The profitability of a herd depends on regular calving, and regular calving runs through inseminating at the right time. Missing a heat, or inseminating at the wrong moment, both stops pregnancies from holding and lengthens the days spent empty. Here is the basic logic.
Below we set out how to catch heat on the farm, how to choose the hour to inseminate, the mistakes most often made, and when you should call a veterinarian. There is a short checklist at the end of the article.
1. What is heat (oestrus), and how long does it last?
Cows come into heat on average every 21 days (18–24 days). A heat lasts about 12–18 hours, which means observing at least 2–3 times a day matters if you are to notice the signs. Observation morning and evening, while the animals are calm, is the most productive.
Ovulation happens after the signs of heat have ended. It is generally accepted that ovulation occurs about 10–14 hours after the end of the standing heat period. The egg stays fertilisable only briefly; sperm, too, need a few hours in the female tract to become capable of fertilising. That is why insemination is done not right at the start of heat but a little after it: the sperm need to go on ahead so that the egg finds them ready.
These times are averages. In high-yielding cows heat is shorter and the signs are faint; in heifers it usually passes more obviously. Heat also shortens and the signs weaken in the hot summer months; that is one of the reasons conception rates fall in summer in many parts of Turkiye.
2. The signs of heat
The surest sign is the cow allowing other animals that mount her without moving away (standing to be mounted). Other signs: restlessness and frequent bellowing, mounting other cows, swelling and clear discharge from the vulva, a temporary drop in appetite and milk yield, and rubbed hair at the tail head.
Separating the signs into "conclusive" and "supporting" makes your job easier on the farm:
| Sign | What it means | What to do |
|---|---|---|
| Standing to be mounted (not moving away from the animal that mounts her) | Conclusive heat | Note the hour and inseminate by the morning-evening rule |
| Rubbing, mud or soiled hair at the tail head | Close to conclusive; it means she has been mounted | Put the animal under close watch and observe her again the same day |
| Clear, stringy discharge; swelling and redness | Supporting | Not enough on its own; look for the standing sign |
| Mounting others, restlessness, bellowing | Supporting (it can also come before heat) | Observe more often over the next 12 hours |
| Coming off feed, a temporary drop in milk yield | Supporting | Judge it together with the other signs |
Inseminating on the strength of discharge or restlessness alone is the most common error of timing. Supporting signs can be seen both before and after heat; what gives you the hour is the standing behaviour.
3. How is heat observation done on the farm?
- Look at least 2, and if you can 3, times a day. Observation of 20–30 minutes before the morning milking, after the evening milking and late at night is recommended. Most heat behaviour is seen at night and towards morning; a farmer who only looks during the day misses a large share of heats.
- Do not observe while feeding or in the rush of milking. Mounting behaviour is not seen while the animals are locked at the trough. Look while the herd is calm and moving freely.
- Mind the floor. On slippery concrete cows avoid mounting; the heat is there but you cannot see it. An exercise area, a bedded pen or a raked earth floor makes heat visible.
- Make sure you can read the tag from a distance. When the number cannot be read, heats often get written against the wrong animal; use an extra marker with large numbers if you need to.
- Use a helping marker. A chalk or paint stripe applied at the tail head is rubbed off when she is mounted; it shows you in the morning a heat that happened at night.
- Write it down with the hour the moment you see it. Something like "06:30 in the morning — number 142 stood to be mounted". Without the hour you cannot apply the morning-evening rule.
Do not leave observation to one person; whoever is milking, feeding or spreading bedding should write what they see in the same book. Keeping the herd records in order matters no less than the observation itself at this point.
4. The best time to inseminate: the morning-evening rule
The highest chance of pregnancy is obtained by inseminating about 12 hours after the start of heat. The practical rule is this: if you noticed the heat in the morning, inseminate the same day in the evening; if you noticed it in the evening, inseminate the next morning. Inseminating far too early or far too late lowers the conception rate.
| When you first saw the heat | Time to inseminate |
|---|---|
| Early morning (during milking) | Late afternoon the same day |
| Afternoon / evening | The next morning |
| The tail paint found rubbed off in the morning (the heat may have started at night) | That afternoon; if the starting hour is unknown, try to see the standing behaviour again |
There is only one condition for the rule to work: knowing the hour at which you first saw the heat. You cannot hit the right hour on the strength of "she was in heat at some point yesterday". Take the inseminator's schedule into account as well; picking up the phone the moment you see the heat stops the hour from slipping.
