Herd profitability depends on regular calving, and regular calving depends on inseminating at the right time. Missing heat or inseminating at the wrong time can both prevent conception and extend the number of open days. Here are the basics.
1. What is heat (estrus), and how long does it last?
Cows come into heat about every 21 days on average (18–24 days). Heat lasts approximately 12–18 hours, so observing the herd at least 2–3 times a day is important for noticing the signs. Observation is most effective in the morning and evening, when the animals are calm.
2. Signs of heat
The most reliable sign is when a cow stands still and allows other animals to mount her (standing heat). Other signs include restlessness and frequent bellowing, mounting other cows, swelling of the vulva and clear discharge, a temporary drop in appetite and milk yield, and rubbed hair at the base of the tail.
3. The best insemination time: the AM–PM rule
The highest chance of conception is achieved when insemination takes place about 12 hours after the onset of heat. The practical rule is: if you notice heat in the morning, inseminate that evening; if you notice it in the evening, inseminate the next morning. Inseminating too early or too late lowers the conception rate.
4. When should a cow be inseminated after calving?
After calving, time is allowed for the uterus to recover. This "voluntary waiting period" is generally 45–60 days. Inseminating earlier can reduce the chance of conception, while waiting too long extends the calving interval and open days, resulting in lost productivity.
These are general ranges; the appropriate timing varies with the cow's condition, body condition score and health. Veterinary guidance is recommended for a program tailored to your herd.
5. Gestation length and pregnancy checks
Gestation in cows lasts an average of 280–285 days. If the animal does not return to heat after insemination, pregnancy is possible; however, confirm it with a pregnancy check (veterinary examination/ultrasound) about 30–45 days after insemination. If she did not conceive, the cow will usually return to heat about 21 days later, so observe her again on days 18–24 after insemination.
6. Monitoring is difficult without records
It is impossible to remember which cow showed heat and when, when she was inseminated, when her pregnancy check is due, and when calving is expected. Recording every heat and insemination event and following them with automatic reminders is one of the easiest ways to improve conception rates.
Track insemination and pregnancy with Alprivo
Enter the insemination date in Alprivo Herd Management, and pregnancy checks, drying-off and expected calving will be added to the agenda automatically so you do not miss a step.