In this study, sows were mated at first estrus after weaning, delayed mating after weaning was not practiced, and AI followed by natural mating were used. Pregnancy was confirmed on d 21 by ultrasonography. Females, including both gilts and sows, were housed in stalls on a partially slatted floor from first mating throughout gestation. Horizontal bars separated the individual stalls sides, but no horizontal bars were in the front of the females. The dimensions of the gestation crates were 213 cm long, 57 cm wide, and 106 cm high. Pregnant females were daily fed 2 kg of a gestation diet of corn and soybean meal in the morning. The calculated composition of the gestation diet was 13.2% CP, 0.9% Ca, 0.8% P, and 3,180 kcal/kg of ME (as-fed basis).