Know Her Age when Making Culling Decisions
Aging cows 101
G. Parker Jr., D.V.M.
In the competitive world of today's beef industry, producers cannot afford to keep marginally productive cows. One open or non-pregnant cow will rob the profit generated by two other good producing cows. In the face of high feed, fuel, and fertilizer prices, many producers are looking at decreased stocking rates or herd reductions. One of the criteria to selecting which cows to cull, is the age of the cow.
Older cows with short, worn, or missing teeth are not as efficient at harvesting forage (grass) and tend to not be in as good of body condition as younger "full mouthed" cows by the time winter weather arrives. After a season or two of being in thinner body condition the thinner cow will fail to breed back in time to calve in the normal calving season. This is why we age and pregnancy test in the fall; and, cull the older cows with short teeth that have failed to breed back with the rest of the herd during the summer and fall.
Cows are herbivors (grass eaters) that have a hard palate on the top part of the mouth and teeth only on the bottom jaw. These bottom adult incisors come in (erupt) consistently at a known age in the life of every cow. Determining the age of cows up to 5 yrs old is simple and accurate. Simply put, she has two permanent incisors as a 2 year old, four as a 3 year old, 6 as a 4 year old, and a full mouth of 8 permanent incisors when she is five. After five years, determining age is not as accurate, but close enough for practical purposes; since, we don't really care how many years old she actually is as much as we care how much longer she can efficiently graze.
Aging older cows is many times an educated guess. As she gets older, the teeth wear down to be less blade-shaped and more triangular and spaces start to appear between the teeth. As tooth wear continues the triangular shaped tooth wears down to a round (popcorn kernel) root. After the root wears off completely we call the cow "smooth mouthed" which means she has no teeth at all. There are several factors that can cause variation from the normal wear of teeth. These factors include: type of forage grazed, height of forage grazed, type of hay fed, sand content of the soil, and breed of cattle. The chart below should be helpful in learning to age your cows.