Accuracy Matters...
Not all Carcass EPDs are Created Equal Mushrush Red Angus invests tremendous resources to ensure the EPDs we publish describe our cattle as accurately as possible. Our Commitment to “All the Data, All the Time” goes far beyond collection of typical data points such as birth, weaning and yearling weights to include calving ease scores, cow weights with body condition scores, heifer pregnancy observations, carcass ultrasound scans, stayability observations, udder scores and gain and feed conversion. Still, there are some economically relevant traits for which data collection at a seedstock operation ranges from difficult to impossible specifically, carcass data. That may come as a surprise to many; after all we’ve seen those REA (Rib Eye Area) and IMF (% intramuscular fat) ratios in bull sale catalogs for 20 years. It’s true many seedstock producers – ourselves included, hire ultrasound technicians to measure differences in %IMF, REA and backfat of our yearling seedstock cattle. That data is submitted directly from the ultrasound lab to the breed association, and the within contemporary group variation observed on our ranches influences the Marbling, Ribeye, BackFat and Yield Grade EPDs of our cattle. However, an ultrasound scan on a yearling bull or heifer on a growing or forage ration is a different trait than actual harvest data collected at a slaughter plant on finished steers. Ultrasound data and harvest data are different traits but fairly highly correlated. Still, ultrasound ribeye explains only about 40% of the genetic variation in ribeye area. Thus, as we collect increasing amounts of ultrasound ribeye scans on a bull’s progeny we have a hard time ever moving beyond accuracies in the 40% range. Well if ultrasound won’t get us the reliability we want perhaps we’d be able to feed our cull bulls to harvest and collect their carcass measurements. That makes sense – at Mushrush Red Angus we sell about 200 bulls a year out of nearly 1000 breeding age females – so there must be plenty of extra bulls to feed for carcass data? Not so fast…perhaps someone remembers reading in prior Mushrush Newsletters about the importance of well-formed, equal-opportunity contemporary groups in terms of data accuracy? If we collect carcass data on only the “cull” bulls, then we are subjecting our data to selection bias. It would create the same problem as only reporting birthweights on calves that weighted less than 80 lbs., or weaning weights for the heaviest half of the calf crop. Anytime we don’t report the entire contemporary group we artificially reduce variation by removing a significant portion of that population from the dataset. Bottom line is the only current way to “prove” sires to a high level of accuracy for carcass traits is through the collection of actual carcass measures taken from sire-identified animals at harvest. For several years, we have been working in cooperative efforts with progressive commercial cow herds and feedlots to plan and execute structured progeny tests. In these tests, upcoming (low-accuracy) sires are tested against proven carcass sires in matings that are randomized across breed and age of the commercial cows. This reduces any bias that could occur from one sire being bred to an “unfair” set of cows. Calves are born and remain in their birth and weaning contemporary groups all the way to harvest. Weights and measures are taken within these contemporary groups and the data is submitted to the respective breed associations for inclusion in Red Angus’ National Cattle Evaluation. Whenever you see a sire like Mushrush Lock N Load U213 with a Marbling EPD accuracy over .60 – you can rest assured he earned that accuracy through actual carcass data.
2016 Progeny Test Results:
The matings we made in this structured progeny test in the spring of 2015 were born in 2016 and harvested in 2017. For a herd that focuses on fertility, longevity and calving ease, we were very pleased with the group data our bulls produced for the test herd: • ADG: 3.89 • Feed Conversion: 5.49 • YG = 3.13 with 29% YG 1’s & 2’s • 90% Choice with 48% Premium Products (higher Choice or Prime)
How much variation exists between sires?
Table 1 (below) demonstrates the average and variation by sire group of the 2016 born progeny test calf crop. As you can see total variation ranged from a low of 17% for Hot Carcass Wt. to 57% for USDA Yield Grade. Table 1: HCW (hot carcass wt) REA (in2) USDA Marbling Score USDA Yield Grade (YG) Avg of all Sires
806.5
13.5
519.6
3.13
Best Sire for Trait
829 (3% above Avg.)
16.3 (21% above Avg.)
607 (17% above Avg.)
2.0 (37% above Avg.)
Least Sire for Trait
695 (14% below Avg.)
11.4 (15% below Avg.)
455 (12% below Avg.)
3.8 (20% below Avg.)