Selecting for Fertility in Cows

Fertility is the foundation of cow-calf income, since the herd runs on one calf per cow per year. It responds slowly to selection, so records and steady culling decisions matter.

Key points

Fertility drives income in a cow-calf herd.
Simple records of calving date, calf survival and pregnancy status are enough to start.
A defined breeding season makes culling easier.
Bull soundness exams and good nutrition protect fertility.
Call the vet quickly for abortions or unexplained breeding failure.

Why fertility comes first

A cow that does not breed on time produces no calf for the year, but still eats feed. Weaning weight, carcass merit and every other trait are irrelevant if the cow is open.

Fertility has low heritability, which means environment and management explain much of the variation, but selection and culling still make a difference over time.

A cow that calves early in the season also has more time to recover and rebreed, and her calf is older and heavier at weaning. Early conception compounds over her whole life.

What to record

The most useful information is simple. Record each cow's calving date, whether she was assisted, calf survival, weaning weight and whether she was pregnant at the end of the breeding season.

Over several years, the pattern shows which cows breed early, calve in the first part of the season and wean a calf every year. Those are the cows to keep daughters from.

Calving date for each cow every year
Open or bred status after pregnancy checking
Calf survival to weaning
Assisted calving notes
Body condition scores at key times

Heifer fertility and the bull's role

Heifers that reach puberty early and conceive early in their first breeding season tend to stay productive. Many producers keep replacements from cows that calved early in the season and use bulls with favorable heifer pregnancy EPDs, where the breed provides them.

Bulls influence fertility too. A breeding soundness exam by your veterinarian before the season checks the bull's physical soundness, semen quality and scrotal measurement. Scrotal circumference EPD in a bull relates to the fertility of his daughters in several breeds.

If your herd has several bulls, record which bull bred which group. Differences in pregnancy rate between bulls usually point to a soundness or libido problem worth discussing with your vet.

Using a defined breeding season

A limited breeding season is itself a selection tool. Cows that do not conceive within the window are open at pregnancy check and can be culled. Without a window, late and open cows blur together in the herd.

Choose a season that matches forage, and stick to it. Keep your calving group tight so calf age and weight are consistent.

Set start and end dates for breeding
Pregnancy check after the season ends
Cull open cows unless there is a clear reason
Keep records of late-calving cows

Nutrition and condition

Cows in poor condition at calving and breeding take longer to rebreed. Body condition score on the 1 to 9 scale is a basic tool for judging where your cows stand. A nutritionist or extension specialist can help you set a feeding plan to reach target condition for your herd and region.

Fertility records mean little if nutrition problems are masking the cow's true ability. Fix feed first, then judge the cow.

Young cows nursing their first calf are the hardest to rebreed because they are still growing. Plan feed for them separately from mature cows, and expect them to need extra attention.

Herd health and reproductive disease

Reproductive diseases can cause open cows, abortions and weak calves. Some are reportable or regulated, and some affect people. If cows abort or you see unexplained breeding failure, call your veterinarian promptly and follow their handling advice. Do not handle aborted tissue without guidance, and contact the state veterinarian or USDA APHIS as your vet directs.

A vaccination and biosecurity plan written with your vet protects fertility. Keep records of all treatments and follow withdrawal times exactly.

Common mistakes and what to ask

Mistakes include keeping open cows for sentimental reasons, skipping pregnancy checks, using bulls without a soundness exam and judging fertility in a poor feed year.

Ask your vet: When should we check bulls and cows? What do our open rates suggest about herd health? Ask your extension office to help evaluate your breeding season length and nutrition program.

Culling open cows is hard when prices are high, but keeping them quietly lowers the average fertility of the whole herd.

When to get help: Call your veterinarian for breeding soundness exams, pregnancy checks and any abortions or unexplained open cows. Ask an extension specialist or nutritionist about body condition goals and a feeding plan for your herd.

Sources and further reading

Organization homepages are linked so you can search them for current guidance on this topic.

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