It’s that time of year for breed associations to have their spring National Cattle Evaluation (NCE) run to produce expected progeny differences (EPDs) for a release somewhere around the first of the year. The quality of these EPDs is directly related to the quality of data that is used to produce them. Each breed has different approaches to assuring quality or lack of quality.
Ultimate quality is obtained when all producers submit all of their data. Procedures do this under many names within the breed associations, but the oldest and most common are Whole Herd Reporting or Total Herd Reporting (THR). Mandatory THR has many advantages over voluntary reporting, but the primary ones are complete reporting of weaning weights, ability to implement strict data filter to remove data that should not be in the analysis, and collection of reproductive data.
The reporting of complete weaning weight data is the single most important item to assure calculation of reliable EPDs. This is because it is a correlated trait to most of the EPDs calculated in NCE. Weaning weight contemporary group information is also used to account for selection of other traits such as yearling weight. If weaning weight data is biased, the reliability of the whole NCE is questionable. For example, it is an easy calculation to give credit that the animals selected to grow through yearlings are better than average, even though the bottom end was culled at weaning. Reporting only the best animals at weaning results in lower than expected EPDs for all traits correlated with weaning weight, which again is most of the traits. For those animals not reported, the animals in their pedigree will have inflated EPDs. It is a vicious cycle that compounds over the years.
Data filters to remove data that should not belong in NCE are also greatly enhanced with mandatory THR. Unlike selective reporting, with THR accounting for all contemporary group weights through weaning, a normal biological distribution of the data occurs. Therefore, with very simple statistical formulas, data can be removed that has an infinitesimal chance of occurring in nature. With a reasonable number of these filters, a single animal or whole contemporary group can be flagged for removal. Examples would include contemporary groups that people guess the weights on, or single animals that have had favorable treatment such as a show cattle, or unfavorable such as a sickly calf. It generally comes down to either too much or too little variation in the weight(s) to have occurred in nature where all animals have been treated the same and then actually weighed with scales. Even without THR, the very few people who make up data should know that over the long term, it will always catch up to them when they sell animals that don’t perform as advertised.
The last major benefit of THR reporting is that reproductive data is collected.
Reproduction has been reported to be from two to 10 times more economically important than growth and carcass traits. Therefore, it is imperative that breed associations calculate reproductive EPDs such as heifer pregnancy and stayability/longevity. With an inventory-based system, that THR represents, heifer exposure and pregnancy data can easily be collected as well as reproductive status of cows. This data allows EPDs to be calculated for the critically important traits stated above. However, it is critical in a THR system that associations enforce reporting rules with heavy penalties, such as inactivation of non-reported cows, if a producer does not report the reproductive status of a cow(s). Without stiff reporting requirements, the reproductive data collected by an association is of little use because it will be biased by producers who do not report on open cows or cows with dead calves. Unfortunately, some breed associations do not follow through with this critical step of enforcement that is needed to collect unbiased reproductive data.
Very few breed associations, like Red Angus, have mandatory reporting that is enforced. Many more have voluntary programs. Voluntary programs work well for collecting reproductive data, but do not necessarily fulfill the goal of collecting unbiased growth traits. This is because one herd that is participating in THR may report all the data, but a neighbor using the same A.I. sires may be reporting selective, biased data. This means the EPDs of these A.I. sires’ EPDs are still calculated with biased data. It is even more important with reproductive traits, and in reality, only data from an inventorybased system should be used to calculate truly useful female reproductive EPDs.
When you go to buy bulls this winter or spring, it is a fair question to ask a purebred producer how they report data. After all, the reliability of the EPDs you are selecting cattle on depends on the reporting practices of your seedstock supplier! — Dr. Bob Hough [Dr. Bob Hough has served as the executive vice president of the Red Angus Association of American and more recently as executive vice president of the North American Limousin Foundation from 2009 to early 2011. He is now a consultant, freelance writer and semiretired.]