1. Department of Nutrition, Exercise and Sports, Faculty of Science, University of Copenhagen, Frederiksberg C, Denmark;
2. Department of Reproduction, Faculty of Health and Medical Sciences, University of Copenhagen, Frederiksberg C, Denmark;
3. National Veterinary Institute, Technical University of Denmark, Frederiksberg C, Denmark; and
4. Department of Animal Science, Immunology and Microbiology, Aarhus University, Tjele, Denmark