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Eastern NE KS | Would someone tell me why nobody talks about accuracy of the EPD? Instead, over and over I read negative comments about EPDs. Using EPD values without assessing accuracy is like trying to use a F450 and stock trailer to haul cattle with flat tires on both.
I get that accuracy values are seldom published in sale books. But they are published on breed association websites. Accuracy ranges from 0 to 1. In use, we see acc values as low as 0.2- to high of 0.9+. An accuracy of 0.2 means only 20% of the progeny performance difference is statistically understood. The rest is unexplained (environmental? Epigenetics?). Heavily used bulls with large number of progeny records will have their epd change to sit middle of the recorded progeny performance. Future progeny will have equal chance of performing better or poorer than the epd. Accuracy moves higher as more progeny records arrive into the tool. Understanding this, tires on the F450/trailer are at 40 pounds. You can move it slowly to the air compressor.
I know a virgin bull won't have highly accurate epd's but his sire can. If you want to change the phenotypic performance of your calves you need to add accuracy and/or parental accuracy into the assessment. If the bull's sire is highly accurate then you can make progress toward your breeding goals. You can get your tires aired up and rig ready to use.
I lived the mistake we are talking about. My dad's driving belief was every new generation is the best available. We used a lot of unproven ai sires. What he failed to fully understand phenotype improvement can be highly environmental. I was the one who was supposed to understand the epd tool but it wasn't explained in high school - on farm ratios only, wasn't fully understood in basic stats class in college and being practiced now but still learning details surrounding the tool.
I can explain more but this is getting long. And I want to know if folks are going to push back against my suggestions and how.
Edited by Doug61 12/6/2022 22:01
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Terminal vs maternal breeding
