Did you know yearling weight is one of those phenotypes that tends to fall off when it comes to reporting? Seedstock breeders do a great job getting birth and weaning information submitted, and then life sometimes gets busy. For the majority of operations, they are in the midst of calving when those yearling heifers need to get weighed. Bulls sold for breeding stock do tend to get weighed because that information is expected for the sale catalog, while heifers can be much easier to overlook unless weighing them is intentionally planned out and on the calendar.
Now that you have that context, instead of solely focusing on YW EPD, we’re going to talk about what we’re leaving on the table at the seedstock level by not reporting yearling weight, and as a commercial breeder, what’s important for you to know here.
So…why does yearling weight matter when we already have a weaning weight? What happens between those two weights gives the genetic evaluation information about the post-weaning growth.
Let’s dig into Yearling Weight and Post-Weaning Gain, shall we?
As defined by American Angus Association a YW EPD: expressed in pounds, is a predictor of a sire’s ability to transmit yearling growth to his progeny compared to that of other sires.
As defined by American Simmental Association Post-Weaning Gain: genetic differences in growth after weaning.
The following is sourced from the Beef Improvement Federation (BIF): YW EPD is a reflection of both pre-weaning and post-weaning growth for that animal. The greater the yearling weight EPD, the more growth potential that animal has to pass to its offspring. Yearling weight is also sometimes used as an indicator trait for other EPDs such as Mature Weight.
Yearling weight windows vary by association, most notably, Angus at 320-440 days of age and Simmental at 330-440 for your planning purposes.
Seedstock breeders…the message for you don’t quit weighing after weaning, especially the females! Make sure to account for contemporary groups, i.e., if from weaning to yearling if they were developed differently, indicate that by assigning a group number. That yearling weight also provides the evaluation with another benchmark. We knew where that calf was around weaning, now we’re learning what happened during the post-weaning period as well. If we only capture the standouts, we’ve taken away much of the information the evaluation needs to identify genetic differences within the group for this time period, especially as it relates back to comparing sires.
Now, skip ahead, read the commercial section and then come back here. This is exactly why I’ve been harping on seedstock clients to collect mature cow weights and BCS. We know growth and mature size are related. If we collect the actual mature phenotypes, we’re giving the evaluation more information to help better identify cattle that bend that relationship (hence the term curve-bender). Having the actual mature cow weight records helps us identify the cattle that deviate from the “expected” relationship.
Side note: If you weigh your cows, do it within 45 days of weaning and collect a BCS at the same time. This information provides the evaluation with additional context around that cow’s weight and condition.
Commercial cow/calf operators…this section is tailored for you.
Post-weaning growth doesn’t exist in a vacuum. ASA reports a strong positive relationship between YW and MW EPD. In other words, cattle genetically inclined toward more yearling growth also tend (on average) to become heavier mature cattle. Key words there being “on average”, right? The relationship isn’t perfect, nothing is, but there is a strong correlation there. If we’re selecting bred heifers and there isn’t a MW prediction available, WW and YW can still give us some information about where mature size may be headed because of those genetic relationships. This is where your specific breeding objectives matter. If you’re retaining ownership through the rail, YW and PWG become increasingly important. If you’re building replacements, we also need to consider what pushing growth may ultimately mean for the females we’re creating.
Key take aways:
For seedstock producers, turn in yearling weight data. Your association will thank you, but most of all it provides the evaluation with more information about post-weaning growth and ultimately strengthens the genetic predictions available to your customers.
Collecting the phenotype information on an animal is always encouraged if you can. An actual record from that animal and its contemporary group gives the evaluation insight into how those genetics performed in a similar environment and strengthens the information represented in the population from your herd, yes, even if a genomic profile is on file for the individuals.
Commercial producers, we usually don’t get to have our cake and eat it too. Growth and mature size are genetically related, so if we keep pushing growth without monitoring the rest of the genetics package, other pieces tend to move with it. That’s where finding your sweet spot matters. In our own maternal herd, we’re not chasing maximum growth. We want enough growth while also ensuring we’re retaining the maternal components needed to build a moderate frame female which best fits our environment and available resources. In our Terminal herd? Totally different job description for those big bad boy bulls. There we’re running a moderate female while selecting bulls for top percentiles in growth along with carcass merit ($TI or $B/$W/$F indexes anyone?) because those calves are being designed specifically to perform well in the feedlot and on the grid.
Breeding with purpose and intention.
Same EPDs Different objectives Selecting for optimums
Disclaimer: I’m not a geneticist. The information above is compiled from breed association resources and translated into practical terms based on my understanding and application of these tools.
