Successful breeding herds require accurate heat detection, which is easy to learn. However, it is the ovulation time that varies and is difficult to predict. Good heat detection will help determine the optimal timing of insemination. Picking older boars and using them at least once a week is optimal for pheromones and for keeping the boar interested. It is important that boars be exposed to sows at a specific time because the sows standing reflex is so short. Nose to nose contact should be ensured and the boars should be actively rubbing or grunting to the sows. No more than 4 to 8 sows should be checked at a time. The ventilation should not be too fast, or the boar odour will be washed away. This is more a problem in the summer heat, and a solution could be the use of a “stink stick” (rag soaked in boar urine, semen, gel plug) to wave in front of the sows. Pre-estrus detection is also important to predict when standing heat will occur. Signs of pre-estrus include increased vocalization, increased activity, bar biting, climbing the crate, riding others, and/or a swelling/red vulva. It is important to note in gilts that the swollen vulva will actually reduce once estrus begins. Signs of estrus may include going off feed, restlessness, high-pitched grunt, rub marks on her back, pricked ears, and more. A sticky, tacky feel to vulva mucus is an indication of estrus as well. The generally agreed optimal insemination time is between 4 and 24 hours prior to ovulation. Using between 1 and 3 inseminations is effective, but inseminating too late in estrus can be detrimental. The life of the egg in the female is thought to be 8 hours, and insemination 4 hours beforehand is thought to be best. Inseminating too late can increase the chance of abnormal fertilization and may interfere with proper uterus preparation. Knowledge of weaning to estrus interval, duration of estrus, and estrus to ovulation intervals can help producers to set up an insemination schedule following certain characteristics of the sows heat (with special attention being given to gilts). Sows that return to heat early after weaning should be delayed and sows that return late should be bred immediately after detection.