Agriculture Reference
In-Depth Information
permanent teeth, starting with the inner two, that are noticeably larger. By
the time the sheep is about 4 years old, all of its lamb teeth have been replaced
by permanent teeth. After this point, it is no longer possible to accurately
determine an animal's age by its teeth, although you can make estimates
based on the condition of the teeth. It will also begin losing permanent teeth
at this point — hence the term “broken mouth.”
All that grinding action begins to wear down the sheep's teeth, shorten-
ing its useful life and thereby its lifetime. As the incisors wear down, the
amount of tooth below the gum line (about ∂ inch [1.3 cm]) is gradually
pushed out to help compensate for the wear. This is partly why the teeth
of an older ewe look so much narrower — the wider part at the top of the
tooth is being worn back toward the narrower center part of the tooth while
the even narrower part below the gum line is
being pushed up. With narrowing, gaps that
reduce the effi ciency of the ewe's bite occur
between the teeth. If you listen to an old ewe
grazing, you can hear sound as the grass slips
between her teeth.
On very short or overstocked pasture, the
wear is faster, because sand and soil particles
that are picked up as the animal grazes act
like sandpaper on the teeth. The closer to the
soil sheep graze, the more dirt and sand they
ingest. On short pasture, ewes must take more
bites to get a pound of grass, and each bite
contributes to the wear of their teeth.
2-year
3-year
4-year
5-year
6-year
7-year
Approximate annual
wear of sheep's teeth
lamb
yearling
2-year-old
3-year-old
4-year-old
older than 4 years
To some extent, you can determine the age of sheep by their teeth. In the front bottom
jaw, they have four pairs of incisor teeth — all small baby teeth that, like human baby
teeth, fall out to make way for permanent teeth. At about 1 year, the center pair falls out
and the fi rst pair of larger, permanent incisors appears. For each year until the sheep is
4 years old, it loses one pair of baby teeth and gains one pair of permanent teeth. After
a sheep turns 4 years old, you can't really tell its age by looking at the teeth.
