1. Reproduction and Obstetrics Department of Animal Medicine and Surgery; University of León; León Spain
2. Laboratory of Equine Reproduction and Equine Spermatology; Veterinary Teaching Hospital; University of Extremadura; Cáceres Spain
3. Department of Molecular Biology; University of León; León Spain
4. Portalagre Polytechnic Institute; Superior Agriculture School of Elvas; Elvas Portugal
5. Division of Reproduction; Faculty of Veterinary Medicine and Animal Sciences; Swedish University of Agricultural Sciences; Uppsala Sweden
6. Department of Clinical and Experimental Medicine; Faculty of Medicine & Health Sciences; Linköping University; Linköping Sweden