Anatomy - Gracey's Meat Hygiene - page 38

Table 2.8 Ages at which the permanent incisors appear

Pig
The period of eruption of temporary and permanent
teeth in pigs is subject to considerable variation, and
dentition is not a really satisfactory or accurate guide to
the animal's age. Estimation of the age in pigs is only
likely to be necessary in the case of show animals in con-
nection with their eligibility for particular age classes.
There is variation in the figures quoted by various
authorities as to the ages at which the permanent inci-
sors appear in the various animals. Sisson and Grossman
(1975) give the figures shown in Table 2.8.

First pair Second pair Third pair Fourth pair

Ox 1½-2 years 2-2 years 3 years 3½-4 years

Sheep 1½-1½ years 1½-2 years 2½-3 years 3½-4 years

Pig 1 year 16-20

months

8-10 months Canines

9-10
months

Horse 2½ years 3½ years 4½ years Canines

4-5 years

The corner pair of permanent incisors is subject to the
greatest variation in the time of eruption, and well-bred
cattle or animals that are well fed and well housed tend to
erupt their teeth earlier than scrub animals or those that
are poorly fed and poorly housed. In pedigree cattle, the
corner incisors may appear soon after completion of the
3rd year, and in bulls, they are not uncommonly present
at 2 years and 10 months.
The dental formulae for the temporary and perma-
nent teeth are shown in Table 2.5. The upper and lower
figures correspond to the teeth of the upper and lower
jaw. After the permanent incisor teeth have erupted, the
degree of wear on their cutting surface and the amount
of neck visible above the gums are a guide to the animal's
age. The neck of the central pair of incisors is perceptible
at the 6th year and that of the lateral centrals at 7 years,
of the laterals at 8 years, and of the corner incisors at 9
years. Subsequent to this, the incisor teeth are small and
much worn, and it is then possible to confuse an animal
1½ years of age, and therefore possessing all its milk inci-
sors, with an animal of about 10 years, but this can be
avoided by recognition of the exposure of the roots of the
teeth in the older animal due to shrinkage of the gums
and projection of the roots from the alveolar sockets.

Determination of sex

Cattle
Differentiation may be established between the carcase
of the bull, stag, bullock, heifer and cow.

Bull
The outstanding characteristic in the bull carcase is the
massive development of the muscles of the neck and the
shoulder, with the forequarter, except in well-bred ani-
mals, being better fleshed than the hindquarter. This
development of the crest is diagnostic in bulls, and in
some American packing houses, the funicular portion
of the ligamentum nuchae is cut at its insertion to the
dorsal vertebrae, the effect being to make the carcase
approximate more in appearance to that of the bullock.
In the dressing of the bull carcase, the testicles and
spermatic cord are removed, leaving an open external
inguinal ring partly covered by scanty scrotal fat. The pel-
vic cavity is narrow and can be spanned with the hand,
while the pelvic floor (ischiopubic symphysis) is angular
and the pelvic tubercle strongly developed. The bulbocav-
ernosus muscle, often referred to as the erector and
retractor penis muscle, is well developed, and the cut
adductor, or gracilis muscle, is triangular in shape; in
young bulls, however, the posterior portion of this muscle
is not covered with fat, and the gracilis muscle therefore
appears bean-shaped. The muscle of young bulls is light
or brick red in colour and similar to that of the bullock,
but in older bulls, it is dark red, dry and poor in fat.
In some European countries and the northern coun-
tries of South America, cattle are rarely castrated, and it
is the custom in dressing the carcase to leave the testicles
attached to the hindquarters. These organs are much in
demand by the population, many of whom regard them
as an aphrodisiac.

Sheep
The milk incisors in sheep are all present at birth or
shortly after and remain until the animal is 1 year old.
Where sheep are fed on turnips, however, a number of
the temporary incisors may be broken off before the ani-
mal is 1 year old.
A notch develops between the central pair of incisors
at 6 years of age. The formula for the temporary and per-
manent dentition in sheep is identical with that in
cattle.

Goat
It is generally accepted that up to 4 years of age, the goat
is as many years old as it has pairs of permanent incisor
teeth. Thus, a goat in which the last pair of permanent
incisors has erupted may be estimated as 4 years old.

Stag
If the male bovine is castrated later in life, at perhaps a
year old, it will have developed certain bullish character-
istics, the chief of which is the strong development of