The use of AI results in higher selection intensity, more accurate selection of males based on progeny testing and more accurate estimation of breeding value across herds. The latter is a result of exchange of semen between different nucleus herds, which facilitates the establishment of genetic links between them. AI is used by breeding organizations for most species. For species such as cattle that have low reproductive rates, progeny testing based on AI is a prerequisite for accurate estimation of breeding values for traits of low heritability such as function traits. AI allows faster dissemination of genetic superiority to the commercial population. Sixty to eighty percent of all the AI performed is carried out in cattle. A male identified as superior can leave thousands of progeny in different populations all over the world.