The approximate age of cattle may be determined by examining the teeth as illustrated in Diagram 1. The tooth method of aging cattle involves noting the time of appearance and the degree of wear on the temporary and permanent teeth.
The temporary or milk teeth, are easily distinguished from the permanent teeth by their smaller size and whiter color. At maturity, cattle have 32 teeth, eight of which are incisors in the lower jaw. The two central incisors are known as pinchers; the third pair are called second intermediates or laterals; and the outer pair are known as the corners. There are no upper incisor teeth; only the thick, hard dental pad.
The tooth method of aging cattle is more accurate when animals are grazed for their entire life on “soft feed” (irrigated pasture). Under rough feed conditions, such as desert rangelands, teeth are worn at a much faster rate. Under rough feed conditions, accuracy of aging cattle is reduced, particularly in animals over five years of age where tooth wear is the only indicator.
Adjusting the accompanying chart to match feed conditions is essential to accurately determine the age of cattle. The best way to adjust the accompanying age chart to an individual ranch is to examine teeth of individuals with known ages and adjust the scale depending on wear.
Becoming proficient at aging cattle by the tooth method requires practical experience and a lot of practice. It also requires theoretical knowledge of the information presented in Diagram 1.
A second method of aging cattle involves reading the brucellosis tattoo in the right ear of female cattle. The tattoo (if legible) will reveal the year that the cow was a weaned calf and brucellosis vaccinated.
The first digit of the tattoo represents the quarter of the year that the animal was vaccinated. For example, a two would mean the animal was brucellosis-vaccinated in April, May or June. The middle portion of the tattoo is a shield.
The last number is the year the animal was vaccinated. For example, a 7 would mean the animal was vaccinated in 1997, as a calf. The calf could have been born in 1996 or during 1997. Brucellosis tags don’t reveal the year of birth, only vaccination.