Apr. 9, 2004 OVERTON – Steers with a bad attitude – those that are difficult to handle in pens and race out of handling chutes – will likely be tough eating, according to a cooperative study between Texas A&M University System and Mississippi State University researchers.
"The correlation between high-exit speeds and toughness was substantial," said Dr. Ron Randel, researcher with the Texas Agricultural Experiment Station at Overton.
"There was also a strong correlation between pen scores and toughness, but the pen scores are more subjective than the exit speeds," said Dr. Rhonda Vann, researcher with the Mississippi Agricultural and Forestry Experiment Station at Brown Loam.
Earlier work done by Randel and other Texas A&M researchers showed cattle that speed out of the handling chute ate less and gained less, but the Texas and Mississippi study is the first sin the United States that shows a strong correlation between temperament and meat tenderness. Work by an Australian researcher, Dr. Susan Burrows, has shown the same relationship is an inherited trait in similar breeds of cattle, Randel noted.
In the earlier U.S. studies, researchers used motion-detection devices to clock an individual animal's speed coming out of the handling chute – what's called the "exit speed." This measurement allowed them to take objective measurements that corresponded to the animal's excitability and tolerance to handling.
In the current study, exit speeds as well as two other measurements, "Pen Scores" and "Chute Scores," were taken.
CS is a measurement based on observation of behavior in the handling chute, ranging from 1 (calm, no movement) to 5 (jumping and rearing). PS ranges, which are taken when the animal is in a pen with other cattle, range from 1 (non-aggressive, not excited by humans) to 5 (aggressive; runs into fences or charges humans if approached.)
The study measured PS, CS and exit speeds of 58 crossbred steers twice – first, 21 days after weaning then 90 days after weaning.
Though long-used, the PS and CS scores rely on subjective evaluations by the observers, where the exit-speed measurements are as hard to criticize as a traffic cop's radar readings, Randel noted.
After the cattle were fed out, researchers recorded standard carcass data plus Warner-Bratzler Shear force data. WBS is the standard scientific measurement of meat tenderness. One or one-half inch cores are cut from steaks and inserted into the WBS machine, where they are sheared by a mechanically driven blunt knife. The force required to cut through the core is measured in pounds or kilograms.
At 21 days after weaning, exit speeds ranged from 0.21 meters per second (about 0.7 feet per second) to 3.67 meters per second (about 12 feet per second).
At 90 days after weaning, the recorded exit speeds ranged from 0.12 meters per second (about 0.4 feet per second) to 4.13 meters per second (about 13.5 feet per second).
The researchers found a correlation in both the 21-day and 90-day post-weaning exit speeds with toughness as determined by the WBS measurement. WBS scores ranged from 1.6 kilograms (about 3.5 pounds) to 4.4 kilograms (about 9.7 pounds). On the WBS scale, anything meat testing 10 pounds and above is considered "very tough."
"Shoe-leather tough," Vann said.
Beef that scores below 7 pounds is considered tender, with scores between 8 and 10 pounds considered "moderately tough."
Meat from five steers tested about 8 pounds, or moderately tough, with one animal having a score of nearly 10 pounds. All the animals with high WBS scores – "moderately tough" and tougher – had high exit speeds (average of 2.7 meters per second or 9 feet per second), Vann said.
"The story here is that if you have a set of calves with bad temperaments, they may wean at good weights," Randel said. "But whoever buys these calves will pay the price. Those calves are going to be more expensive to own and grade lower."
Randel and Vann agree that being able to tie measurable traits such as exit speed to carcass characteristics will ultimately result in a more consistent product for U.S. consumers. "It's a matter of consistency. That's one factor that hurts our industry as much as anything – inconsistency of product," Vann said.
Vann earned bachelor's and master's degrees from Texas A&M. She did her master's degree thesis and research while working with Randel in the early 1990s.
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