Artificial insemination basics

Artificial insemination (AI) is the cheapest way to put elite genetics into a herd: a straw of semen costs far less than the bull. It does, however, reward good management and punish shortcuts. This is an overview; your veterinarian or an AI technician should design the program for your herd.

Heat detection

A cow is only receptive for a short time. Standing heat usually lasts about 12 to 24 hours, and some cows show it only a few times.

• The sure sign is a cow that stands still to be mounted by another animal.
• Secondary signs include restlessness, mounting others, a clear mucus discharge and a swollen vulva.
• Watch for at least 30 minutes at least twice a day — early morning and late afternoon are best. Heat-detection aids (tail paint, patches, activity monitors) help a lot.

Timing. Cows ovulate after the end of standing heat, so the long-standing guideline is the AM–PM rule: a cow first seen standing in the morning is inseminated that evening; a cow first seen in the evening is inseminated the next morning — roughly 12 hours after first standing.

Synchronization and timed AI

Synchronization programs use a sequence of reproductive hormones to bring a group of females into heat — or to ovulation — at a predictable time. Fixed-time AI protocols let you inseminate a whole group on one day without heat detection. Protocols differ for cows and heifers and are updated as research improves them; your veterinarian chooses the protocol and the products. Synchronization works best in females that are cycling, in good body condition, and well past calving.

Handling frozen semen

Frozen semen is easily damaged by careless handling, and damage cannot be seen.

• Keep the liquid nitrogen in the tank topped up and check it on a schedule.
• When removing a straw, keep the canister below the frost line in the neck of the tank and work quickly.
• Thaw in a water bath at about 35 °C (95 °F) for about 45 seconds unless the semen supplier specifies otherwise.
• Only thaw as many straws as can be used within about 15 minutes, keep them warm and away from sunlight and cold, and never refreeze.
• Keep records: straw identification, cow, date, time and technician.

When to use a professional

A trained AI technician places semen correctly and quickly, and with expensive or limited semen this is often worth the fee. Many breeders also take an AI course themselves. A veterinarian should be involved in the herd's reproductive program, especially synchronization and pregnancy diagnosis.

What success looks like

Conception rates depend heavily on nutrition and body condition, how long since calving, semen quality and handling, timing and technician skill. Sexed semen generally achieves lower pregnancy rates than conventional semen — under good conditions about 70 to 90 percent of conventional — so it is usually used on the most fertile females with excellent heat detection.

Key takeaways

• Standing to be mounted is the true sign of heat; inseminate about 12 hours later (AM–PM rule).
• Synchronization lets you inseminate groups at a fixed time; let your vet pick the protocol.
• Thaw at about 35 °C / 95 °F for 45 seconds and use within 15 minutes.
• Good nutrition and body condition matter as much as the semen.