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Selecting replacement heifers: What are the criteria?

Jordan Thomas and Carson Andersen for Progressive Cattle Published on 24 September 2020

In last month’s issue of Progressive Cattle, we talked about how selection of commercial replacement heifers shouldn’t happen at weaning. That’s because heifers that conceive early in their first breeding season are really the only profitable replacements to keep.

Of course, there are additional criteria to consider when selecting heifers, however. In this article, we will dive deeper into some of the questions producers wrestle with in heifer selection.

Should I consider a heifer’s phenotype at all, or only her genetics?

It is really a false choice to think we have to choose between phenotype and genetic merit. Let’s be clear about what we really mean by the word phenotype. You often hear the word phenotype used to refer just to the visual appearance of the animal. That’s not really correct. That’s a phenotype, but it’s not what phenotype means.

Consider the animal breeding equation of “P = G+E.” Phenotype is the sum total of the genetic effect on ___ and the environmental effect on ___, with environment in this sense meaning everything that isn’t genetic. Phenotype is just the ___; it’s a word we use to talk about whatever it is we observe. In that sense, the pregnancy status of a heifer is a phenotype. A poor disposition is a phenotype. Blindness from a bad case of pinkeye is a phenotype. There is a genetic component to phenotype, and it may be trivial or it may be very large depending on the heritability. There is an environmental component, too.

Sometimes we should ignore the environmental piece and just focus on the genetic piece. That’s why we should ignore some phenotypes when selecting a bull. For example, you should ignore a bull’s actual weight at birth. Yes, ignore the actual birthweight of a bull. That is a phenotype that includes a big environmental effect you don’t purchase when you buy the bull.

You care about the genetic effect – what he actually passes on. In the phenotype of his actual birthweight, that genetic effect is totally confounded by environmental: how old his dam was, what was she fed, what the year was like, etc. If you want to identify a bull with calving ease, focus on the genetic prediction for calving ease. For traits that have expected progeny differences (EPDs), we make better sire selection decisions with EPDs, since EPDs by definition just focus on the genetic piece.

There are other cases in which we care about the actual phenotype, often simply for economic reasons. Sometimes an environmental effect might limit our ability to capture the value of the genetics. If a bull is lame from a random hoof injury, we may not be able to capture the value of his genetics – even if, ironically, he had genetic merit for exceptional feet and legs. Likewise, some phenotypes should inform your selection decisions for commercial replacement heifers.

An environmental effect can keep a heifer with good genetics from being a profitable commercial investment. For example, we wouldn’t suggest keeping a late-conceiving commercial heifer, regardless of her genetic merit. She might just be later-conceiving because she is younger or for any other random reason rather than because of her genetics, but she just won’t be a profitable commercial investment. The scarier side of the same coin is this: Some early conceiving heifers will actually have poor genetic merit. If all you do is keep every heifer that conceives, you are doing single-trait selection based on one phenotype. You can do better than that.

Should genomics play a role in selecting replacement heifers?

Genomic testing is an incredible tool to more accurately assess the genetic merit of animals. Use that tool whenever you can do it profitably. For registered seedstock breeders, you are probably missing an opportunity if you are not genomic testing almost everything. For commercial producers, the question is really at what stage in the heifer development process genomic testing is most profitable. My suggestion is to collect samples from commercial replacement heifer candidates at the time of pregnancy diagnosis. For heifers you would consider retaining as replacements – remember, that’s the early conceiving heifers – use that information to decide which to sell and which to retain. If you have enough early conceiving heifers to choose from, it just makes sense to use a genomic test to identify the best of the best to retain.

Should I just develop heifers to calve at 30 or 36 months old?

We strongly discourage this. It doesn’t put pressure on heifers for early attainment of puberty – and more importantly, it doesn’t pay. We have heard the arguments, but we have never seen a set of numbers where a later age at first calving actually made sense when doing honest cost accounting. Developing those heifers another six to 12 months inflates the development cost for all heifers and can mask other problems.

If you have to spend an additional year’s worth of development costs to get heifers to breed back, aren’t you keeping the wrong kind of heifers? Even if those are just days grazed on cheap forage, that resource could be used more profitably.

Should I just purchase replacement heifers rather than try to raise my own?

The truth is: Most of us shouldn’t be developing our own replacements. Treat your heifer development program as its own enterprise separate from your cow-calf herd. That heifer development enterprise really ought to be profitable in and of itself if you are going to do it. If you can’t produce heifers for cheaper than you can buy similar-quality heifers, don’t develop your own.

You give up some control over the genetics of those heifers, but that may not be a bad thing. You may even be able to buy better heifers than you can raise, bred to calve exactly when you need them to. Our Missouri Show-Me-Select Replacement Heifer Program has been quite popular because of repeat buyers who really get this.

Another way to think of it is this: If you can’t turn the same profit per dollar invested on your heifers as you do on your cows, invest those dollars in your cow herd instead. The acreage, labor and other inputs you are using for your heifer development program could be put to better use.

You may be able to run a few more cows on those freed-up acres, allowing you to wean more calves and spread your fixed costs over more animals. Alternatively, you may be able to extend the grazing season for your cow herd and feed less hay and supplement, lowering your annual cow carry cost. Don’t forget all the other benefits of simplifying your breeding program to just having a terminal focus: You could use growth and carcass bulls, worry less about calving ease, crossbreed, implant all calves, market larger numbers of calves, etc.

Not developing heifers really is something to consider. Your numbers will be different than your neighbors’, though, so it is possible that developing heifers is actually the most profitable thing you do. Do the honest math and see.

Final thoughts

Technologies such as estrus synchronization and A.I. are incredibly valuable, but well-thought-out systems and management practices are even more valuable. At the end of the day, a commitment to select early calving, high-quality replacement heifers is probably the single-most impactful reproductive management practice there is. Be intentional and take ownership of that part of your program. end mark

Carson Andersen is a graduate research assistant with the University of Missouri.

Jordan Thomas
  • Jordan Thomas

  • Assistant Professor
  • Extension Specialist –Reproduction
  • University of Missouri