Management topics

Jul 22, 2011

Time for fall genetic analysis

June is the time of the year when most breed associations run the second of their biannual genetic analyses, and although the expected progeny differences (EPDs) are released mid to late summer, the analysis is typically referred to as the fall run.

Many people believe the new data for this genetic analysis is almost exclusively from yearling data from the previous spring’s calf crop as well as some birth weights (BW) and weaning weights (WW) data from fall calves. However, people are often surprised at the amount of new BW and WW data from the 2010 spring calf crop that is included in the analysis. Breeds run on a tight schedule in the fall with firm, generally early-fall cutoff dates to submit data for the spring (early winter) analysis. Many producers simply do not get their data in time for the cutoff, so it is my experience that, in some breeds, as much as 25 to 30 percent of the new BW and WW comes in for the fall analysis. It is also surprising that a relatively low percentage of BW and WW data from fall calves are turned in time for the fall analysis, as people tend to wean fall calves later than spring calves. The bottom line is that between the year ling data and extra BW and WW data, there is much to be learned from the fall analysis.

Now, let’s consider some pointers on EPDs from the various breeds. First and foremost, you need to understand that EPDs are for in-breed use only and should not be used to compare breeds without major adjustments that would serve as a long article in itself. Given that EPDs should only be used within the breed, use common sense when viewing EPDs and breed strengths and weaknesses. For instance, most everyone knows the average Angus is high marbling, Bos Indicus-influenced breeds are heat tolerant, Charolais is high growth, Gelbvieh is high milk, Limousin is heavy muscled, and the list goes on. Any honest person familiar with a breed can give you a breed’s strengths and weaknesses, which will help you put that breed’s EPDs in perspective. Also remember that it is said that there is as much variation within a breed as between breeds, so stereotypes do not always hold up.

To put an animal’s EPDs in perspective, the best tool is the percentile chart. This shows how an EPD for any trait ranks within a breed on a percentage basis. For instance, you could look at the non-parent chart (those cattle 2 years old or younger), and see if a BW EPD for an individual of a certain breed is the 50th percentile (average), 5th percentile (very good), or 95th percentile (poor for that breed). These are listed for every trait.

In most all the entities that do genetic analysis, they run data through some type of data filters prior to doing the genetic analysis to remove data that has “non-heritable” properties. These filters can range from fairly superficial to quite rigorous. The more rigorous systems can be built for breeds that have adopted mandatory whole herd reporting because the data received by a breeder will have a normal biological distribution, while partially reported data by definition is biased.

The other item people also wonder about is how hybrid animals are handled in the multi-breed genetic analysis many breeds have adopted. Hybrid animals have heterosis, which is defined as the average advantage of a crossbred individual over the average of its purebred parental breeds. To do a multi-breed genetic analysis, these effects of heterosis must be removed from the model because they are not heritable. Although there are benefits from using a hybrid bull, genetically, you will get the same amount of heterosis if you use a purebred bull on a crossbred cow.

Many people think hybrid cattle have a built in advantage in a genetic analysis because of their increased performance due to heterosis, but this is simply not true since the extra performance due to heterosis is removed.

Next, you obviously need to know where to find the new EPDs. A breed’s website is the best place to find the new EPDs and when they will be released. If you are not familiar with how to access a particular breed’s website, the National Pedigree Livestock Council website (www.nlpc. net) has most of the breed websites listed, in addition to contact information. It is a handy guide if you want to call a breed for more information on their EPDs. The trouble is, there are fewer and fewer breed associations with trained geneticists on their staff. I personally find this to be an amazing prioritization of resources since breed associations are in the genetics business.

Many people do not pay much attention to this fall genetic analysis, but it can provide a wealth of information. I urge all serious breeders to take advantage of this new information.

To stay profitable, keep up to date and use all the objective information available to you. — 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 semi-retired.]