Across Herd Genetic Evaluation

Click here to read this PDF article by site contributor Stephen Mulhollahd, Ph.D: Across Herd Genetic Evalutation: it’s important, and we’re doing it wrong.

An extract of this article is below, click on the link above for a pdf of the entire article.

When the AGE program was launched around 2003 I was very excited. I am a very big fan of proper quantitative genetics. Done right, a program like AGE can hugely speed the genetic development of a herd- it allows you to make very good and truly informed breeding decisions. We submitted data in one of the first AGE rounds.

Then, as I got to see how the AGE had been designed and implemented, my enthusiasm waned. Of late I have gotten highly critical of the AGE, and since I started expressing that criticism publicly, I was asked to write this article to explain what I think is wrong with the AGE as it now stands, and how we could do it much better.

What is the concept of the AGE? At its most fundamental level AGE is about distinguishing the genotype (the genetic makeup) of an organism from its phenotype (what it looks like). AGE should allow us to separate and quantify the genetic strengths and weakness of a male or female; how likely it is to throw a cria with improved fleece fineness, staple length, or any other measurable and heritable trait.

The AGE analyzes the traits of offspring to determine the genetic contribution of the sire and dam. In theory it should distinguish between the animals that look good but throw mediocre cria from the “gems in the rough” which don’t look exceptional and could never win a show ribbon, yet produce cria that are truly outstanding.

This is the so-called “breed value”, the strength and weaknesses of an animal in different traits. This information allows you to then pick the males and females with the best genetics, so that you can make the fastest improvements in your herd….

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