Dairy farming is a continuous process of cows calving down (giving birth), producing milk and getting pregnant again. To maintain a high standard of reproduction management, the next expected calving down date should be less than 13 months from the present calving date.
When the calving interval (time between calving down dates) is too long, it reduces the milk yield of the herd while also slowing down the herd's genetic progress. Higher milk production and more calves born per year are just two of the economic benefits of good reproduction management.
To get cows pregnant, natural service (a bull), can be used. However, for small herds keeping a bull is expensive and often causes management problems. They can get aggressive, and need to be kept separate and also need to be fed. In addition, by using the same bull every time, genetic progress is limited. In the ‘old’ days, bulls were shared amongst farmers, but this can cause fertility diseases to spread and all cows then become infertile. Because of this, the artificial insemination (AI) of cows was developed.
Artificial insemination is generally cheaper than using a bull. It is a simple technique that involves the deposition of live semen at the correct time and place inside the genital tract of dairy cows for conception. Artificial insemination of cows is a standard practice in commercial dairy herds. Genetic progress is higher when using AI. This is because semen from a world-wide range of bulls is available at a lower cost than keeping a bull. However, in AI, the fertility of dairy cows depends on the ability of people to recognize when cows are in heat.
In addition, they need to know how to deposit semen at the right time and place for conception to take place. AI is taught on short, 2-day, courses or can be learnt from a veterinarian. Some companies supplying bull semen, offer AI as an extra service, and some veterinarians can also perform AI.