Source: Government of Manitoba
We’ve all heard the saying “Don’t look a gift horse in the mouth!” The latest information from Japan is suggesting that the Japanese Agricultural Ministry is considering a change to their blanket testing policy on animals. They are considering eliminating testing on animals younger than 20 months of age. We hear the United States trying to push this line to 24 months of age.
Differentiating age of cattle is easily done at six-month intervals all the way to 30 months of age. Dentition is the means of doing so and is the commonly accepted standard since BSE has become a substantial livestock-related problem. We receive many questions on this issue and the purpose of this summary is to provide producers and industry with a better understanding. The following article has been adapted from information published by the USDA.
There are three types of teeth found in the bovine: incisors, premolars and molars. Incisor teeth are found in the rostral (front) portion of the mouth, but they are absent from the upper jaw. The premolars and molars (known as cheek teeth) are found in the caudal part of the mouth and are present in the upper (maxilla) and lower (mandible) jaws. At birth, calves have deciduous (temporary, milk, baby) teeth. The deciduous teeth are lost as the animal ages and they are replaced by the permanent teeth.
Eruption Times of Permanent Teeth
|Teeth||Age at Eruption|
|First Incisor (I1*)||18–24 months|
|Second Incisor (I2)||24–30 months|
|Third Incisor (I3)||36 months|
|Fourth Incisor (I4 or C)||42–48 months|
|First Cheek Tooth (P2*)||24–30 months|
|Second Cheek Tooth (P3)||18–30 months|
|Third Cheek Tooth (P4)||30–36 months|
|Fifth Cheek Tooth (M2*)||12–18 months|
|Sixth Cheek Tooth (M3)||24–30 months|
|* I = Incisor P = Premolar M = Molar|
Figure 1 Click on image to enlarge
The deciduous incisors (Di) are much smaller than the permanent incisors. The crown (that part of the tooth that is covered with enamel) of the deciduous incisors are more narrow than the permanent incisors and they diverge more from the base (at the gum line) of the tooth to the apex when compared to the permanent incisors. Figure 1 compares the mandibles (lower jaws) from a young animal with deciduous incisors (black arrow) to an older animal with permanent incisors (white arrow). The difference in tooth size and shape and jaw width (and size) can be appreciated.
Cattle dentition is generally used as an indicator of age when actual birthdates are not available. Eruption times and wear of the teeth are the major factors used to estimate bovine age. The definition of eruption is the emergence, penetration or piercing of the tooth or teeth through the gingiva (the gum line).
An animal at 14 months of age would have a full set of deciduous incisors. All four pairs of teeth are temporary and firmly in place. The teeth are short, broad and usually have a bright, ivory color. There is usually space between the Di1 incisors. Other incisors may touch on the inside corner at the top of the tooth (Figure 2).
As the animal ages, the deciduous teeth become loosely set in the jaw, especially the central two incisors. The teeth appear longer and narrower (Figure 3) than in younger animals and the teeth may or may not be touching at the upper corners. An animal with this dentition is approximately 15 to 18 months of age old.
In Figure 4, a permanent central (I1) incisor has erupted. Temporary incisors may or may not be present when the permanent incisor erupts.
The permanent incisors usually erupt at an angle (Figure 5) and straighten into a definite pattern with growth. In Figure 5 both central (I1) incisors have erupted. They may or may not be in straight line with the incisor corners touching.
The central incisors are in place in Figure 6. They have straightened and the inside corners are in line. Animals with eruption of one or more central incisors are considered to be 18 to 24 months of age.
When one or both middle (I2) incisors erupted the animal is considered to be 24 to 30 months of age (Figure 7).
For more detailed information, see the USDA Food Safety and Inspection Service (FSIS) webpage on Using Dentition to Age Cattle.
Farm Production Extension Specialist – Beef
Livestock Knowledge Centre
Manitoba Agriculture, Food and Rural Initiatives