Rearing dairy heifers

Abstract

On dairy farms, rearing heifers is aimed at having efficient milking cows, from reproductive, productive and longevity points of views. The animals also need to be adapted to their living environment and to be reared at the lowest cost possible. Practical solutions exist and the present paper is an update of rearing dairy heifer procedures, from birth to first calving, and their subsequent performances. Age at first calving (24, 30 or 36 months of age in seasonal calving systems for example) is of importance when considering the dairy system. With first calving at 24 months of age, puberty should arise early and body development and reserve should be adequate. However, a too high growth rate should be avoided because of possible excessive fatness that could have a deleterious effect on long-term performances. With calving at 30 or 36 months of age, growth intensity could be reduced, particularly when animals are housed during the winter. But insufficient growth performances (400 g/d or less) could be deleterious for reproduction and longevity. The grazing system, optimising compensatory growth capacity of heifers, can reduce rearing costs significantly. When seasonal calving procedures are used in the herd, hormonal treatment could be useful. Reducing even more the age at first calving (20 months or less), resulting in low rearing and labour costs… is probably of interest but has to be studied in detail.