Ask the Vet

Heifer Selection By The Numbers

Wondering which heifers to keep as replacements? Here's how Dr. Ken McMillan makes that call.(Progressive Farmer photo by Sam Wirzba)

Question: I'm expanding my cow herd and retaining my own heifers. I can only keep about 30% of my heifer crop because of pasture availability. What is the simplest, cheapest way for me to decide which 30% to keep before I've spent a lot of money developing them?

Answer: For this discussion, I will assume all the heifers are by one bull and not discuss how multiple sires might factor into your selection decision. I will remind you that 50% of the genetics comes from the bull side, and bull selection is your most significant path to cow herd improvement. The bull has 25 to 30 times the significance of a single cow.

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With that understanding, when it comes to heifer selection, every person has his or her own opinion about what works. For me, I always start by looking at mama. A replacement heifer's dam should be a rock-solid cow. She should have good eyes, feet, legs, udder and the right disposition. In fact, I usually start with disposition. She also needs to be the right size for your environment, your operation and your goals. She needs to have adequate muscle, bone and capacity, but retain a feminine appearance. And she should be a cow that maintains good body condition all year long and breeds back early in the breeding cycle every year.

Next, I look at the heifer. I prefer heifers born early in the breeding season—and not just because they are often larger. Rather, these heifers will be older and more mature at breeding. I think it is also an indicator her cow family is more fertile.

I like to wait until at least a month after weaning to see how the calf does off the cow. But I also note heifers that are too fat or too thin at weaning. Those that are too fat will often not be good milkers as cows. Thin heifers may not cycle and breed well, and may have dams that are poor milkers.

I also consider many of the same criteria I use for cows, especially disposition and conformation. It never hurts to have another set of eyes to look also. Your Extension agent or veterinarian, a consultant or experienced and successful cattlemen can give you valuable insight.

I believe data is your best friend in making these choices. Our eyes and heart can lead us down the wrong road. Birthweights, calving ease scores, hip height and adjusted weaning weights are easy numbers to collect, and they are a solid foundation on which to build your choices. The more data you can collect and the longer you collect it, the more powerful it becomes.

If you retain ownership of steers and cull heifers, or can track the data from the rail, this can become a very powerful tool. Ultrasound can also generate some valuable data.

Genomics, or gene testing, is rapidly becoming a powerful and affordable tool, accessible to more and more operators each year in terms of expense. Combined with what you already know about your heifers, this can help you make a final cut.

(SK)

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