If you are not sure about the heat, do not have her inseminated. Inseminating a pregnant cow by mistake can cause abortion. For animals you are in doubt about, first look up the last insemination and pregnancy check in the records.
5. What to watch on the day of insemination
- Do not put the animal under stress. Long chases, fights, transport and extreme heat all lower the success of insemination. On hot days move the job to the cool part of the day.
- Let an authorised person do the insemination. In cattle, artificial insemination is carried out under the legislation by people holding a certificate of authority. Storing, transporting and thawing the straw is technical work and is the responsibility of whoever carries it out.
- Cleanliness. The place where the insemination is done and the animal's hindquarters must be clean; a procedure carried out in a dirty environment raises the risk of uterine infection.
- Leave the animal in peace afterwards. Do not plan transport, hoof trimming and similar jobs for the same day.
- Write the record down at once. Date, hour, which bull's straw, and who carried out the insemination. Without these four pieces of information, neither a pregnancy check can be planned later nor the source of a problem found.
6. When is a cow inseminated after calving?
After calving, a period is allowed for the uterus to recover. This "voluntary waiting period" is generally 45–60 days. Inseminating earlier lowers the chance of a pregnancy holding; leaving it too late lengthens the interval between calvings and the days spent empty, and so causes a loss of yield.
These periods are general values; they change with the cow's situation, her condition and her health. Veterinary support is recommended for a programme suited to your herd.
In most cows the first heat after calving is seen before the waiting period is over. Even if you do not inseminate at that first heat, be sure to record it: it shows that the animal's cycle has started, and you then know roughly when the next heat will come. Cows that have shown no heat at all more than 60 days after calving are the first on the list to be examined.
In the period after calving, the animal's body condition and her feeding directly affect whether she holds. Cows that have lost too much condition, or that are too fat, come into heat late and conceive late. So do not think of the breeding calendar separately from the feeding and ration plan.
7. First insemination in heifers
In heifers what decides is development, not age. Inseminating a heifer early, before she has reached an adequate body weight, leads to a difficult calving and low yield in the first lactation; leaving it too late lengthens the time she is kept without giving milk. Follow your heifers by measurement, and get your veterinarian's opinion on the target weight.
8. Length of pregnancy and the check
In cows, gestation lasts on average 280–285 days. If the animal does not come into heat again after insemination, pregnancy is likely; even so, confirm it with a pregnancy check (veterinary examination or ultrasound) about 30–45 days after insemination. If the pregnancy did not hold, the cow shows heat again after about 21 days, so observe again on days 18–24 after insemination.
Do not leave the pregnancy check to the assumption that "she did not come into heat, so she must be pregnant". There are cows that show heat without it being noticed, and cows that do not come into heat although they are not pregnant; both end in the same result, months gone to waste. In cows whose pregnancy is confirmed, the rest of the calendar runs like this:
- 18–24 days after insemination: observation for a return to heat.
- 30–45 days after insemination: the pregnancy check.
- About 2 months before the expected calving: drying off.
- The period close to calving: preparing the calving pen and for the calf.
9. Common mistakes and how to spot them
- Looking for heat only during the day. The sign: if the interval between two heats in the herd often comes out near twice 21 days (about 36–48 days), a heat in between has been missed.
- Not writing down the hour. The sign: inseminations are always done at the same hour (when the inseminator arrives), with no relation to the start of heat. The conception rate falls.
- Deciding on a single sign. The sign: if some of the animals inseminated come into heat again 3–10 days later, animals may be being inseminated at the wrong time or while not in heat at all.
- Having the wrong animal inseminated. The sign: a cow shown as pregnant in the records coming into heat, or a cow recorded as never inseminated turning out to be pregnant. Tag readability and record discipline should be questioned.
