with Dr. Steve!
by Stephen Hull, Ph.D.
EPDs -Expected Progeny Differences are an under-utilized tool, even ifnot new. The reason most people do not take advantage of EPD in their animals is because they don't understand them. It is true there are a lot of factors in getting the EPD formulated. But as an alpaca owner you do not have to know everything about EPD for your herd to benefit. SNIP
EPDs are simply estimates of an animal's breeding value. Breeding value is defined as the value of an individual animal as a parent. If you look at expected progeny differences, the word differences means comparing something. EPD take the information given in breeding values and allows you to use it to compare alpacas so you can decide which one has the better traits for your herd.
How are EPD going to help you? EPD can be used for maternal traits such as birth weight, cria weight gain (think milk production) and birthing ease. However, EPD also can be used for traits such as fleece color, density, fineness etc.
Alpaca owners should utilize EPDs by considering traits needed to improve their herds and select a stud desirable in those traits. Simple isn't it?
The reason it is so important to consider the stud is one male can breed virtually all of the dams in your herd, but one female can only contribute genetics to her offspring. This does not say to not keep your genetically superior females. But you can make a change in genetics much faster with the male. The old dairy expression is: "don't look at my cows, go eye the bull".
So the way you would use EPD, for example, would be in a scenario that your crias were too big and you ended up having dystocias resulting in a few dead crias. What you should do is find a sire that has low birth-weight EPD and use him for breeding your dams - especially the maidens. Genetically, this gives you the opportunity to have lower-weight crias in your herd and leads to fewer dystocias.
Then, select for the sire that has a low birthweight EPD, but one with a tremendous post birth weight gain. Expect small crias that grow like a weed - and many sires have these attributes.
When talking EPD though, you need to remember this is a prediction. To help your odds of the desirable genetics carrying on to your herd's offspring, you should use animals that have a high accuracy. The accuracy of EPD is based on how much data has been collected on the animal, and that is based on how many offspring it has produced. The more offspring, the higher the accuracy, and the higher the accuracy, the more likely an animal is to be a consistent sire of listed EPD.
EPD can be confusing at first, but once you have an understanding of them, they can be a great tool. EPD are most commonly used in dairy, beef and swine productions.
Stephen Hull, MS, PhD, Tom Cameron, DVM & families
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