Cattle genomics: sire selection tools for breeding more productive, profitable cows


Cattle genomics: sire selection tools for breeding more productive, profitable cows

September 19, 2022

When we think about what makes a commercial cowherd exceptional, we must remember the long-term role that effective sire selection plays.

Editor’s note: first published: Cattlemen’s News Magazine

Getting the bull buying decision right is critical to the long-term success of a transaction. This decision affects not only the calf production the bull has throughout its life, but also the performance of successive generations when replacement females are kept. Long-lived females are the cornerstone of a profitable commercial operation, so it’s important to identify bulls that will produce fertile females, said Dr. Troy Rowan writes.

A commercial cow usually does not turn a profit until it is six years old. Only then did he recoup the costs of its development and maintenance. We know that developing heifers properly isn’t cheap, so cows that haven’t heard before this profitable age are likely losing money.

Since cow longevity is a very important trait and bulls are the main driver of genetic progress in a commercial herd, having EPD-based selection tools for cow performance is essential for long-term genetic improvement. Predicting a bull’s genetic ability to produce long-lived daughters allows us to better appreciate the “big picture” he provides to the herd.

Many breed associations report cow longevity EPDs. The most common measure is staying power (STAY). STAY EPDs can be interpreted as the difference between sisters in the percentage of daughters that will remain in the herd until the age of six without missing a calf. For example, if Bull A had a STAY EPD of 20 and Bull B had a STAY EPD of 30, we would expect 10% more of Bull B’s daughters to remain in the herd at age 6. The results of using STAY in practice are surprising. An American Simmental Association analysis showed that daughters of bulls in the top 25% of the breed for STAY were twice as likely to remain in the herd at six years of age than daughters of bulls in the bottom 25% of the breed. Daughters of high STAY (top 25%) litters produced an average of two more calves during their reproductive period than daughters of low STAY breeds.

Sustainability is a complex property, meaning it consists of many other individual component properties. All the reasons we can think of to wean a cow early from the herd translate into STAYING: fertility, structural health, udder quality, temperament, mothering ability, and other traits. Many breed associations directly report EPDs for individual cow-centric traits. This allows selection of important female traits in breeds without STAY EPDs, as well as specific components of overall longevity that a particular herd may need.

For example, we may find that our herd is suffering from foot and leg problems, which causes us to cull otherwise fertile and productive four- and five-year-old females. The American Angus Association reports EPDs (smaller EPDs = more favorable phenotypes in both cases) for Leg Angle and Claw Set, which can allow us to more accurately identify bulls that will pass structural health on to their offspring.

A seed producer and friend in Tennessee told me that the way we’ve historically talked about these cow traits has missed the mark. For a long time, these were branded as “comfort features” based on their potential to reduce the labor involved in a particular cow. While more comfortable cows are certainly nice, it is clear that productive, economical, healthy, docile and productive cows are central to commercial cow-calf profitability. These female-directed traits have intrinsic economic value and are the basis of commercial herd success. So we started calling these “core features”.

Each of these traits affects the overall profitability of the sire when the producer keeps replacement females. Balancing these traits can be a handful when trying to make genetic progress on other profitable traits (ie, weaning weight) at the same time. Each feature contributes to the overall profitability to varying degrees. Some of these traits are genetically linked in favorable (e.g., stamina and structural health) and unfavorable (e.g., weaning weight and mature cow weight) pathways. Breed associations have worked to develop economic selection indices that determine the weighting of multiple traits according to their relative economic importance in the overall production system. The result is a single value that can be interpreted as an “EPD for profit” that takes into account many economically relevant characteristics. Indexes can be parent, terminal, or composite centered.

For producers who wean calves and keep replacement females, maternal indicators are ideal because they place great emphasis on cow-based foundational traits and maintaining weaning performance. Before using it, it is important to understand the component properties that make up an index. While I won’t go into detail about the individual indexes, I will note that the breed association websites do a great job of describing the production scenarios their indexes are intended for and the features included in the index.

Using a mother-oriented index along with EPDs, a key trait to select bulls, can focus your operation on selecting the most important trait: Profit! The genetic tools I discuss here take the guesswork out of selecting bulls that will produce daughters that will keep our herds profitable and successful for the long term.

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