Cow-Calf Commentary for Iowa Cattleman Magazine

By Randie Culbertson, extension cow-calf specialist and Shelby Gruss, Extension Forage Specialist

June 2024

What’s the big deal about cow longevity?
June is a critical time for spring calving herds. For most herds, calving has wrapped up, pairs are going out on grass, bulls are turned out, and breeding season begins. A cow's ability to breed during a limited breeding season is crucial for her to remain in the herd. Reproduction and cow fertility are the most economically significant traits for cow-calf operations. Cow longevity has the largest impact and is estimated to be 3 to 9 times more profitable than other production traits.

First, let's define cow longevity. Longevity is a measure of how long a cow remains in the herd. Reproductive failure is the most prominent reason cows are culled from the herd and is typically perceived as a fertility trait. Longevity represents the ability of a cow to maintain an annual calving interval, remain sound, and stay healthy.

Why is cow longevity such an influential trait for profitability? Research has shown that a cow must reach six years of age, assuming she has calved as a 2-year-old and provided a calf each year, to reach an economic breakeven point. This breakeven point accounts for recouping the cow's cost for development and annual maintenance as well as compensating for cows who prematurely failed to remain in the herd. Examining the age distribution of a cow herd can help a producer discern the reproductive efficiency and possible areas of economic loss for an operation. In addition, looking at pregnancy rates and calving distributions by cow age also can help to identify potential areas of lost reproductive efficiency. For example, if a large number of cows are being culled after their first calf, it may be time to reexamine how first-calf heifers are being managed.

In addition to considering the development and maintenance cost of cow development, she will produce heavier calves as she ages. Some traits of the calf are affected by the age of the dam. Heifers typically have smaller calves than those they will produce as a mature cow. From 5 to 10 years of age, cows are in their production prime, producing their heaviest calves. The age of a dam is important to remember when selecting replacements so you don't penalize a calf from a young heifer that may be smaller than a calf from an older, more mature cow.

Typical weaning weight adjustments also include an adjustment for the age of the calf's dam. The age of dam adjustment is dependent on the sex and breed of the calf. Depending on the breed, a heifer could have calves that are 50 to 60 pounds lighter compared to her calves when she reaches maturity. There is a point when an older cow, typically older than 10, starts to produce lighter calves compared to when she was younger. Although the calf performance is less than when the cow was younger, these older cows have paid for themselves, and their calves are "free and clear." If the cow is healthy and in good shape, keeping her in the herd is worth considering even if her calf performance has fallen off some. There is always a point when a cow becomes too elderly to remain in the herd, and it becomes time to cull her. Age of dam effects are typically only seen on traits expressed early in a calf’s life. There are little to no maternal effects for traits such as yearling weights and feedlot performance.

Although cow longevity has a sizeable economic influence on cow herd performance, it is a challenge to select for. First, it is a trait measured late in life for a cow with few early life indicators. As a result, there is a significant investment in a cow that may fail to reach an age to recoup her cost of development and maintenance. In addition, cow longevity is a lowly heritable trait. A lowly heritable trait indicates a sizeable environmental influence on the expression of the trait. For cow longevity, it isn’t surprising that the management would greatly influence a cow's ability to remain in the herd.

The important thing to consider is that the heritability is not zero, and genetics still matter! Genetic selection for improved cow longevity in a herd is possible but the rate of improvement is slower compared to traits with a higher heritability. Expected progeny differences (EPD) for cow longevity are typically reported as stayability, but the American Angus Association is working on releasing its functional longevity EPD. These EPDs report the probability of daughters remaining in the herd to a specific age, typically to 6 years of age.


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