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For
many years, producers, veterinarians, and exhibitors (at cattle shows) have
used cattle dentition to make general age determinations. Dentition
will vary from herd-to-herd and animal-to-animal, because of the animal’s
genetics, their diet, and the varied geographical locations in which they are
raised. Despite individual differences, when the age of an
animal is not known, examination of the teeth serves as the best and most
practical method of age determination. This document will
serve as FSIS guidance for aging cattle.
In
order to age cattle using dentition, some background information is
necessary. This document will discuss and demonstrate: types of
teeth and their location in bovine jaws, deciduous incisors versus permanent
incisors, eruption times for deciduous and permanent teeth and using eruption
times of permanent incisors to age cattle.
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Tooth
types and location
There
are three types of teeth found in the bovine: incisors, premolars and
molars. Incisor teeth are found in the rostral 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. The
following schematic (Figure 1) of the bovine
skull, from an older animal (all permanent teeth* are present),
demonstrates the location of the teeth.
Figure 1
*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.
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Deciduous
(Temporary) Teeth
Calves have a total of 20 deciduous teeth. There are no deciduous molars and
deciduous premolar 1 is not present. The dental formula for the
deciduous teeth follows:
Deciduous
teeth: 2(Di
0/4, Dc 0/0, Dp 3/3) = 20 deciduous teeth
The
eruption of the deciduous teeth varies somewhat; about 75 percent of the
well-bred calves have all incisors erupted at birth. Average
periods of eruption of the deciduous teeth in cattle follow:
Table 1 – Eruption Times of
Deciduous Teeth
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Teeth
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Age at eruption
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First
Incisor (Di* 1)
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Birth
to 2 weeks of age.
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Second
Incisor (Di 2)
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“
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Third
Incisor (Di 3)
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“
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Fourth
Incisor (Di 4 or C)
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“
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First
Cheek Tooth (Dp* 2)
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Birth
to a few days of age
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Second
Cheek Tooth (Dp 3)
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“
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Third
Cheek Tooth (Dp 4)
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“
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* Di = deciduous
incisor Dp = deciduous
premolar
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In photograph 1, the rostral view of a mandible from a young bovine
demonstrates the location of the different deciduous incisors; they are
identified – Di 1 through Di 4.
Photograph 1
Click
on the photograph for an enlarged image.
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Permanent
Teeth
Deciduous
teeth are replaced by permanent teeth as the animal ages. Premolar
1 is not present. The dental formula for the permanent teeth of
cattle follows
Permanent
teeth: 2(I
0/4, C 0/0, P 3/3, M 3/3) = 32 permanent teeth
Average
periods of eruption of the permanent teeth in cattle are found in the
following table:
Table 2 –
Eruption Times of Permanent Teeth
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Teeth
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Age at eruption
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First
Incisor (I* 1)
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18
– 24 months
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Second
Incisor (I 2)
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24
– 30 months
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Third
Incisor (I 3)
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36
months
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Fourth
Incisor (I 4 or C)
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42
– 48 months
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First
Cheek Tooth (P* 2)
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24
– 30 months
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Second
Cheek Tooth (P 3)
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18
– 30 months
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Third
Cheek Tooth (P 4)
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30
– 36 months
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Fifth
Cheek Tooth (M 2)
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12
– 18 months
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Sixth
Cheek Tooth (M 3)
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24
– 30 months
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* I =
Incisor P =
Premolar M = Molar
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The
photograph (Photograph
2)
below shows a mandible from a cow with all of her permanent incisors
present. The incisors are identified – I 1 through I
4.
Photograph 2
Click on the
photograph for an enlarged image.
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Note:
In addition to the simple numerical designations for teeth, the following
terms are commonly applied to the individual incisors: central (Di 1 or I 1),
first intermediate or middle (Di 2 or I 2), second intermediate or lateral
(Di 3 or I 3), and corner incisors (Di 4 or I 4). Canine teeth are
absent in cattle, unless the fourth incisor (I 4), or corner incisor, is
considered to be a canine tooth. If Di 4 or I 4 is
considered to be a canine tooth, then the dental formulas change, slightly,
to the following:
Deciduous
formula: 2(Di 0/3, C 0/1, Dp
3/3) = 20 teeth
Permanent
formula: 2(I 0/3, C 0/1, P
3/3, M 3/3) = 32 teeth
A
dental formula is an abbreviated statement of the number and types of teeth
found on one side of the top and bottom jaw. Because the
dentition is the same on both sides of the jaw, the formula lists only one
side, and is enclosed in parentheses and multiplied by 2 to arrive at the
total number of teeth. Numbers above the
lines are for the teeth located in the upper jaw and those below the line are
for the teeth in the lower jaw.
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Deciduous
(temporary) incisors versus permanent incisors
The deciduous incisors differ from the permanent incisors in being much
smaller. The crowns (that part of the tooth that is covered with
enamel) of the deciduous incisors are narrower then 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. Photograph 3
compares the mandibles (lower jaws) from a young animal with deciduous
incisors (red 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.
Photograph 3
Click on the
photograph for an enlarged image.
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Using
teeth to age cattle
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. This
guidance document will base the aging of cattle on the eruption times for the
permanent incisors.
The definition
of eruption is the emergence/penetration/piercing of the tooth/teeth
through the gingiva (the gum line).
Eruption
of teeth in cattle typically follows the pattern shown in the Figures
2 - 7 below. The figures represent the incisor dentition
from young animals through animals that are 30 months of age or older.
