I mentioned in my last post that teeth can reveal the age of a sheep, but I did not go into any detail in order to avoid sounding like I was encouraging people to go sticking their hands and fingers into random sheep-mouths at the fair. Now that we have a safe time gap between the context of the last post and this one, here is the basic story behind telling a sheep’s age from its teeth with several different diagrams.
New lambs have “milk teeth,” which are small and uniform, these milk teeth will replaced by large permanent teeth. Sheep replace their milk teeth at a rate of a pair a year over a four-year period. It is recommend that ewes are purchased when they have one or two pairs of permanent teeth, when they are one or two years of age. This way they are old enough to have developed their immune systems, but young enough to have a long breeding life ahead of them.
After the sheep has all of its permanent teeth, the teeth will start to erode and separate from each other. This can be seen in the third diagram, in the set of drawn teeth labeled, “probably 8 years.” A sheep with missing teeth has a “broken” mouth. A sheep with no teeth is a “gummer.” It is better for a sheep to be a gummer than one with only one or two incisors, because a sheep is able to gum and use its molars enough to continue eating, while a sheep with a severely broken set of incisors will not have enough points of contact between teeth or gum to process grass and grain.
This is a very rough outline. The rate at which sheeps’ teeth erode is also dependent on diet, breed, local vegetation and terrain, and genetics.