Genetics Record-Keeping - Level 2

This module has been designed to build upon the information covered in Genetics Record-Keeping Level 1. If you have completed the previous module, you may have already identified the areas of your operation where you would like to improve and have set some production goals. While some of these goals will be influenced by your production practices (e.g., feed, breeding season), other goals, such as higher weaning weights, will be influenced by both genetics and environmental factors (i.e., stress, health status, weather).

Genetic change in cow-calf operations can be achieved through both sire selection and replacement female selection combined with cow culling. Sire selection is often considered the fastest method of genetic improvement as a single bull contributes genetics to many calves in a single breeding season. Replacement heifer selection offers a second avenue for long-term genetic progress through retention of superior females to incorporate desirable genetics in the herd. At the same time, culling cows with undesirable characteristics (i.e., poor reproductive performance, structural problems, poor maternal traits) removes less favourable genetics from the herd.

Genetics Dictionary

What is Heritability?

Heritability tells us how much of a trait is controlled by genetics versus the environment and/or management. It’s expressed as a number between zero and one:^1,2

• High heritability (over 0.40): Traits are strongly influenced by genetics, meaning you can make changes more quickly by selecting the right replacements and bulls. Examples: ribeye area, marbling, weight and growth traits.
• Moderate heritability (0.15 to 0.40): Traits that can be improved through both genetics and management. Examples: milk production and calving ease.
• Low heritability (less than 0.15): Traits are mainly influenced by crossbreeding (e.g., heterosis/hybrid vigour and management (e.g., nutrition, colostrum, vaccination). Examples: fertility, reproductive efficiency and disease resistance.

Weaning weight has a heritability of 0.24 to 0.30, which means that 24% to 30% of the differences we see in weaning weights between cattle in a herd are caused by genetics. Table 1 provides a summary of the heritability of common traits. The higher the heritability, the more progress you’ll make through selection. Traits with low heritability still matter — they just require dedicated management to go along with genetic decisions.

As an example, improving pregnancy rates in beef cattle cannot be achieved through genetics alone. This is primarily due to fertility traits having low heritability and being heavily influenced by management factors such as nutrition, body condition, health and breeding season management. Until those areas are optimized, selecting new genetics alone won’t move the needle.

In contrast, calving ease is moderately heritable, and information can be used strategically when planning a heifer breeding program. Selecting sires with high calving-ease genetics can help avoid calving difficulties.

Table 1: The impact of genetics or management changes on culling decisions

Trait Correlations

Traits don’t work in isolation. Selection for one trait can cause an increase or decrease in the expression of another, sometimes in ways you don’t want. Trait correlations are expressed as a number between +1 and –1.

A positive (+) genetic correlation means that as one trait increases, the other also tends to increase. A negative (-) correlation means that as one trait increases, the other tends to decline. Despite the positive/negative labels, neither automatically indicates whether the relationship is beneficial. A correlation is considered favorable when selection for one trait leads to a desirable change in another³.

Expected Progeny Differences (EPDS)

Expected Progeny Differences (EPDs) are estimates the genetic merit of that animal as a parent. At their core, EPDs are the difference between the predicted average performance of an animal’s future progeny and the average performance of progeny of another animal for specific traits. They do not predict individual performance or weights.

EPDs can help beef producers to strategically select bulls or replacement heifers with traits that support operational goals.

To compensate for differences in environment and management, contemporary groupings are used when calculating EPDs. Contemporary groups are animals of the same age and sex raised under the same management conditions. Once these factors are accounted for, the genetic component is the part that remains, and that is what EPDs predict.

Because EPDs rely on producer-provided information, accurate data are critical. This means reporting all performance data measured on all animals in the herd and correctly identifying contemporary groups under different management (for example, if one group received creep feed and one group did not). In addition, billions of genetically different progeny are possible from just a single mating! There are plenty of genetic differences between full siblings. Because EPDs predict AVERAGE progeny performance, it is quite common to have a calf or two that doesn’t fit in with the rest. This is where accuracy comes in.

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. Adding data on an animal’s own performance, the performance of its relatives- and performance of its progeny will increase accuracy.

• A high accuracy means that an EPD is less likely to change as more data is available, so there is greater confidence an animal will pass those traits to its calves. Proven artificial insemination (AI) sires with high number of progeny and / or genomic data will have higher accuracy values.
• Low accuracy values are common for younger animals, where progeny performance is unavailable. These EPDs have a greater likelihood of changing over time.

Some breed associations are incorporating genomic data into their EPD evaluations. By merging DNA test results with the traditional EPDs, more information can be added at a younger age, increasing the accuracy (and confidence) in that animal’s EPDs.

Although all these numbers can be confusing, selection based upon a single trait can often lead to undesired consequences. For example, selecting only for weaning weight in a production system where heifers are retained will lead to larger mature cows, potential calving difficulties, and perhaps increased feed intake. A balanced selection approach focusing on optimizing traits for your environment and production system works much better than trying to maximize a single trait.

Download the EPD Interpretation Guide

Selection Indexes

Selection indexes help simplify genetic decisions by combining several traits into one value that reflects your breeding goals while also accounting for trait correlations behind the scenes, making it easier to avoid unintended trade-offs and helping prevent single-trait selection. Think of a selection index like a financial index: instead of tracking every single trait (or “stock”) on its own, the index combines them into one value based on their economic importance.

Like expected progeny differences (EPDs), indexes are breed-specific, so they cannot be compared across breeds, unless the genetic evaluation contains information from several breeds. Knowing which indexes fit your operation can make bull buying simpler and more profitable.

While indexes are extremely useful, they should be used alongside visual appraisal, structural soundness and good management to make the most informed selection decisions.

