1. To determine and document the effectiveness of using dentition to verify actual ages
of cattle in the U.S. fed beef population.
<P>2. To determine if USDA skeletal maturity could be used, instead of dentition, to verify
actual ages of cattle harvested in U.S. fed beef plants.
Findings: Sampling procedures resulted in reasonably balanced proportions of heifers and steers and adequate representation of the three predominant cattle types (British, Brahman, and Continental European) in the U.S. beef cattle population. A small group of Mexican-type (Corriente) steers was included in the sample, but no dairy cattle were sampled. Consistent with the focus of our sampling efforts, most (85%) of the cattle were 18 months or older. However, an obvious deficiency in the sample is the small number of cattle with actual ages of 30 months and older. Dentition also seemed effective for identifying cattle with actual ages of 30 months or older, correctly classifying over 94% of the cattle in this age category. Of concern, from the standpoint of SRM control, is the fact that 5.9% of the cattle with actual ages of 30 months or older were misclassified as being less than 30 months old.
<P>Skeletal maturity was not consistently related to differences in actual age and, therefore, was not effective for use in identifying cattle 30 months old or older. Of the cattle with actual ages of 30 months or older, 59.7% were incorrectly classified as being less than 30 months old based on their skeletal maturity scores. Though carcass skeletal maturity, as used in the Official U.S. Standards for Grades of Carcass Beef (USDA, 1996), has been shown to be effective for classifying beef carcasses into expected-palatability groups (Hilton et al., 1998), results of the present study suggest that skeletal maturity has little value for verifying ages of cattle whose actual ages are unknown.