Known as dentition, this additional carcass evaluation tool is also used to classify carcasses into age categories to meet export requirements. Dentition has also played a crucial role in modernizing carcass evaluation standards.
Official use of dentition to determine cattle ages followed the first bovine spongiform encephalopathy (BSE) incident in a Washington state dairy cow in December 2003. Although the risk of BSE developing in American herds is very low, the USDA immediately implemented dentition in U.S. slaughterhouses on January 12, 2004.
USDA graders used dentition to objectively sort animals into age groups and to prevent a potential food safety issue.
The voluntary beef carcass grading system under the Agricultural Marketing Service (AMS), an agency of the USDA, is a marketing system rather than a food safety regulatory system. In the past, it relied solely on bone ossification and lean characteristics to determine carcass maturity, with grades of A-maturity through E-maturity, A being the youngest.
A-maturity qualified for Prime, Choice, Select or Standard grades. B-maturity qualified for Prime, Choice or Standard. A C-, D- or E-maturity, if graded, would be identified as Commercial, Utility or Cutter/Canner.
Ossification
Ty Lawrence, Ph.D., director of the Beef Carcass Research Center at West Texas A&M University, says animals add cartilage cells (chondrocytes), which grow in a column on bone growth plates. Older cartilage cells convert to bone in a process called ossification, which is controlled by the estrogen hormone.
“Estrogen in females is driven by an estrus cycle every 21 days,” Lawrence explains. “There’ll be a spike and a trough of estrogen in that cycle. In addition, when the heifer becomes pregnant, the placenta produces copious amounts of estrogen as part of its normal growth process for the fetus. The excess amounts of estrogen close the bone growth plate by [signaling] the chondrocytes to stop growing and complete the ossification process.”
In male cattle, testicles produce both testosterone and estrogen, which is aromatized, causing bulls to stop growing. Lawrence reports a steer continues to grow until it reaches a balance between feed intake and body maintenance.
Keith Belk, Ph.D., Colorado State University, says there are locations in which cattle appear older than their chronological age. Yearlings fed on grasses in some parts of the Nebraska Panhandle and Sandhills are more physically mature than their counterparts at the same chronological age. Producers of these particular cattle tend to have more carcasses penalized in the grading process.
“We think it’s an estrogen problem, [because] some of the grasses are higher in phytoestrogens,” Belk explains. “The consequence is cattle fed on that grass tend to mature a little bit faster.”
Unfair grading
The U.S. slaughters some 26 million commercially fed cattle annually in addition to another six to eight million culled cows and bulls. If graded, culled older animals are typically assigned grades that are over a C-maturity, which includes Commercial, Utility or Cutter/Canner designations.
However, in practice, these grades are rarely used because consumers prefer products with better grades, such as Choice and Prime.
On the fed cattle side, 95 percent are evaluated and tend to grade as an A-maturity level because all fed cattle slaughtered in the U.S. are young. Teams of researchers from Colorado State University conducted a joint study with the USDA, which reported the average age at slaughter was 17 1/2 months of age (MOA).
Consequently, those animals received the highest grades of Prime, Choice, Select or Standard. There was some grade variability due to longer-fed Holsteins, as well as cattle harvested much younger.
“The few cattle that fell into the B-maturity category, based on their skeletal maturity and their lean maturity, which is how we evaluated maturity in the past, were sometimes misclassified,” Belk explains. “We knew they were younger.”
Belk says the grading procedure was never supposed to be based on chronological age, but physiological age. A Colorado State University study conducted by Daryl Tatum, Ph.D., suggested it did not matter whether physiological or chronological data was used. Researchers found no difference in the accuracy of quality grades utilized to sort carcasses, age-related differences and beef tenderness.
This research pointed to the unfair grading of some carcasses that, for whatever reason, ended up in the B-maturity category. For example, if a heifer became pregnant early, and then lost her calf, she often went to a feedlot before being harvested. Although the heifer was 30 MOA or younger, her carcass could have been scored as a C-maturity, with a significantly discounted price.
In contrast, a 5-year-old steer could have an A-maturity carcass. Incorrectly classified carcasses resulted in significant financial losses to the beef industry ranging in the millions of dollars annually.
In 2016, representatives of organizations, including the National Cattlemen’s Beef Association (NCBA), American Farm Bureau Federation (AFBF) and U.S. Meat Export Federation (USMEF) requested the AMS modernize the U.S. standards for carcass beef grades.
Beef industry producers should know the U.S. is the only country that has a true, federal third-party grading system that applies carcass grades independently from a packing plant.
Updates to the grading standards
Colin Woodall, vice president of government affairs for NCBA, reports many carcasses were only graded based on skeletal maturity indicators, including observation of the ossification of bones and cartilages along the vertebral column of the split carcass. Animals with premature skeletal ossification, which can happen naturally in approximately 7 percent of graded carcasses, were usually placed in the B- or C-maturity category.
“For some cattle, premature ossification means they are incorrectly deemed older than 30 months of age and therefore ineligible for USDA quality grades,” Woodall explains. “Under the new method, additional benefits will accrue to producers who will now be eligible to receive USDA quality grades for more of their cattle. Ultimately, this maximizes the value of each head.”
U.S. beef cattle producers are fortunate the AMS-USDA listened to experts who promoted the modernization of beef grading standards. In December 2017, the USDA updated the voluntary U.S. Standards for Grades of Carcass Beef. New changes provide companies using the USDA grading program with the option to use dentition or age documentation, such as detailed production records, to ensure animals are 30 months old or younger.
Woodall explains, “Updates to the beef grading standards will benefit U.S. beef producers in every segment of our industry. Beef industry representatives from the cow-calf, feeder and packer segments conservatively estimated incorrect classification of carcasses cost the industry nearly $60 million annually. Carcasses incorrectly classified were sold at an estimated discount of nearly $275 per head.” 
PHOTO: The updated standards should help alleviate errors in the grading system. Photo by Getty Images.
Gilda V. Bryant is a freelancer based in Amarillo, Texas. Email Gilda B. Bryant.
