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counts) are applied to Qual- ity Grades. Birth weight is another great example of an in- dicator trait. Many com- mercial bull buyers select to decrease birth weight in an attempt to reduce the prevalence of dystocia. However, birth weight does not have a direct revenue

source or cost associated with it. The trait that does have a cost associated with it is calving ease (or diffi- culty). Although the two are related, the genetic correla- tion between calving ease and birth weight is only between -0.6 and -0.8, sug- gesting that birth weight only explains 36-64 percent of the genetic differences between animals for calving difficulty. Bio-economic Index Values An economic index is a collection of EPDs weighted by their economic value such that traits with greater impacts on profitability have a larger economic weight associated with them. The basic equation of an economic index is: I = EPD 1 x a 1 + EPD 2 x a 2 + EPD 3 x a 3 +… + EPD n x a n Where I is the index value; EPD n is the EPD for trait n; and a n is the eco- nomic weight associated with trait n. This basic form was first published in the early 1940s. Note that other species (e.g., swine, poultry) use indexes exclu- sively to select parent ani- mals. These tools have been available to the U.S. beef industry for close to a de- cade but have yet to reach the level of adoption that they should. How are the economic weights derived? Using historical averages of input costs and the value of sale weight and carcass premi- ums (and discounts), we use a simulated cow herd to ask the question “if all else is held constant, and 

birth weight and scrotal circumference. Ultrasonic carcass measurements are a non-destructive measure of traits, such as intramus- cular fat percentage (IMF). Producers do not receive premiums for IMF levels; rather premiums (and dis- GENETIC SELECTION PRINCIPLES Continued from page 19

Junior Page Prime Time San Jancito Winter 2019

SAN JACINTO RANCH LLC Huntsville, Texas

We have eight ¾blood Akaushi heifers that were crossed with Red Angus dams. They are 8-10months old and would be perfect for someone looking to start an Akaushi program.

We have several unique Akaushi sire bloodlines – Big Al • Heart Brand Red Emperor Shigamaru • Hikari • Tamamaru

On the dam’s side, bloodlines include – Kazutomo 1KYU 92958 • Heartbrand T0326N • Haruko • Akido • Heartbrand V7427U

Come visit us at the ranch just west of Huntsville! SJ Carolyn & Howard Davis 713-542-7777 • 713-899-4232 HBDavisJr47@gmail.com

Akaushi Prime Time • Winter 2019

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