The effect of age at first mating on lifetime reproductive performance of sows has been examined by Brooks and Smith (1980). They concluded that early mating had no adverse effects on later fertility and resulted in greater overall efficiency of feed utilisation. This may not be true in modern intensive production systems where early weaning results in depressed litter size (Clark and Leman, 1986).

Gilts were reared in groups of eight under an ad libitum feeding system and isolated from male pigs from 30 kg live weight until boar exposure at 200, 220 or 240 days of age (= B200, B220 and B240). Groups were transferred intact to the breeding area at the appropriate age. A mature boar was penned in the house, allowed in the pen with the gilts for 1-2 hours daily for the first 3 days and later only under supervision to allow heat detection. Animals were mated at the first observed oestrus after boar exposure. Those not mated by 35 days after boar exposure were culled.