An
animal 14 months of age would have a full set of deciduous incisors as shown
in Figure 2. 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 Di 1
incisors. Other incisors may touch on the inside corner at the top
of the tooth. As the animal ages, the deciduous teeth become
loosely set in the jaw, especially the central 2 incisors. The
teeth appear longer and narrower (Figure 3) then in younger
animals and the teeth may or may not be touching at the upper corners; an
animal with this dentition is approximately 15 – 18 months of age.
In Figure
4, a permanent central (I 1) 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 (I 1) incisors have erupted; they may or may not be in a straight
line with the inside corners touching. The central incisors, in Figure
6, are in place, they have straightened and the inside corners are in
line. Animals with eruption of one or more central incisors are
considered to be 18 – 24 months of age. When one or both middle (I
2) incisors erupt the animal is considered to be 24 – 30 months of age (Figure 7).
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The
following sets of photographs will demonstrate the aging of cattle, based on
dentition, from 15 months to greater then 42 months of age. These
animals were aged using Table 1 and Table 2 above. The photographs
will show a rostral view and at least one rostrolateral view
of each set of teeth. (The following
photographs are thumbnails, so please click on them to get the enlarged
image).
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Cattle 15 – 18
Months of Age
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The
following four photographs show a rostral (Photograph 4a and 5a) and rostrolateral
(Photograph
4b and 5b)view
of the dentition on the lower jaw. All deciduous incisors are
evident. These temporary teeth are often loosely set in the jaw;
especially the central incisors (Di 1). The animals are
approximately 15 - 18 months old. In photographs 5a and 5b, the central
incisors were very loose. Also, as described for Figure 2 above,
the incisors are longer and narrower when compared to younger animals.
Click on the
photograph for an enlarged image.
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Cattle 18 – 24 Months of Age
The
eruption of the first central incisor (or incisors) indicates that the animal
is in the age range of 18 – 24 months as indicated in Table 2 above. The
Di 1 deciduous incisors may or may not be present when the central incisors
erupt.
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The
following three photographs show the eruption of the central (I 1) permanent
incisors; the deciduous incisors have been lost. One incisor
(white arrow), in photograph 6a, has recently erupted while the other incisor
(red arrow) has been exposed, due to the gingiva being artificially torn
during processing; this incisor had not penetrated the gum line. Photograph
6c gives a better view of the erupted incisor (white arrow).
Click
on the photograph for an enlarged image.
These
photographs (7a
and 7b)
show that the central incisors (I 1) have erupted and are fully developed,
but are not in wear. The eruption of the central incisors
indicates that the animal is in the 18 - 24 month age range. White
arrows identify the central incisors in photograph 7a.
Click on the
photograph for an enlarged image.
Photographs
8a and 8b show that the central incisors have erupted. These
incisors are fully developed. This animal is in the 18 - 24 month
age range.
Click on the
photograph for an enlarged image.
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Cattle 24 – 30 Months of Age
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Cattle
that have the middle (I 2) incisor (or incisors) erupted are in the 24 – 30
month age range as indicated by Table 2 above.
However, FSIS, as written in FSIS Notice
5-04, is using a conservative approach and is determining that cattle
with eruption of at least one of the second set of permanent
incisors (I 2) is 30 months of age or older. FSIS would consider
the animal in photographs 9a – 9c to be 30 months of age or older;
the animal in photographs 10a and 10b is also considered to be 30
months of age or older.
These three photographs (9a – 9c) show the eruption of the middle (I 2)
incisors. The white arrows in photograph 9a locate the I 2
incisors; the central (I 1) incisors (found between
the I 2 incisors) have erupted and are fully developed. Photographs 9b
and 9c are rostro- lateral views of the lower jaw. These
photographs demonstrate the variation in eruption of the I 2 incisors. The
I 2 incisor (white arrow) in photograph 9c has recently erupted.
Click on the
photograph for an enlarged image.
In
photographs 10a and 10b, the central (I 1) and middle (I 2) set of incisors
have erupted.
The I 1 incisors are identified by the white arrows and I 2 incisors by
the red arrows in photographs 10a and 10b.
Click on the
photograph for an enlarged image.
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Cattle Greater Than
30 Months of Age
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The
eruption of the lateral (I 3 or second intermediate) incisor (or incisors)
indicates that the animal has reached 36 months of age. The
eruption of the corner (I 4) incisor (or incisors) indicates that the animal
has reached at least 42 months of age. These ages are based upon
permanent incisor eruption times found in Table 2 above.
The
following 4 sets of photographs are representative of animals that are at
least 42 months of age or older. These photographs (as you move from
Photograph 11 through 14) also demonstrate that as cattle age the teeth are
worn down. Photographs 14a and 14b demonstrate what happens after
years of use; the teeth have worn down to what are called “peg teeth”.
Click on the
photograph for an enlarged image.
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References
1. Sisson, S and
Grossman, J. D. The Anatomy of Domestic Animals. 4th edition,
1953. W. B. Saunders, Philadelphia .
2. Getty, R. Sisson
and Grossman’s: The Anatomy of the Domestic Animals. 5th edition,
1975. W. B. Saunders, Philadelphia .
4. Nickel, R,
Schummer, A, Seiferle, E and W O Sack. The Viscera of the Domestic
Animals. 1973, Springer-Verlag , New York .
6. The Stockman’s
Handbook. 6th Edition
by M. E. Ensminger, Copyright 1983 by Interstate Printers and Publishers.
For further clarification or
questions about this correlation material please contact the Policy
Development Division
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