“Bull shopping?” Andy commented when he saw the catalogues.

“Trying to,” Julia replied with a puzzled glance, tapping a page covered in circled bull images.

“Mind if I take a look?” asked Andy.

Julia slid the catalogue over. “Sure. See what you think of our selections so far.”

Andy was silent for a moment as he flipped through the catalogue. When he finally spoke, he asked, “How much time do you spend looking at EPDs?”

Robert shrugged, “We look at some of the numbers, just not all of them.”

Julia nodded in agreement.

Expected progeny differences (EPDs) are the difference between the predicted average performance of an animal’s future calves and the average performance of the calves from another animal for specific traits. These predictions assume that the bulls or cows being bred are similar and managed under similar conditions. Essentially, they are a prediction of the value of that animal as a parent.

“Here let me draw you an example,” Andy continued, taking out a pen, and drawing two overlapping curves on the back of the catalogue. “Each curve shows the range of calves you might get from Sire A versus Sire B, and there’s a lot of overlap because not every calf turns out the same. The vertical lines are the EPDs — the average you can expect over a group of calves. Even though some calves will have similar weights, Sire B’s calves are expected to average about six pounds heavier at weaning.”

Robert nodded slowly as he leaned back in his chair.

“Those numbers don’t just come out of thin air either” Andy further explained. “They are complex equations built on pedigree information and all of the performance-based results gathered on the animal, its relatives and progeny. we can add genomics information to that mix as well.”

Julia raised an eyebrow. “Alright, I’ve heard that word plenty. What exactly does genomics do?”

“It tightens the accuracy of the prediction,” Andy said. “When a bull has been genomically tested, it’s like giving his ‘genetic credit report’ a high-resolution scan providing a better understanding of which traits the bull carries. The predictions get sharper, especially for younger bulls who don’t have many or any calves on the ground yet. They can also be used to characterize traits that are difficult or expensive to measure, such as carcass traits or feed efficiency.”

He pointed to a bull in the catalogue, “See the G here, it means this bull has a genomically enhanced EPD (GE-EPD). His accuracy is also higher because of it even though he is only two years old. A high accuracy means that the EPD is less likely to change as more data is available, so you can be more confident he will pass those traits on to his calves.”

Genomics is the study of how genes interact with each other and their environment, and how that influences an animal’s phenotype or the observable traits that animal expresses (e.g., coat colour, ribeye area, weaning weight).

Accuracy is scored from 0 to 1 (0-100%) and shows how close an EPD is to an animal’s true breeding value. The more data that is available, the higher the accuracy.  

Robert leafed through the catalogue; his attention now fixed on the data. “Our goal is heavier weaning weights while keeping calving ease in check,” he said. “Let’s put these three bulls side by side. They are all two-year-old bulls of the same breed.”

He circled the chosen bulls and showed them to Andy.

“When looking at the data, it is important to remember that EPDs are comparative numbers, so you either need to compare to the breed average or to another bull,” Andy explained looking at the circled bulls.

“Nice looking bulls, but let’s take a look at the numbers,” Andy said. “Bull A has a weaning weight (WW) EPD of +72, but the low (-5.2) calving ease direct (CED) makes him a risky choice, as this indicates a higher chance of calving difficulty.”  

Bull B offers good calving ease (+5), but only average weaning weight (+55) when compared to Bull C. Bull C has the same calving ease as Bull B, but his calves are expected to wean 15 pounds heavier. That extra weight will add up across a calf crop, making Bull C the more balanced and profitable choice.”

Breed averages are the average EPD values for all animals in each breed for a particular trait. They provide a benchmark to know if an animal is above or below average for that trait within its breed.

Weaning weight (WW) is measured in pounds and shows the predicted average pounds of difference in weaning weight of calves. A higher number indicates heavier calves at weaning.  For example, a WW EPD of +70 means that this bull’s calves are expected to wean, on average, 15 pounds heavier than a bull with a WW EPD of +55.

Calving ease direct (CED) predicts the average difference in ease with which a sire’s calves will be born from first-calf heifers. A higher number indicates easier calving.  For example, a bull with a CED EPD of +10 compared to a bull with an EPD of +1 would have a 9% greater probability of his calves being born without assistance.

“Percentile rank can be a bit confusing,” Andy explained. “A lower number is actually better—it means the bull outperforms more of his peers within the breed. A 30% ranking for weaning weight places him in the top 30% of bulls, meaning his calves are expected, on average, to perform better than calves sired by the remaining 70%.”

Percentile rank shows where the animal ranks for a trait compared to all animals within that breed and is expressed as a percentage.

Julia leaned forward. “What do you mean?”

“You still have to evaluate the bull himself,” Andy explained. “Look at his feet and legs, his structure and how he moves. A bull also needs to pass a bull breeding soundness evaluation (BBSE). Genetics can predict performance, but a bull with poor conformation won’t last long enough to deliver those benefits.”

Robert nodded. “So, it’s not just the numbers on paper.”

“Exactly,” Andy said. “The best results come from matching solid genetics with sound structure and a management program you trust.“

A Bull Choice That Paid Off

After visiting the breeder, checking the bull’s conformation, temperament and pedigree, Julia and Robert made the trip to the bull sale and brought home Bull C— knowing both the numbers and the structure were right and met their goals.

That spring, the difference was noticeable right away—calves were born easily with fewer late-night checks, they were vigorous and up nursing quickly. By branding time, the added growth was already obvious. By fall, the results were undeniable: their average weaning weight had increased by 15 pounds, bringing them closer to their breeding goals.