I copied this article in part from a popular-press article and thought visitors might like to read this.

Even with an effective ID system in place, the U.S. may or may not find it easy to quickly and effectively determine animal age thresholds. On one hand, according to a report completed by Colorado State University (CSU) last summer, dentition accurately identified approximately 99% of the cattle younger than 30 months of age that were actually 30 months of age or younger. There were 0.16% classified as older than 30 months, which were actually younger.

There weren't enough cattle older than 30 months to get much of a feel for how many cattle 30 months and older might actually mouth as being younger than that.

The study included 7,671 head of fed cattle (48% heifers and 52% steers) harvested from January to the first part of June at eight different facilities in Colorado, Idaho and Texas. Researchers knew the actual age of the cattle, and then compared that with classifications made by dentition. The project was undertaken to demonstrate the accuracy with which dentition could be used in assessing actual age, in light of the industry's ban of Specific Risk Materials (SRMs) from cattle 30 months of age and older.

Depending on where age lines would be drawn for the purposes of resumed trade, though, the fact that estimating the age of cattle younger than 30 months of age using their teeth gets a lot sketchier.