One of the biggest costs on a cow-calf operation is cow herd depreciation. For most of us, even if we are not aware of it, cow depreciation is our second-highest expense after cow herd maintenance. It is a problem often ignored because cull cows generate cash flow, but having cows drop out of the cow herd before they have paid for their own development or purchase cost is a losing proposition. For this reason alone, many people would argue we have to select for longevity. However, just as with every other trait, the problem with single-trait selection is that it comes at a cost.
One of the primary ways we have selected for this trait in the past is to wait. We buy bulls out of old “proven” cows. In the meantime, we often give up a lot of progress on other traits while we wait. If a 15-year-old cow had a bull calf when she was two, that bull likely had similar genetics for longevity as the bull she produced when she was 15.
Her genetic makeup and thus her contribution to her offspring will remain unchanged. In fact, depending on how that cow was mated, the calf she had at two years may have carried even more longevity genetics than the calf she had at 15. By waiting 13 years, we have forgone the use of her genetics at an earlier stage and have also frozen our progress on other traits in time. Additionally, there may be discussion about what is the age where a cow becomes “proven” for her staying power.
One of the ways we can tackle cow depreciation is to drive down the cost of producing replacement females. This may involve picking and choosing which tactics we use to develop those heifers and get them in calf, but also how to get them rebred. If it costs $2,000 to bring a heifer into production, and she sells open for $1,000 then her rate of depreciation will be drastically higher than if it only costs $1,000 to get her bred and she sells open for the same price. Picking and choosing management strategies to bring heifers into the herd may involve tradeoffs, and optimum may not be a 100 per cent conception rate if the cost to achieve it is too high.
Sell before they depreciate
Another way to tackle depreciation is to sell cows before they have depreciated, although admittedly most of us struggle with selling cows in the prime of their life. A third option may be buying slightly used cows. In other words, a three-year-old bred cow may be less expensive than that fancy bred heifer and will tend to have a much lower fallout rate than heifers that have to calve and rebreed at age two.
In our cow herd and many others, one of the best ways for a cow to stay in the herd is to be “average and pregnant,” however over time if we are doing a job of selection, that cow had better become “below average” or we are making no progress or perhaps falling off in achieving our other goals. In other words, as a group my replacement heifers each year should be slightly better than the year before. I use the term “as a group” because there are certainly individual animals that may be outliers.
This brings us to one of the challenges with assessing longevity on an individual animal basis — sheer luck. There are many reasons why a cow might leave the herd, ranging from the fairly standard “open in the fall” to the more complex such as “needed money for a payment,” or “she was hit by lightning.” If a bull gets a bad case of foot rot, the longevity of the cows in that pasture can suffer through no fault of their own. You can see that all of these reasons may impact the length of time a cow stays in the herd, but many of them have nothing to do with her genetics for long-term productivity.
In genetic selection, the large potential for outside influences is shown by the low heritability of fertility and maternal traits. Typically, fertility traits are at best only half as heritable as traits such as growth and carcass. This does not mean that collecting data and genetic evaluation don’t work, it just means that a lot of chance and environment is involved.
In order to overcome a low heritability and make progress on longevity means we need lots of data on large numbers of cows in a cow family. Fortunately, with the advent of newer DNA SNP testing (SNP stands for single nucleotide polymorphisms) we can get a lot more accurate analysis a lot more quickly. Since phenotypic observations of longevity involve a lot of DNA interacting with several environmental influences, being able to look directly at the animal’s DNA allows us to circumvent some of these environmental challenges.
In fact, one of the evaluations I am currently working with shows that using a DNA test to examine sustained cow fertility has the equivalent power of recording 22 progeny records from that same cow. The difference: DNA can be collected and assessed before we ever make a decision to breed that heifer in the first place, rather than waiting for her to have 22 calves.
DNA can also be collected on bulls that will be used to produce females. While we still need data on cow fertility and if cows remain in the cow herd, the ability to accelerate the selection process for the trait that takes the longest to measure of all the traits is important. Having some degree of accurate selection for longevity at a young age in the seedstock population lets us make progress in other traits while also transmitting that longevity into the commercial industry.
Breeding beef cattle is a slow business. If the generation interval of a beef animal is roughly seven years, the generation interval for a cow herd selecting for longevity is much longer — potentially 10 years or greater. In the meantime, we may forgo years of progress in other traits, and worse our competition such as pork, poultry and plant protein are turning a lot of generations while we work on a single generation of beef cows. If the potential exists to make a two per cent improvement with each calf crop towards an overall goal, holding off on this progress in search of longevity of say 10 years, represents a potential 20 per cent loss of progress towards a broader cow herd or industry goal.
It is always interesting to engage in discussions around whether EPD and selection tools work or not, and I would argue that these tools are highly effective at changing cattle. EPD, particularly when coupled with DNA technology, provide the most powerful tool we have to effect change in cattle today. The argument ensues as to whether the direction of the change and the traits we are working on are the right ones. Longevity is important, and I still like to look at that “good old cow” that has paid her way, but I don’t think the industry can always afford the patience to reproduce her in the low accuracy and slow manner of the past.
I would encourage you to take a look at your cow herd records over the winter and really try to get a handle on what cow herd depreciation may be costing you. It is an interesting exercise that can certainly challenge your management focus.