Acta Veterinaria Scandinavica 2009, 51:48 http://www.actavetscand.com/content/51/1/48 31. O'Callaghan D, Boland MP: Nutritional effects on ovulation, embryo development and establishment of pregnancy in ruminants. Anim Sci 1999, 68:299-314. 32. Short RE, Bellows RA, Staigmiller RB, Berardinelli JG, Custer EE: Physiological mechanisms controlling anoestrus and infertil- ity in postpartum beef cattle. J Anim Sci 1990, 68:799-816. Publish with Bio Med Central and every scientist can read your work free of charge "BioMed Central will be the most significant development for disseminating the results of biomedical research in our lifetime." Sir Paul Nurse, Cancer Research UK Your research papers will be: available free of charge to the entire biomedical community peer reviewed and published immediately upon acceptance cited in PubMed and archived on PubMed Central yours — you keep the copyright Submit your manuscript here: http://www.biomedcentral.com/info/publishing_adv.asp BioMedcentral Page 6 of 6 (page number not for citation purposes)