Angus Single Step- Thumbs up or down?
On everyone's mind and some cattleman's tongues is the new testing set forth by the American Angus Association. There were definitely some big changes for some animals while others stayed relatively the same. What's going on here? To understand what changed, it would be easier to explain what it was before. A multi-step inclusion of genomics has been the norm for beef seed stock associations. This is simply running the pedigree and phenotypes first and then blending the genomics in separately. With the limited number of genotypes (DNA samples) available this was the best method at the time. Now, genotypes have built up to a point that a new system was needed in order to make the data even more relevant and accurate. To make a simpler system that works faster and more effectively they went from multi-step to single-step. I know that is simplistic, but that is all they did in a nutshell.
With normal pedigree Expected Progeny Differences (E.P.D.) estimates the assumption is progeny inherit 50% of their DNA from each of their parents. In reality, it isn't so cut and dry. Single step gives us a better starting point on pedigree E.P.D.'s. This is because they tell us approximately how many DNA markers progeny inherited from each parent. As an example, if the sire of a calf has a birth weight E.P.D. of 2.0 and the dam is a 0 then without DNA and actual data the calf would be a 1.0. If we DNA tested this calf and he inherited more DNA from his sire then we could call this calf more like a 1.5 for his birth weight E.P.D. Then his actual records are submitted and he ratios 108 for birth. This would take him clear out of heifer bull contention. This is important because had we still relied on the 50% model he could be called a "borderline" heifer bull.
They also made some changes to the formulas. From a big picture view, strides were made in carcass reporting by including weaning weight (to off set selection bias) and the inclusion of back fat for carcass composition. AAA also made Dry Matter Intake a larger part of the $B index. Another advantage of the new system is accepting birth weight observations by themselves without waiting for weaning weight data. Which basically means we can get more accurate data on young sires earlier in the breeding season. This should be of particular interest to anyone trying to sell semen on their herd sires.
All of the above information is already known. What is of particular interest to me is how Angus producers are reacting to it. I have heard everything from Chicken Little's the sky is falling scenarios to non-stop praise. Personally, I think this is a step in the right direction. The data really does fit the cattle better and for the first time in a long time, I can look at the cattle then look at the paper and it makes "sense." Certainly, it's not perfect, but it's a big step on the road to higher accuracy cattle breeding. Cattle, of all species, has the most to lose with inaccurate data. Our production cycle is simply too long to make a bunch of mistakes that could have been avoided. Although the dairy industry feels a world apart from the beef world, I look to see what they are doing for any relevancy and application. In this case, the single-step was implemented by them first and they have been enjoying the benefits for a much longer time. I saw recently where the U.S. Dairy industry has hit the 2 million mark for genotypes. Angus is over 300,000. The not so trivial difference means a DNA test in the dairy world yields incredibly higher accuracy than in an angus animal today. What dairymen can tell about a day old heifer's lifetime production with tremendous accuracy is simultaneously exciting and a little scary. As with all things- time will tell. This is what we do know: single trait selecting will bury a person faster than Hillary Clinton on election night. You cannot only select on single traits like; big hipped cattle, good feet, big bellies, high $B, low BW, etc. It's all about a combination of traits, emphasizing certain ones given your particular operation. It does matter how you select cattle. This new system should make E.P.D.'s more accurate which means fewer "surprises". It is important to breed with the big picture in mind and utilize as many tools as possible to make your breeding decisions.
Whether you use A.I. or a loaded bull battery, it is worth taking the time to get to know this new system. If you have any questions on how to apply this to your operation, please contact me at firstname.lastname@example.org or give me a call at 402-310-5056.