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Bovagene Update • July 2014

Excerpts from "Maternal Myths" by Miranda Reiman, Certified Angus Beef LLC

Some in the beef industry say that the popular urban legend in the Angus breed is that marbling potential and maternal function can't exist in the same herd. There are no facts to back that up. Yet the long-held suspicion that cows can't do it all is spread by registered producers as often as it is heard among commercial cattlemen. People have created this theory mainly because they haven't ever selected for carcass traits, so they try to characterize their herd as 'maternal'.

A new research paper, "Selection for Marbling and the Impact on Maternal Traits," explores the topic, citing nearly 70 sources on everything from heifer pregnancy and calving ease to milk production and maternal size. It is available at www.cabpartners.com/news/research.php.

Virginia Tech Extension animal scientist Scott Greiner and graduate student Jason Smith combed through academic literature and the Association's Fall 2013 Sire Summary to help answer the question: Has marbling selection affected cow herd productivity? In a nutshell, what we've found is that, no, it has not. Marbling has a very small, if not insignificant, relationship with most of the traits that we associate with cow herd productivity.

The first step to building a productive cow is to get her bred and bred early. Scrotal circumference is considered an indicator of fertility, both in bulls and their daughters. Early on, there were a couple of fairly high-marbling bulls that also happened to be low-scrotal-circumference bulls, and automatically there was this association that marbling and scrotal circumference had this big negative relationship, but that is not the case. Both small-scale studies and actual analysis of the expected progeny differences (EPDs) for marbling and scrotal circumference found no association between the two traits. The paper also confirms that a marbling focus will not affect age of puberty.

Ultrasound evaluation of heifers that settled in a single-service artificial insemination (AI) program had higher intramuscular fat compared to those that did not get bred in the first cycle. There is no correlation between marbling and heifer pregnancy in the Angus database.

The research is limited, but what exists doesn't expose any negative associations between marbling and calving. Instead, several findings highlight possible positive impacts, such as increasing marbling in tandem with calf survival, lower birth weight and better calving ease. This is always important, whether you're selecting for marbling or not: keeping milk production at a level that's appropriate for your environment and your management. For now, the Association's data provides the best picture, showing that there is a positive correlation of 0.22 between marbling and maternal milk EPDs.

The scientists found no evidence of increased calving interval or reduced stayability among high-marbling populations. Indeed, the average marbling EPD of the 25 top-use AI sires has dropped.

It is a seedstock producer's responsibility to stay focused on marbling. Five to 10 years from now, the surviving feedyards will know where the cattle are coming from. If we've taken our foot off the pedal, we're setting our customers up for failure.

The paper finds no significant link between marbling docility and EPDs. The marbling EPD is positively correlated with the residual average daily gain (RADG) measure and the Angus weaned calf dollar value index ($W), suggesting a favorable relationship between marbling potential and both preweaning value and postweaning gain efficiency, it says.

Using EPDs and indexes to match cattle to environment is key.

Colorado State University meat scientist Dale Woerner says, "Flavor has replaced tenderness as the key driver of beef consumption today. Never lose sight of the fact that marbling is the key driver of flavor; don't weak on your marbling focus."

"Through the use of genomics and science, moving forward we're going to be able to understand these relationships much better," Greiner says.

The Angus breed has been known for both its maternal and carcass merits since the cattle arrived in the United States 135 years ago. That said, I don't like to live relying on tradition or history, so we now have a very complex, expansive database that will allow genetic progress to be made for these traits with great reliability. Backed by facts, of course.

Ben Lawson