Determining Age of a Sheep

Sheep farmers use the front teeth of a sheep to determine an approximate age of the sheep. How does a sheep farmer determine the age of the sheep?

First let us understand the eruption of teeth on sheep. Sheep have eight teeth on the lower front portion of the jaw named incisors. When a lamb is first born, the lamb has no teeth. As the lambs gets days old the lamb or baby teeth start erupting. When a lamb is three weeks old the lamb has all of their baby teeth. The lamb will keep these baby teeth or lamb teeth until it approaches one year of age.

Aging a sheep is approximate as sheep develop and mature at individual rates.

The first permanent incisors to appear are in the center of the lower jaw. The first incisors start to erupt when the sheep is close to 12 months and as late as 18 months or 1.5 years.

The blue lines point to the first incisors.

The second incisors appear when the sheep is approximately 1.5 years to 2 years of age.

The pink lines point to the second incisors.

The third set of incisors erupt through when the sheep is approximately 2.5 years to 3 years of age.

The purple lines point to the third set of incisors.

The final incisors are called corner incisors or canine incisors. The corner incisors erupt at approximately 3.5 years to 4 years of age. The eruption of the corner or canine incisors is the completion of the sheep getting their permanent teeth.

The purple lines point to the corner incisors or canine incisors.

Since lambs and 4 year old sheep have all eight incisors of the same size, how does a person know if the sheep is mature or a lamb. I chose pictures to help illustrate the difference in lamb teeth and sheep teeth.

Below are pictures of sheep I have raised so I know how old the sheep are. The photo of a five year old ewe’s teeth is on the left (white) and a five month old ewe lamb is on the right (black). Both sheep have all eight incisors. The teeth of both sheep meet the top gum allowing for most efficient biting of the forage for feed. The tops or tips of the teeth are shaped different. The older ewe’s incisors are flat on top. The lamb’s incisors are tapered with the longest part of the tooth on the outside and shortest part of the tooth next to the tongue. (Use the finger in the photos as a measuring tool to compare the size of the teeth).

Lamb teeth
5 year old ewe teeth

Below are some pictures of two ewes that are twins and age is 23 months. One has the second set of incisors totally erupted and the other is has one second incisors still erupting. The photos illustrate what a 2 year old sheep mouth looks like and how sheep mature at different rates.

23 month old ewe will all 2 year incisors.
Ewe with erupting 2 year teeth.

Below is a 3 year old ewe. The sheep has the first, second and third sets of incisors. The corner or canine incisor is still a lamb tooth and smaller than the permanent teeth.

Both of these ewes have their permanent incisors. Compare the shape of the teeth and the receding gum line of both ewes. Both of these sheep have good teeth and are able to forage for feed.

7 to 8 year old ewe
5 year old ewe

Below are examples of aged sheep or “smooth mouth” sheep. These sheep are approximately 8 to 9 years of age.

Aged ewe with chipped teeth
Ewe approximately 8 – 9 years, with retained lamb teeth in front

The photo above illustrates that sheep do not always do what they are expected to do. This ewe has retained the first lamb incisors in the center. Notice how her teeth are worn short. This sheep is a “smooth mouth” aged sheep.

Sheep also have molars that are shed and erupt in the same way the incisors shed and erupt. It is harder to see and photograph the molars. Sheep farmers need to check the molars as well to make sure the sheep is able to chew the food and the cud for proper digestion and obtaining nutrients. Some sheep farmer assume when there are gaps in the front incisors, the sheep has molars missing as well.

Sheep farmers need to check the teeth of their flock at least once a year, if not more. Teeth are needed for eating. Once a sheep reaches the age of loosing their teeth leaving gaps they should be culled from the flock. I have had sheep with gaps and I even purchased a ewe with no teeth and had to give her lots of tender loving care to get weight on her.


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