(190) AI is now used extensively in many countries where it is either purchased from a commercial centre or produced on the farm. It is common practice to carry out one service, usually the first, with the boar followed up 24 hours later by AI. For herds with 300 sows or more it is cost effective to collect semen from boars on the farm daily and inseminate within one hour of collection (twice 24 hours apart). The procedures and equipment necessary are simple and described in chapter 15 Semen collection. Many herds today use only AI and produce excellent results particularly with the advent of the collapsible semen pack.