A group of dairy calves

Artificial Insemination (AI) of Dairy Cattle

What is Artificial Insemination (AI)?

Artificial Insemination, or AI, is the process of deliberate fertilisation of a female animal, by a human operator, using previously collected semen. It has been practised in many different species all over the world for over 60 years, from cows and other livestock, to dogs and horses. Some captive breeding programs have even used AI to help increase populations of endangered animals. Millions of people use AI technology on a regular basis and the financial impact of this is huge. Consequently, AI has increased in both popularity and technical advancement since its introduction.1

In the agricultural industry, although the market for AI is increasing in most livestock species, the most common use of AI is in cattle. Both the beef industry and the dairy industry routinely use AI to inseminate their cows as it has a wide range of benefits.

Why does the dairy industry use AI?

The modern dairy industry in many areas of the world is changing. There is a move away from many producers with small herds, to fewer producers with large herds. In the UK, average herd size rose by 97.3% between 1995 and 2018, but the number of producers dropped by 65.8%. Herds in the US are seeing a similar trend, as the median herd size grew from 80 cows in 1987, to 1300 cows in 2017.2 With any herd size, fertility management is a key part of dairy farming, but larger herds give rise to more challenges.

Two bulls fighting
Aggression is common in bulls and can be exacerbated by being around cows in heat.

A clear problem is the need for more bulls to fertilise the cows in a large herd. A top performing mature bull in peak condition would only be able to service 40-50 cows. As a result, breeding large numbers of cows would require more bulls and more management.

Bulls need special facilities to house them safely and skilled handling to ensure everything runs smoothly. Dairy bulls can present a significant danger to anyone who works with them, as they tend to be aggressive.3 This is partly due to their large size and strength, but also their unpredictable behaviour.

Artificial insemination removes the need for producers to have a bull on their farm. Producers can buy semen from many different bulls with different desirable characteristics to then inseminate their cows. Cows with wanted traits, like good milkers or very fertile cows, can be bred with premium semen and so have profitable offspring. For less economically important cows, producers can use cheaper semen and still produce viable calves.

What are the pros and cons of using AI on a dairy farm?


A cow being shown at an agricultural show.
Semen from high quality bulls can be transported around the world with ease.
  • A producer can chose which semen to use with each cow. As such, selecting for specific traits is much easier and quicker than traditional breeding.
  • No additional infrastructure and feeding costs associated with keeping a bull or bulls.
  • No additional danger to farm workers from handling bulls.
  • Sexed semen can be used to produce calves of specific sexes. This then helps to decrease the number of unwanted male calves.
  • Bigger herds can be managed more easily and there are many AI programs which help producers set up their own systems.
  • Semen from particularly high quality bulls can be frozen and used across the world for many years.
  • One collection of semen can be used to inseminate many cows, improving efficiency.
  • Movement of bulls can transmit disease between farms, AI reduces this risk.
  • Herd synchronisation and AI go hand-in-hand, so making management easier.
  • Technologies are available which extend the life of the sperm inside the cow, therefore providing more flexibility around timing of insemination. This can greatly increase conception rate.


  • Accurate heat detection is necessary to know when to AI a cow.
  • AI requires specialised equipment and trained technicians to perform.
  • Semen straws can be costly depending on the bull.
  • Managing bulls and semen collection require specialised facilities and trained personnel.
  • AI straws need to be kept frozen until use and then must be carefully temperature controlled.

In conclusion, there are great benefits to using artificial insemination in the dairy industry, and many producers use it as the sole means of breeding. There are also those who use a mixture of AI and bulls to service their herds. There is no one strategy which works for every herd in every location, so it is important to consider all the factors around AI when deciding what method is best for a particular herd.


  1. Vishwanath, R. Artificial insemination: the state of the art. Theriogenology 59, 571–584 (2003).
  2. MacDonald, J. M., Law, J. & Mosheim, R. Consolidation in U.S. Dairy Farming. 61.
  3. Sheldon, K. J., PhD, G. D., EdD, W. E. F. & PhD, J. L. A. Bull-Related Incidents: Their Prevalence and Nature. J. Agromedicine 14, 357–369 (2009).