Prime_Time_summer_2019

AAA Genetic Evaluation Configuration

BY KARI WHITE, GENETIC EVALUATION SCIENTIST, NEOGEN

I n the spring of 2019, the American Akaushi Association (AAA) partnered with genetic service provider Neogen to fully update and customize the AAA ge- netic evaluation. The goal of the updated analysis is to provide American Akaushi Association breeders with reliable selection tools custom to the Akaushi population. The first step in reconfiguring the expect- ed progeny differences (EPD) analysis for AAA was making sure any calculated EPDs contained only information that would help breeders select animals that would be better parents for the next generation. Some traits are affected by things that can’t be passed down to the next generation, such as age of dam on birth weight for example. We know that older dams tend to have heavier calves than first- or second-calf heifers. It wouldn’t be helpful for a calf’s birth weight EPD to be high just because his dam is older. To correct for this issue, we adjust raw birth weights based on age of dam of the calf. One of the many benefits of working with Neogen as a genetic service provider is the potential to customize the genetic evaluation for traits that are of specific importance to AAA breeders. Traditionally, AAA has used standard data adjustments suggested by the Beef Improve- ment Federation (BIF). However, BIF guide- lines state that it is more accurate to build population-specific adjustments if enough information exists. The AAA evaluation now has custom adjustments for birth weight, weaning weight, post weaning gain and marbling. These adjustments remove the ef- fect of known non-genetic influences, such as age of dam and age at weaning, allowing for a more accurate measurement.

Figure 1. Raw birth weight relationship with age of dam

Figure 2. Adjusted birth weight relationship with age of dam

As you can see in Figure 1, raw birth weights increase as the age of dam in- creases. After being adjusted, the line be- tween birth weight and age of dam flattens out, meaning the relationship between the two has been removed (see Figure 2). This allows us to fairly compare birth weights on animals with various dam ages. Contemporary groups are important in genetic evaluation because they allow us to compare the genetic potential of 

Akaushi Prime Time • Summer 2019

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