The recent Beef Improvement Fede r a t i o n (BIF) Conf e r e n c e held in Bozeman, MT, was a highlight for anyone interested in beef cattle genetics, efficiency and new technology. For background, beef production is the fourth largest U.S. manufacturing industry with $71 billion retail equivalent value in 2006 (www.ers.usda.gov), and a genetic improvement of 1 percent would add $0.7 billion annually to the U.S. economy. BIF showed that there are many ways this could be done, including selecting genomically for cattle resistant to bovine respiratory disease, etc., but I would like to discuss one interesting presentation by Dr. Dorian Garrick of Iowa State University who bore in on efficiency.
Garrick introduced the idea of efficiency from two views: 1) Dilution of Maintenance, and 2) Net Efficiency.
This article will look primarily at Dilution of Maintenance and what we have accomplished as an industry up until this time.
Dilution of maintenance can be achieved by reducing cow/calf feed requirements. This would include cow size, replacement rate and reproductive success. You dilute this maintenance when these are combined with increased growth rate and heavier finished weights.
What is our report card?
We certainly have increased growth and harvest weights, with 1,000-pound carcasses now not discounted. We adopted growth expected progeny differences (EPDS) readily, starting in the mid-1980s, increasing yearling genetic merit 120 pounds from 1985 to 2007.
Garrick feels this has resulted in dilution of maintenance, but I am not so sure.
With increased growth has come increased cow size. This has been well documented, but only two breeds have any sort of mature cow maintenance genetic selection measures: Red Angus’ mature cow maintenance energy EPD, and Angus’ cow energy value. Where are the other breeds in controlling cow maintenance inputs? The only saving grace for the industry is there seems to be some correlation between birth weight and mature cow size, and in breeds that have started to get birth weight in check, mature cow weights seem to be leveling for those breeds. Many of the Continental breeds have benefitted from that.
In terms of dilution of maintenance by reducing replacement rate and improving reproductive success, reproduction has been another area the breeds have lagged behind. Limousin was the first to come out with a scrotal circumference (SC) EPD in 1994 and many other breeds followed suit. This was in a two-fold effort, one to increase yearling bull fertility, and two to increase rate of conception of yearling heifers. Science from as early as the late 1960s had shown that daughters out of larger SC bulls reached pu berty earlier than smaller SC bulls in their contemporary group.
This all sounds good, but around the year 2000 when the industry was on a “scrotal” fad, it started to have trouble with extremely large SC bulls having temperature regulation problems and being prone to injury. Colorado State University also came out with a study that demonstrated that SC in yearling bulls was confounded between puberty and growth, i.e. they could have larger SC in a contemporary group because they reached puberty earlier or because they were just bigger in body size. The answer is a heifer pregnancy EPD. Red Angus released it in a 2002 Reproductive Sire Summary, and Angus has released an experimental EPD. Again, the industry has not moved very far forward on this front, and in terms of the puberty argument and SC, the recent data released by U.S. Meat Animal Research Center had the breeds with latest puberty and earliest puberty being the two worst breeds for heifer pregnancy. Breeds need to go with the economically relevant trait of a heifer pregnancy EPD while SC should be a threshold trait when selecting bulls.
Stayability is the probability of an animal staying in the herd past six years of age. Red Angus led with this EPD in 1995. Simmental implemented it, but initially had some noise in the model during their breeders’ rapid switch from red to black cattle. A couple other breeds now have also adopted the trait, but the three largest breeds have not.
There has not been much implemented by the breed associations on Net Feed Efficiency with the exception of the leadership of the American Angus Association. In the fall of 2010, they came out with residual average daily gain, which is expressed in pounds per day and is a predictor of a sire’s genetic ability for postweaning gain in future progeny compared to that of other sires, given a constant amount of feed. Best of all, they have the genomics to back it up given that collecting the phenotypes are so difficult. No one else is close to Angus at this point on this front.
To say the least, we have a long way to go as an industry. Hopefully, we will get new research, but we still have a lot to do with implementing what we already have available to us. We also cannot, as an industry, become overly fixated with decreasing maintenance costs without a reasonable balance of postweaning gains and harvest weights. We should try to do both, and with the proper genetic predictions, outliers can be found. We are a multi-tiered industry, and each segment wants a reasonable expectation of profitability. — Dr.
Bob Hough [Dr. Bob Hough has served as the executive vice president of the Red Angus Association of America 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.]