The age of cattle can be approximated closely by the
appearance, development, and subsequent wear of their second
incisor teeth. Cattle have eight incisor teeth, all in the lower jaw.
In the calf at birth two or more of the temporary or first incisor teeth
are present. With the first month the entire eight incisors have appeared.
Fig. 1.—Internal face of incisors of the calf.
As the animal approaches 2 years of age the center pair of temporary
incisor teeth or pinchers are replaced by the permanent pinchers
which at 2 years attain full development.
Fig. 2.—Internal face of incisors at 2 years.
At from 2½ to 3 years the permanent first intermediates are cut
and are usually fully developed at 3 years.
Fig. 3.—Internal face of incisors at 3 years.
At 3½ years the second intermediates or laterals are cut. They are
on a level with the first intermediates and begin to wear at 4 years.
Fig. 4.—Internal face of incisors at 4 years.
At 4½ to 5 years the corner teeth are replaced, the animal at 5
years having the full complement of incisors with the corners fully
developed.
Fig. 5.—Internal face of incisors at 5 years.
At 5 to 6 years there is a leveling of the permanent pinchers, the
pinchers usually being leveled at six and both pairs of intermediates
partially leveled and the corner incisors showing wear.
From seven to eight the pinchers are noticeably worn; from eight
to nine the middle pairs, and by ten years the corner teeth.
After 6 years the arch gradually loses its rounded contour and
becomes nearly straight by the twelfth year. In the meantime the
teeth have gradually become triangular in shape, distinctly separated,
and show the progressive wearing to stubs.
Fig. 6.—Internal face of incisors at 12 years.
