Question: I bought a small herd of cows, all represented to be 3 to 5 years of age. I am not sure I wasn't sold some cows a lot older. How accurate is mouthing cows in determining their age?
Answer: Teeth can be very helpful in aging cattle. Based on a table from the USDA and Mississippi State University Extension, I can tell you the first incisors show full development around 36 months, leveling at 5 to 6 years, with noticeable wear at 7 to 8 years.
After 4 to 5 years of age, guess replaces estimate. But, we can at least make our guess an educated one. Aging a cow by her mouth is based on wear levels of the teeth. As you might think, this can vary greatly depending on what the cow eats and even breed.
Animals grazed on sandy land in Florida, those fed coarse or gritty grains, or those grazing coarse native forages in the Western Plains will show more wear to teeth than cattle on improved forages common in the eastern U.S. Crossbred cattle and Brahman-influenced cattle maintain incisors longer.
Compare the teeth of cattle with known ages to those animals you are trying to estimate age. Doing this can help you develop a system that works for your area.
While I learned the aging formula chart as a child, I also was taught the incisions "necked out," or showed a narrowing just above the gumline, beginning at about age 6 for the first incisor, age 7 for the second, age 8 for the third and age 9 for the fourth or outside incisor. It has worked for me, but if others have systems that work for them, please pass them on.
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