At cow culling time, producers often face some tough decisions. Optimum culling of the herd seems to require a sharp crystal ball that could see into the future. Will she keep enough body condition through the winter to rebreed next year? How old is the cow? Is her mouth sound so that she can harvest forage and be nutritionally strong enough to reproduce and raise a big calf? At what age do cows usually start to become less productive? Obviously there is no one set rule to determine when a cow is culled. Nonetheless, understanding “average trends” for cows can serve as guidelines and help cow calf producers cull the herd in a timely and effective manner.
There is great variability in the longevity of beef cows. Records kept by a large ranching operation in Florida in the 1980's and published in the 33rd Annual Proceedings of the Beef Cattle Short Course by the University of Florida Animal Science Department, show how productivity changes over the life of the beef cows. These large data sets, (19500 cows, and 14000 cows in two separate years) compared the average percentage of cows determined to be pregnant based on their age in years.
This data would indicate that cows are consistent in the rebreeding performance through about 8 years of age. A small decline was noted as cows aged from 8 to 10 years of age. However the most consistent decline in reproductive performance was noted after cows were 10 years of age. A steeper decline in reproductive performance was found as they became 12 years of age. In other words, start to watch for reasons to cull a cow at about age 8. By the time she is 10, look at her very closely and consider culling; as she reaches her 12th year, plan to cull her before she gets health problems or in very poor body condition.