Ultrasound has several applications in beef cattle managementWritten by Christy Hemken
University of Wyoming Extension Beef Cattle Specialist Steve Paisley is one of a handful of certified technicians in Wyoming who ultrasound beef cattle for carcass traits.
“The correlations between the ultrasound image and actual carcass data are between 76 and 93 percent accurate,” says Paisley. “The heritability of carcass traits is 38 percent, compared to reproductive traits at 10 to 15 percent, so there’s an ability to make rapid changes to a herd because the carcass traits are highly heritable.”
Paisley says a primary location to scan for carcass traits is backfat thickness, which is the most accurate ultrasound measurement because it’s strictly linear.
“Backfat thickness determines how much fat, or cover, is on the animal. It’s used almost exclusively in feedlots, but that’s also an indicator of energy reserves on a cow and her insulation for cold weather,” he explains.
When measuring ribeye area, Paisley says software is used to trace the ribeye area in the image and measure in square inches. “We look for specific landmarks in the ribeye to make sure we’re ultrasounding every animal at the same location,” he notes, saying it’s important to get repeatable, accurate information.
“The ribeye is harder to measure than backfat because it’s two-dimensional,” he says, noting the correlations are also a little lower at 76 percent. “The measurement hinges on a lot of things, like how the animal stands in the chute, the location of the probe and quality of the image. All those can impact how the ribeye is measured and traced.”
A third measurement commonly taken is marbling, or intramuscular fat, accomplished by rotating the probe 90 degrees from where the ribeye measurement is taken.
The software technicians use has algorithms built in that evaluate the image, taken between the 12th and 13th rib, and display overall brightness of the tissue.
“A dark image indicates very little marbling,” says Paisley, adding the software also takes texture and density into account. “Large light flecks are discounted, because they’re connective tissue and not fat. Marbling shows up as fine dots.”
Although USDA grades beef based on marbling, or intramuscular fat, Paisley says today only three percent of cattle grade prime. “It’s a small percentage of the market, because right now there’s not a lot of incentive for an emphasis on marbling by producers,” he says.
On the seedstock end of ultrasound, Paisley says he collects images – one ribeye, four intramuscular fat and one rump fat – that are sent to an interpretation lab, after which they’re used for EPD values and genetic markers.
At the Range Beef Cow Symposium XXII, Paisley says Pfizer Animal Health will be present to debut their system, which now features 50 markers that have moved from eight to 10 percent accuracy to nearly 50 percent accuracy.
“There’s 10 times more ultrasound data going into EPDs than actual carcass data, and we can test steers, bulls and evaluate females and heifers,” says Paisley.
He says with chuteside ultrasound applications a technician and producer can view and interpret images at the chute, making herd selections and management decisions on the spot. Paisley recommends ultrasound when choosing replacement heifers.
“If you know you’ve been producing calves with small ribeyes, or a high percentage of yield grade 4’s, you can make selection decisions on replacements and, because it’s a highly heritable trait, you can move the herd dramatically with the right bull choices and weed out the lower end of your heifers,” explains Paisley.
Paisley says there’s a good genetic correlation between bull ultrasound data and the steers they produce. “A bull that’s above breed average in ribeye area or marbling will correlate down to the steer calves he produces,” he says.
Weight and frame score combined with backfat, ribeye area and marbling can determine what heifer will work best in a producer’s environment. “The heifers can be ranked, and by removing inferior animals the whole group can move upward,” says Paisley.
He cautions that heifers need to be measured at a point in time just prior to breeding. “Evaluating replacements when they’re all on a good plane of nutrition under the same management is the best time to measure them,” he says.
In mature cows ultrasound can help determine body condition scores. “A cow with a low body condition score has a smaller ribeye, because she’s mobilizing muscle tissue as well as fat. If you start feeding her well she won’t bounce back immediately because she’s got to rebuild that muscle,” he explains.
Regarding chuteside application in fed cattle, Paisley says it’s a good way to determine the economics of feeding and a good endpoint for the steers. “You can avoid making them overly fat and putting additional feed in the animal,” he says.
Paisley mentions the Decatur Feedlot, which operates on the philosophy there’s a correlation between evaluating weaned calves and their yield and quality grade when they’re finished 140 days later. That thinking led to a beef sorting system with seven stations and four chutes. After all the calves are sorted and fed according to the ultrasound data, they should be fed the right number of days to get the most economical gain and achieve desired traits.
Paisley says ultrasound data can also help determine what implant to use and how to implant for the best results. In a UW study steers implanted with the assistance of ultrasound increased ribeye area by over one square inch, and lean muscle gain was increased.
Despite the demonstrated benefits and results of ultrasounding cattle and producing and feeding according to that data, Paisley says there remains a gap in marketing.
“We’re buying live with no regard to quality of the carcass,” he says, noting 80 percent of cattle are marketed live. “At one time we were trending toward more cattle marketed on grids, rewarding lean cattle high in marbling. Now there’s inefficiency in the industry, because there’s more demand than supply for high grade beef.”
“Ultrasound can be used as an initial sorting tool to create more uniform marketing or groups of cattle, and it can be used from research standpoint to estimate body reserves,” says Paisley in summary. “A producer can feed different supplements to range cows and see differences in weight change, whether they be muscle gain or additional fat. He can also use ultrasound in a mature cowherd to evaluate nutritional programs.”