Effect of Raising Dairy Heifers on Their Performance and Reproduction after 12 Months

The objective of this study was to test the hypotheses that a heifer’s growth, health, and reproduction after 12 months are impacted by rearing (feeding/housing) before weaning, their season of birth, and the father’s lineage. Fifty-one Holstein heifers, born during January–March (SB1), April–June (SB2), July–September (SB3), and October–December (SB4) and originating from four fathers, were assigned to one of the three rearing treatments: restricted suckling (RS), calf in a pen with the mother until the 21st day, sucking three times daily, then group pen (6 kg milk) to weaning; unrestricted suckling (US), calf in a pen with foster cows (6 kg milk) to weaning; and conventional rearing (CR), calf in a hutch until the 56th day, then group pen to weaning (milk replacer 6 kg). After weaning on the 84th day, heifers were kept in groups with the same ration. The growth of the live body weight (LBW), health, and reproduction were recorded. The LBW had a tendency to increase from the 360th to the 570th days in the US, and the reduced growth of the LBW was shown in the CR. Heifers of SB2 had the highest LBW at 570 days of age. The ages of the first insemination service and the conception varied significantly among the rearing groups. The results indicate that a heifer rearing method may have a significant impact on their later growth and fertility.