by Jennifer Minick Bormann, Ph.D., Kansas State University We are in the midst of the most exciting is very close to his actual genetic merit. If there is less information time in beef genetics since development available on a bull, the EPD is still our best estimate of his genetic of EPD 30 years ago. Information directly merit, but we are less confident that it is very close to actual genetfrom DNA has long held potential to revoic merit. That is reflected in a lower accuracy value. High accuracy lutionize cattle breeding, but only recently EPD is the gold standard predictor of genetic merit. There is no incorporated to influence selection decibetter way to know what progeny a bull will produce. sions on a large scale. The biggest limitation to getting high accuracy EPD is number of To understand the contribution of progeny needed. Depending on trait, this can be costly. If you have genomics information, scales, cost of collecting birth or weanunderstand that aniweights may be negligible. However, High accuracy EPD is the gold standard ing mal data (birth weight, marbling score, scrotal some data (carcass, ultrasound, feed predictor of genetic merit. There is no intake) is very expensive. circumference, etc.) is made of two main components: genotype and environment (Figure 1). better way to know what progeny a bull From a genetic improvement standSome of what makes an animal good or bad for a point, time lag is also costly. It takes will produce. given trait is due to genetics and some is due to many years to get high accuracy EPD, environment. The environmental portion is not slowing the rate of genetic improvepassed on, so our goal is to determine how much of an animal’s ment. The billion dollar question of developing DNA technology ‘goodness’ or ‘badness’ for a trait is due to genotype. As breeders, is: Can we bypass the time and expense of collecting a lot of data we really only care about the silver part of the chart in Figure 1. and go directly to the DNA to learn about genetic merit? Unfortunately, we can never know an animal’s exact genotype. Early efforts to use DNA in beef cattle selection involved tests We estimate based on all the data available. The EPD is our best for one or two genes. The amount of genetic variation explained estimate of genotype, based on performance data collected on the by the gene test is represented by the red circle in Figure 1. The animal itself, as well as on pedigree and progeny. The accuracy of first generation of genetic tests explained very little of an animal’s the EPD is determined by the amount and type of data available. genetic merit for the trait. Whether an animal had the correct genIf there are hundreds of progeny records on a bull, his EPD will otype for a trait as determined by the gene test had very little to be highly accurate. In other words, we are confident that his EPD do with his overall genetic merit for that trait (which is predicted
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