Selecting Replacement Heifers

The decision to raise or purchase replacement heifers will vary based on the management and economic goals of each operation. If you have been collecting and analyzing records to this point, you may already have already set breeding goals which will define which characteristics you need to be looking for in your replacements.

Some criteria to consider for raising and purchasing replacement females:

• Birth date? How old do you need heifers to be to fit into a front-loaded calving system?
• What breed composition will work with the bulls you are running?
• How has her dam performed?
• How has she performed herself?

The Replacement Heifer Calculator estimates the costs of developing a replacement heifer from weaning, through breeding and preg-checking.

Data to record or request from seller:

Example:  

From your records, you have identified achieving higher weaning weights as one of your production goals. From your current calf crop, you want to select the heifer calves that will have the best chance of producing calves with higher weaning weights. To do this, review the weaning weights of your cows and their progeny, and select animals that are in the top for weaning weight and were born in the earliest calving groups.

Example goals:

• Link heifer performance data to their dams for the next calf crop
• Use dam performance as a selection criterion when selecting the next group of replacements

Selecting Replacement Bulls

Eighty-seven percent of the genetic makeup of the current calf crop is influenced by the sires used over the past three generations. Purchasing the best bull for your operation starts with good record-keeping to identify your operation’s strengths and weaknesses. From there you can work to narrow down your search based on your breeding system, genetic goals and budget.

How much is a good bull worth to you? The BCRC Bull Valuation Calculator can help you estimate the value and breakeven price of a herd bull based on your farm’s data to identify what sire best fits your budget and herd goals. This easy-to-use tool simplifies the complex process of deciding a bull’s worth and can ultimately help improve your bottom line and the genetics of your beef cattle herd.

Breeding programs will be determined by operational goals and the management practices that fit those goals. A farm that sells their calves at weaning may choose a crossbreeding program with high performance, while a farm that direct markets their beef may prefer a single breed in order to ensure consistent carcass quality.

There are many different types of bulls available, so aiming for complementarity of the bull’s genetics to your cow herd’s genetic makeup and fit with your operational goals will contribute to increased revenue and reduced costs.

Given the plethora of EPDs available, trying to sort through ten or twenty individual EPDs that may not have relevance to your particular operation can easily lead to information overload, so many breed associations provide selection indexes that combine multiple traits with relevant weightings in order to combine several traits of interest into one number.  By focusing on Economically Relevant Traits (ERTs), you can eliminate those bits of information that will not directly impact your operation’s profitability. Economically relevant traits are those that are directly associated with a source of revenue, or a cost.  Not all EPDs represent ERTs – instead they use a related (or indicator) trait to estimate the ERT.

Here are seven essential stops along the road to purchasing your next herd sire.

Example:  

From your records, you have identified achieving higher weaning weights as one of your production goals. This time, focus on selecting bulls to breed to the mature cow herd with strong EPDs for weaning weights, since these traits are moderately heritable.

Example goals:

• Select bulls for the next breeding season with optimal EPDs for weaning weight

Using Record-Keeping for Cow Culling Decisions

The number one factor impacting cow profitability is whether she successfully produces a calf every year. Other factors such as conformation, milking ability, health issues and temperament can also impact profitability year by year. Cows with impaired mobility or unsound mouths are unlikely to intake sufficient nutrients to maintain body condition and be productive. Additionally, newborn calves may have difficulty nursing from large teats or pendulous udders.

Using records to quickly identify cows to be culled can save a lot of time and effort. On some operations this may be as simple as putting a cull tag in the animals ear or adding an asterisk* beside her identification in your records. Identifying some of your non-negotiable traits can also help with making culling decisions. For example, some of the traits listed in Table 1 may be non-negotiable for you.

If the goal is to reduce certain issues in your herd, the problem may not be solved using only genetics. There can be confusion as to whether an issue primarily has a genetic component or requires different management. For example, udder conformation (teat size and suspension) is moderately heritable and primarily improved through genetic selection, while calving interval has a very low heritability and is influenced most by management. Some traits, such as temperament, are influenced by both genetic and management components.

Some common traits used in making culling decisions include:

• Cow traits such as udder conformation, temperament, milking ability and foot conformation
• Fertility traits such as maternal ability, calving interval or vaginal prolapse
• Calf performance such as birth weight, weaning weight, feed efficiency and carcass traits

Example: 

You need to decide which heifers to keep from your calf crop as replacements. In your records you have put an asterisk beside two cows that both had equally well-performing heifer calves this year. Your notes indicate that one cow had vaginal prolapse this past year before calving, the other cow you marked as treated for foot rot. Since vaginal prolapse is considered to be a heritable trait you decide not to keep the heifer calf from the first cow. Since the foot rot is more of a management issue, you decide to keep the heifer calf from the second cow.

Example goals for next year’s calving season:

• Link all calves born each year to their dams with specific identification
• Apply a cull tag to all cows with poor udders at calving
• Apply a cull tag to all cows who were aggressive or hard to handle at calving

References:

1. Rolf, M. (2015). Genetic Correlations and Antagonisms.
2. Koots, K. R., Gibson, J. P., Smith, C., and Wilton, J. W. (1994). Analyses of Published Genetic Parameter Estimates for Beef Production Traits – Heritability. Anim. Breed. 62: 309-338 (Abstr.).
3. Beef Improvement Federation. (2010). Guidelines for Uniform Beef Improvement Programs.

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Acknowledgements

Thanks to:

• Canadian Beef Breeds Council (CBBC)
• Alberta Beef Producers (ABP)
• Saskatchewan Ministry of Agriculture
• Maritime Beef Test Station
• University of Guelph

for their time and expertise in review of the contents of this page.

This content was last reviewed September 2026.