Management Topics

Aug 30, 2013

Crossbreed instead of using beta-agonists

With the whole Zilmax controversy shining a light on the use of beta-agonists, I think we all need to stand back and review their value to the industry. I question the real benefits of them to our industry when in my opinion crossbreeding our current British-based cowherd with Continental cattle may achieve the same results.

First to be clear, I do not question the healthfulness and wholesomeness of beef sold to consumers from cattle fed beta-agonists. With the approximately 25 lbs. of extra carcass weight gained by feeding this supplement, many people feel their use is necessary to supply current consumer beef demand. But in the big picture is the extra carcass weight gained this way worthwhile?

Although the beef from cattle fed these supplements is safe, having one in very wide use withdrawn from the market due to possible negative impact on cattle soundness is not good public relations. It made the national news and impacted the perception of our product’s wholesomeness. We simply do not need this kind of bad publicity.

Beta-agonist feed supplements are not new. When I was in graduate school over 25 years ago, several of the graduate students under my advisor were working on the value of beta-agonists. Their effect is to increase muscle mass by expanding the size of muscle fibers. This increases carcass weight and dressing percentage. The down side is their use takes away market flexibility and carcass quality is negatively impacted as well as a possible decrease in tenderness. These effects certainly do not help the perception that we are supplying consumers with the best product possible, whatever the truth.

In seems obvious to me we could increase carcass weight and feedyard growth by simply injecting high performing Continental breeds into a breeding system. The U.S. Meat Animal Research Center (MARC) data tells us the average Simmental and Charolais will grow in the feedlot comparably to the predominant breed being fed; Angus. Recent work with the Simmental, Red Angus, Gelbvieh acrossbreed national cattle evaluation shows that the U.S. MARC data probably underestimates the growth potential of Gelbvieh, and instead Gelbvieh are very comparable to Simmental in terms of growth. According to the objective data available, of the major Continental breeds, the average Limousin lags the field in terms of postweaning gain.

All the major Continental breeds (Simmental, Charolais, Gelbvieh and Limousin) demonstrate the average animal in these breeds will add considerable muscling to a crossbreeding system when compared to Angus or Red Angus. Again, a breed-average Limousin is the outlier in terms of adding an extreme amount of muscle. Crosses with extra muscling will also result in increased dressing percentage. The bottom line is that by crossing our nation’s Angus-based cow herd with some percentage of Continental blood should, in theory, make up the pound and muscle difference without the use of beta-agonist. The glory of this type of crossbreeding is the dollar cost of the feed supplement is eliminated.

So the obvious question comes up; why not feed straight Continental cattle? The reason is simple; added Continental blood will decrease quality grade, and in some instances, tenderness just like the beta-agonist. It appears that the ideal amount of Continental in a crossbreeding system is between 25 to 50 percent.

Beyond breed complementarity between British and Continental cattle, crossbreeding will also add hybrid vigor. This includes improvement in gain, vigor and disease resistance. Although hybrid vigor is not high for feedlot traits, the 2.5 percent increase in heterosis for average daily gain equals about 16 more pounds over a 160 day feeding period.

One must remember that hybrid vigor is the percent increased performance between the average of the two parent breeds. This means that high quality genetic inputs are necessary to gain performance through heterosis, i.e. garbage in, garbage out.

Because of heterosis is the average of the two breeds, not as much disease resistance is gained when crossing with Angus as one would think. U.S. MARC data indicates the average Angus has a decided genetic advantage in disease resistance over most other major breeds. This means the heterosis gained through crossing in many cases only get genetic potential of the breed crosses back to that of a straightbred Angus.

Besides the breed complementarity and heterosis advantages of a crossbred animal in the feedlot, there is also much to be gained by having a crossbred females. With the proper genetic inputs, lifetime pounds weaned per cow exposed can be increased by as much as 25 percent.

With all this said, I really question the value of the use of beta-agonists by our industry. For sure they do meet company claims of increasing carcass weight of wholesome beef, but in my opinion, our industry can get to the same end result by simply by implementing well-planned crossbreeding systems. Crossbreeding has no unintended consequences of potential bad press like growth promotants can have and has a lot of upside throughout the production chain. — Dr. Bob Hough