- Saying "let this month go by" and waiting. The sign: empty days and the calving interval lengthen quietly; every cycle that gets away is a loss of about three weeks.
- Observing on a slippery floor. The sign: almost no mounting is seen in the barn, yet the cows regularly give "quiet" signs every 21 days.
- Not allowing for heat stress. The sign: the conception rate of animals inseminated in the summer months is markedly low. Shade and cooling are part of breeding management.
- Skipping the pregnancy check. The sign: cows found not to be pregnant while a calving was being awaited. Those months do not come back.
10. Which signs call for a veterinarian?
The situations below are not ones to say "let us wait a little longer" about; consult your veterinarian before they turn into a loss at herd level:
- A cow showing no heat at all more than 60 days after calving.
- A cow inseminated repeatedly that does not conceive (particularly after the third insemination).
- An animal coming into heat at irregular intervals (for example every 7–12 days, or constantly beyond 30 days).
- A cow showing constant heat behaviour and never settling.
- Purulent, foul-smelling or bloody discharge from the reproductive tract.
- The afterbirth not being dropped after calving, loss of appetite, fever, a sudden drop in milk yield.
- An abortion — even a single case must be reported and investigated.
- The post-calving check of cows that had a difficult calving or needed assistance at calving.
- More than one cow in the herd failing to hold in the same period.
For animals that show no heat or fail to hold, there are examination and synchronisation approaches that veterinarians use. These are applied on and under a vet's decision and supervision; no medicine, dose or treatment protocol appears in this article.
11. Records and official procedures
In Turkiye, tagging cattle and entering them in the registration system is compulsory; artificial insemination is likewise carried out by certified people, and both the insemination performed and the calf born must be recorded. Herd book and preliminary herd book registration and calf support applications also rest on these records. Because the rules are updated from period to period, contact your provincial or district directorate of agriculture and forestry and your veterinarian for the exact programme and current conditions. Your own record book does not take the place of the official record; but it is the source that lets you make your notifications on time.
12. Following this without records is hard
Which cow showed heat when, when she was inseminated, when the pregnancy check should be done, when calving is expected — holding these in your head is impossible. Recording every insemination and heat and following them with reminders is one of the most practical ways of improving the conception rate.
Records are not only a reminder but also a measuring tool. You can see your herd's breeding situation in a few simple numbers:
| Measure | What it tells you | How it is worked out |
|---|---|---|
| Days open | How long the animal took to conceive after calving | The days between the calving date and the insemination at which she conceived |
| Calving interval | The herd's breeding tempo; 12–13 months is generally the target | The time between two consecutive calving dates |
| Inseminations per pregnancy | Success at timing and at catching heat | Total inseminations / number of animals that conceived |
| Day of first insemination | Whether the waiting period is being observed | The days from calving to the first insemination |
| Missed cycles | Whether observation is adequate | If the interval between two heats falls on clear multiples of 21 days, observation is being missed |
You can keep these numbers in a hand-written book as well; what matters is keeping them regularly and looking at them from time to time. Ready-made summaries such as the fertility report and calving tracking do the same arithmetic for you.
Heat and insemination checklist
- I observed at least 2, and where possible 3, times a day for 20–30 minutes while the herd was calm.
- I wrote down the hour at which I first saw the heat.
- I checked whether there was a conclusive sign (standing to be mounted).
- If I saw it in the morning I arranged insemination for the evening, and if in the evening, for the morning.
- I observed the 45–60 day waiting period after calving.
- I recorded the insemination date, the hour, the bull and the person who carried it out.
- I made a note to observe for a return to heat on days 18–24.
- I planned the pregnancy check appointment for day 30–45.
- I wrote the drying-off and expected calving dates on the calendar.
- I reported to the veterinarian the animals that showed no heat after 60 days and those inseminated 3 times without holding.
Catching heat is a skill and the timing of insemination is knowledge; what makes both sustainable is cow-by-cow tracking.
Track insemination and pregnancy with Alprivo
Enter the insemination date in Alprivo Herd Management, and let the pregnancy check, drying off and the expected calving date drop into your diary as reminders.