Planning, Self-Evaluation Are Key To Successful Sire Selection

For many North Dakota cattle producers, winter and early spring is prime bull-buying season. Considering that a single bull may sire a few to hundreds of calves, depending on an operation's breeding strategy, the impact of the bull on the genetic basis of the herd cannot be ignored, says Lacey Quail, North Dakota State University Extension livestock management specialist at the North Central Research Extension Center.

Selecting sires that complement a cow herd and contribute to the goals of the operation, both genetically and phenotypically, is of the utmost importance, says Quail. However, the large amount of performance data that is available to buyers can make selection decisions difficult.

Before sale day, Quail recommends buyers take time to consider their priorities and set some goals for their operation. Answering questions related to how calves are marketed and how replacement females are acquired will go a long way in identifying a bull that will benefit the operation.

For example, if a rancher retains replacement heifers, they will likely want to select sires that contribute maternal traits to calves; however, if all male and female calves are marketed, maternal traits will likely be less significant to the operation.

Additionally, producers should consider their production environment and how it may support or limit the genetic potential for any particular trait. For instance, pounds of weaning weight due to milk production is often considered in sire selection. However, milk production requires feed inputs. If the production environment does not support additional milk production, it may be unrealistic to emphasize that trait as significantly in sire selection.

When looking through a sire directory or sale catalog, it is important to know what EPD and ACC stand for. Expected Progeny Difference (EPD) and Accuracy (ACC) are key to understanding which bull may fit the operation. An EPD is a prediction that combines the individual genetic potential of a particular bull and the genetic potential of existing relatives to that bull (such as sire, dam, progeny and siblings).

An EPD can be either positive or negative. For example, a bull with a birth weight EPD of +7 would be expected to sire calves that are 7 pounds heavier, on average, than a bull with birth weight EPD of zero within the same breed. A bull with a birth weight EPD of -5 would be expected to sire calves that are 5 pounds lighter, on average, compared to a bull with a birth weight EPD of zero within the same breed.

Accuracy is a measure of reliability or how likely it is that an EPD may change as more relatives of that bull get added to the system. Simply put, the more data points (relatives) for which there is data, the more certain (accurate) a producer can be that an EPD will not fluctuate as more progeny are added. An EPD with an ACC of 0.9 is expected to change very little (90% accurate), while an EPD with an ACC of 0.7 or below may change more drastically as progeny data are added.

Quail says it is important to note that not every trait is measured in the same units. Weight traits (such as birth weight, weaning weight and yearling weight) are measured in pounds. Scrotal circumference is measured in centimeters. Rib-eye area is measured in square inches. Calving Ease Direct (CED) is measured as the percentage of unassisted births when mated to 2-year-old heifers. This information, along with other abbreviations, is listed on a breed association's website and often in sale catalogs.

Take two bulls, for example: one with a CED of 15 and another with a CED of 10. The bull with a CED of 15 is expected to have 5% more unassisted births compared to the bull with a CED of 10 in 2-year-old heifers. Where CED is concerned, a higher value indicates greater calving ease.

Someone selecting a new herd sire is likely to look for a bull that excels in multiple areas, not just one. Considering the number of EPDs they may want to prioritize and the correlations that exist between genetic traits, sire selection can quickly become overwhelming. An economic selection index may be helpful to consider here. A selection index includes multiple individual EPDs and gives an overall economic value associated with those traits as a single dollar value; however, it is important to consider which individual traits are included in an index and if they are important to current goals. Additionally, the individual traits in an index are not weighted equally when calculating an index value, so two bulls may have the same index value while having different values for individual EPDs.

Depending on the operation and their goals, a selection index may be used as a first criterion to identify sires within a breed that warrant a closer look. Individual EPDs can then be used to fine-tune the selection process to make the most genetic progress toward the operation's goals. For example, if a preweaning growth index value is high, but upon further investigation, the individual weaning weight EPD is not favorable to the operation's goals, that bull may not be the best fit. Like EPDs, a selection index should only be used to compare sires within the same breed.

To complement genetic merit, Quail says to evaluate phenotype when buying a bull.

"Conformation, feet and leg structure, muscling and frame are important to the breeding success of a sire," says Quail. "These phenotypic traits, along with the udder structure of a bull's dam, can indicate lasting impacts for your herd."

The marketability of calves, soundness and performance in the feedyard and the long-term functionality of any females that are produced by a sire are to be seriously considered when it comes time to purchase a new herd sire.

Inevitably, says Quail, there is no one-size-fits-all bull.

Instead, producers should balance their operation's priorities when it comes to opportunities for income (such as weaning weight, carcass weight, ribeye area and marbling) with opportunities to improve longevity and reduce expense (such as stayability, heifer development/pregnancy, feed efficiency, docility and structure).

Knowing how a herd is currently performing, as well as being realistic about the areas that need improvement will help tremendously in finding a bull to help bridge that gap, concludes Quail.