The present invention relates to the use of 25-hydroxy-vitamin D3 to improve the general health status of female animals at least during gestation and/or lactation. The invention also relates to the use of 25-hydroxy-vitamin D3 in animal breeding. More particular, the invention relates to the use of 25-hydroxy-vitamin D3 for improving litter size and vitality of piglets in pig breeding and for providing better body frame and increasing gestation backfat gain, reducing lactation backfat loss and increasing lactation feed intake of sows and gilts.