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Programs of national scale are available for breeders of Angus cattle to genetically improve carcass traits that relate to end-product value. These programs include collection of carcass and live-animal information that can be used to predict genetic differences between animals for both quality and yield traits.
Some of the first carcass data used to evaluate Angus sires were collected in 1974 under a structured sire evaluation program, and breeders have continued to participate in this program over the years to evaluate new and promising young sires. There are now more than 52,000 steer, heifer and bull carcass records in this database. This is the largest carcass database in the world that is sire-identified and can be used to genetically evaluate beef sires for carcass merit.
As one tracks the emphasis and interest in carcass testing over the years, from 1974 to the present, it becomes obvious that not a lot of emphasis was placed on carcass traits until the past decade. In 1986, only 225 carcasses were measured in the Angus structured sire-testing program.
In fact, I recall serious discussion being entertained on whether to continue this expensive program in which there seemed to be little interest. However, in the late 1980s, focus shifted from growth and maternal traits to the need to evaluate more Angus bulls for carcass traits, especially the need to find more sires that could help to increase the supply of cattle qualifying for the Certified Angus Beef® (CAB®) brand.
One of the positive aspects about carcass testing is that all of the carcass traits are moderately heritable, which allows for effective selection programs to take place. Generally speaking, the carcass traits associated with quality and yield are more heritable than the growth traits.
The only downside is the expense and time involved in getting sires through the testing and evaluation process. Most bulls probably do not enter a serious carcass progeny-testing program until they are 2 or 3 years old. Then, from the time a bull is entered into a testing program, it will be two or three more years before the expected progeny differences (EPDs) become available.
The length of time involved in carcass testing sires becomes a daunting exercise in the face of trying to compete against alternative animal protein sources that enjoy significantly shorter generation turnovers. With a national beef cow herd of more than 33 million cows and the fact that the majority of beef cows are still bred by natural service, is the idea of genetically retooling the national cow herd to produce a better end product an exercise in futility?

A new alternative
New methods and tools have to be exploited when the status quo will not get the job done. In the fall of 1998, a decision was made by the American Angus Association Board of Directors to take a bold step forward and to make a significant financial investment in an alternative method of evaluating Angus cattle for carcass traits. Was it the correct decision? I leave the answer up to you and time to determine.
The alternative method chosen by the Association was live-animal scanning using ultrasound. The concept was to scan yearling bulls for compositional traits and to forego the need for additional progeny testing.
Such a concept was hard to swallow for a lot of people. Ultrasound was not a new technology in 1998. In fact, the technology had been around for several decades. However, it is only within the past six to eight years that improvements in the technology and procedures for interpretation of ultrasonic images have provided accurate information.
Scanning of cattle in the 1980s and halfway through the 1990s produced erratic and almost unbelievable results in terms of ribeye sizes and the amount of marbling in yearling bulls. Skepticism about the results and a series of bad scanning experiences by many breeders were going to be hard to overcome.
The concept of centralized processing was the answer to many of these problems. This was the method to bring field technicians back to reality in their interpretations and to standardize procedures for collection and interpretation on a national scale.
Other issues of concern dealt with the relationship between ultrasound measures in yearling bulls and future carcass traits in steer progeny.

By the numbers
The research done at Iowa State University with both steer carcass traits and ultrasound traits is summarized in the tables. Table 1 lists the heritability estimates for the carcass traits, primarily based upon steer carcass data.
Table 2 lists the counterpart traits for the ultrasound traits being measured in yearling Angus bulls and in Angus replacement heifers. In general, the ultrasound trait heritabilities (shown in the boldface numbers) are significantly larger than the carcass trait counterparts. These results would indicate that ultrasound measures, under the current procedures of collection and centralized processing, provide more-accurate measures of body-composition traits than do cooler measurements on carcasses.

It is also known that contemporary grouping of yearling bulls being scanned is much tighter in terms of age ranges than in the carcass traits. This also could contribute to higher heritability estimates for the ultrasound traits. Regardless, selection programs using ultrasound EPDs should yield faster progress than programs using carcass EPDs.
Of equal significance is the genetic relationship between the yearling bull ultrasound traits and the counterpart traits in half-sibling steers and in future steer progeny (Table 3). The genetic relationship among the three major carcass traits [marbling, ribeye area (REA) and 12th-13th rib fat thickness] with their ultrasound counterparts is very high at more than 0.70. This means that the ultrasound EPDs for yearling bulls is an accurate indicator of what will be seen in future steer progeny.

The big step
It is interesting to contrast what is taking place in the Angus seedstock industry relative to carcass progeny-testing programs and the ultrasound program. The last few years of the carcass-testing program are graphically depicted in Fig. 1. Over the more than 25 years of the structured sire-testing program, 3,074 sires have been evaluated for carcass merit.
Fig. 2 positions the number of sires evaluated under carcass testing and under ultrasound testing on the same chart. Several points are apparent in Fig. 2. First, the number of sires evaluated with progeny ultrasound data in just three years’ time is almost double that of carcass testing that spans 25 years (7,196 sires through ultrasound vs. 3,074 sires). Second, the ultrasound information represents a new generation of information on Angus cattle relative to end-product merit. The average age of all sires with ultrasound EPDs is 6 years. The average age of the active sires with carcass EPDs is 13 years.Ultrasound scanning is shortening the generation interval of carcass testing.
Ultrasound in genetic evaluation programs offers the total beef industry a tremendous opportunity. The industry can use this technology to either (a) reduce subcutaneous fat by 0.1 inch (in.) while maintaining the same level of marbling or (b) increase marbling by one degree while maintaining the same level of external fat. The genetic correlation between these two traits is not all that great. Breeders can make directional changes in either trait without significant compromise in the other. Iowa State University researchers have determined that, if the beef industry would achieve either (a) or (b), it would add value to the tune of $1.35 billion/year for producers.
I believe that Angus breeders are doing their part in genetically defining a significant part of their gene pool as evidenced by the numbers of yearling bulls and heifers being scanned annually. Without question, the use of ultrasound EPDs by the commercial bull-buying industry quickly will move the industry in a direction to capitalize on this $1.35 billion value-added program.
Angus breeders, you are at the forefront of the seedstock industry relative to carcass merit, and congratulations on taking the big ultrasound step back in 1998.

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