Infertility and Subfertility in Cows

Infertility in cows means a cow cannot establish or maintain a pregnancy. Subfertility is more common and means reproduction is happening less efficiently than expected. A cow may take too long to return to estrus after calving, need several services to conceive, lose an embryo early, or become pregnant late in the breeding season.

In real herds, this often shows up as a repeat breeder cow, a longer calving interval, more open days, or too many cows still not pregnant after the planned breeding window. Some cows look healthy and cycle normally, so the problem may be missed until pregnancy checks or herd records show a pattern.

This is not always a single-cow problem. Fertility can be affected by the uterus, ovaries, nutrition, calving recovery, semen quality, bull fertility, breeding timing, housing stress, or infectious disease. That is why your vet usually looks at both the individual cow and the herd system before recommending next steps.

Many cases are multifactorial. One cow may have delayed cycling because she calved thin, lost more condition after freshening, and then developed uterine inflammation. Another may be bred at the wrong time because heat detection is inconsistent. In beef herds using natural service, a subfertile bull can affect many cows at once.

Important causes include poor nutrition and body condition, especially low energy status around calving; postpartum disease such as metritis, endometritis, retained fetal membranes, dystocia, ketosis, or other transition disorders; and ovarian problems such as cystic ovarian disease or failure to ovulate. Merck notes that healthy females need adequate age, weight, and nutrition status for successful estrus control and breeding, and that thin cows or cows losing weight after calving may have delayed return to estrus.

Breeding management also matters. Missed heats, poor insemination timing, semen handling errors, low semen quality, and inadequate bull breeding soundness can all reduce conception. Merck recommends annual breeding soundness exams for bulls, including physical exam, scrotal circumference, and semen evaluation, ideally about 1 month before the breeding season.

Infectious causes are especially important in herd outbreaks or natural-service systems. Trichomoniasis and bovine genital campylobacteriosis can cause early embryonic loss, irregular cycles, repeat breeding, and lower pregnancy rates. Your vet may also consider other reproductive or abortion-related infections based on region, herd history, vaccination status, and biosecurity.

Diagnosis starts with a careful history. Your vet will usually ask about calving date, postpartum problems, breeding dates, observed heats, semen source, synchronization use, pregnancy check results, nutrition, body condition, and whether the herd uses AI, natural service, or both. In many cases, the records tell part of the story before the reproductive exam even begins.

The physical and reproductive workup may include body condition scoring, transrectal palpation, and ultrasonography to assess the uterus and ovaries. Pregnancy diagnosis in cattle is commonly done by transrectal palpation, while ultrasound is increasingly used to evaluate pregnancy status and ovarian structures. If uterine disease is suspected, your vet may perform a vaginal exam, vaginoscopy, discharge scoring, or collect a uterine sample for cytology. Merck describes clinical endometritis in cows as purulent or mucopurulent discharge after 21 days postpartum without systemic illness, while subclinical endometritis requires uterine cytology for diagnosis.

If the problem appears herd-wide, your vet may expand the workup. That can include reviewing heat detection and insemination timing, checking synchronization compliance, evaluating transition-cow health, and testing bulls. A bull breeding soundness exam is often essential in natural-service herds because one infertile or subfertile bull can lower pregnancy rates across the group.

In some cases, diagnosis is partly a process of elimination. Your vet may rule out pregnancy, uterine infection, ovarian cysts, poor body condition, and bull or semen problems before deciding the most likely cause of repeat breeding or delayed conception.

Prevention starts before breeding season. Cows need to calve in appropriate body condition, recover well after calving, and receive nutrition that supports return to estrus. Merck emphasizes that nutrition is one of the most important management factors in cattle reproduction, and that cow condition at calving strongly affects rebreeding. Thin cows, cows losing weight, and cows with transition disease are more likely to have delayed fertility.

Good transition-cow management is one of the most practical prevention tools. Work with your vet to reduce dystocia, retained fetal membranes, metritis, ketosis, and other fresh-cow disorders. These problems do not always end when the cow looks better. They can continue to affect conception weeks later.

Breeding management matters too. Improve heat detection, keep accurate records, confirm pregnancy on schedule, and identify open cows early enough to rebreed or make culling decisions. In natural-service herds, bulls should have regular breeding soundness exams before the season. In AI programs, semen storage, thawing, and insemination timing should be reviewed whenever conception rates slip.

Finally, protect the herd with biosecurity. Test and manage incoming animals appropriately, avoid sharing untested bulls, and ask your vet about region-specific reproductive disease risks and vaccination plans. Preventing one infectious reproductive problem can protect the fertility of many cows at once.