Beef Sire Selection Tool: Selection Index

(Bob) So, one of the things that we’ve been talking at the Winter Ranch Management Series this year is giving producers a bit of an update on some of the new Beef Sire Selection tools that are available. And we use it a little bit loosely, but two of the concepts that I’ve been talking about this year are Selection Index, so a method of weighting individual animals EPDs by economic weight toward a specific end point, as a tool for producers to use a single value then as the result of that mathematics. And using that single value in their selection decisions. We’ll talk about that more in just a minute. The other concept that we’ve been working on this year is arguably maybe a more recent addition to our suite of tools and that’s the use of genomics. And using DNA markers as a way to gather information about an individual animal’s potential for a variety of traits and then incorporating that into the EPD system that produces genetic evaluations for animals from a number of breeds here in the U.S. Kind of back to the Selection Index concept. One of the things that’s really important for producers to recognize is that for their specific operation, their set of economic relevant traits are ones that either have a direct cost associated with them in their production system, or a revenue stream associated with them. So, a common one to think about is if you sell calves at weaning time, weaning weight is an economically relevant trait. And it’s one of the traits that we have available for measuring or reporting genetic potential for growth in our production system. Other measurements for growth rate include yearling weight or post weaning gain, average daily gain, carcass weight. We could think about mature weight. Any of those other measurements of growth. And they happen to be what we call indicator traits because they in that particular production scenario where we sell calves at weaning weight, or at weaning time, don’t have a direct revenue associated with them. Weaning weight does. The other ones are indicator traits and they’re genetically associated with weaning weight. So, what we do then in a selection index is we put economic weights on traits like weaning weight, when we have that end point, and other traits that are related to production costs say calving needs, birth weight, maybe milk EPD the cow, those sort of things that have a consequence in terms of the profit equation, relative to the weaning end point. So, one of these measurements is $W, that’s produced by American Angus, a number of other breeds Simmental, Gelbvieh, Limousin, Charolais, Hereford all have a selection index as well. And almost all of them are targeted toward some specific set of end points. If you saw calves at weaning time, there’s a weaning selection index. Many breeds also have what’s called an all purpose index or something that’s related to that that says, we’re going to have a production system where we retain ownership of calves, put ’em through the feedyards so there’s emphasis on carcass traits as ERTs, but also keep replacement heifers. So, there’s an economic weighting on maternal traits as well. The nice thing about all these selection indexes is they provide a single value to use in the selection criteria eval, so instead of opening the sale catalog and trying to sort through 15 or 16 different EPDs, you can go to a single Selection Index that summarizes an appropriate weights each of those individual traits as they contribute to the profitability for that particular endpoint. So, one of the key things that I hope producers take away from our talks this year is that it’s really important then, since the index is so driven by marketing endpoint that you actually pick the right endpoint to use in selection. A common mistake is for producers to use one of the terminal indexes that only weights growth and carcass merit of animals, so we’re making an assumption all steers and heifers are going to slaughter. And they use that Selection Index in a system that is not a terminal system. So they actually keep replacement heifers back or they sell calves at weaning endpoint, so you have a disconnect between the traits that are in the Selection Index and the ones that are actually important in the selection scenario. And that creates a lot of problems in the selection system and you decrease efficiency pretty dramatically. And it’s easy to see if you don’t put any economic weight on maternal traits because you used a terminal index and you actually keep replacement heifers that you’ve actually selected, replacement heifers that potentially aren’t very good replacements because you haven’t put any weight on the maternal traits. So, a pretty kind of common sense approach that we try and advocate is that producers make sure that they align the selection index that they’re using with their particular scenario and marketing endpoint. So, it provides a really nice way to do that. One of the great things is that the scale that animals are measured on is in dollars difference per progeny in terms of profit expectation. So, it’s in dollar units and that’s an easy thing for all of us to understand and translate, so it’s a really convenient tool. And after the break we’ll talk some more about beef genomics and the use of genomic tools in beef sire selection. One of the other things that we hope producers do is that if you’re going to use Selection Index that you actually use it pretty much exclusively as your selection criteria. If you have a weaning endpoint use $W and also put selection pressure on weaning weight, now you’ve messed up your index because you’ve double counted weaning weight in your selection criteria. So, try and withhold using other tools or EPDs in selection when using Selection Index. One notable exception might be if you’re using a particular sire to mate yearling heifers for their first calf we might put some kind of criteria on say calving ease EPD as a way to make sure that we have adequate levels of calving ease performance to minimize dystocia. And the way you would do that is sort ’em up on the index that you’re using and then go find the first bull in that list that meets your threshold of criteria for calving ease. Then you’ve sort of done the maximal job of selecting for adequate calving ease and economic weighting for the traits of your marketing endpoint and interest. Selection Index is a really useful tool. It’s been around for a long time. In pork and poultry businesses primarily since the 1940s and 1950s, but not adopted in the beef sector until the early 2000s. So we’ve got a big gap in time to really prove out the technology in other species. And it’s becoming pretty widely adopted as a tool for commercial producers now in the beef sector.

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