HOURLY FLUCTUATIONS IN THE BLOOD-LEVELS OF MELATONIN, PROLACTIN, LUTEINIZING-HORMONE, FOLLICLE-STIMULATING-HORMONE, TESTOSTERONE, TRI-IODOTHYRONINE, THYROXINE AND CORTISOL IN RAMS UNDER ARTIFICIAL PHOTOPERIODS, AND THE EFFECTS OF CRANIAL SYMPATHECTOMY Artigo Académico