title: Exogenous melatonin does not improve the freezability of Blanca Andaluza goat semen over exposure to two months of short days.
abstract: This paper compares the effects of exposure to exogenous melatonin (MEL), short days (SD, 8h of light) and long days (LD, 16 h of light), on reproductive activity, sperm motility and other reproductive variables, in Blanca Andaluza bucks. Fourteen males were spilt into two groups of seven animals (G1 and G2). They were subjected to five alternations of 2 months of LD followed by 2 months of SD or MEL before the experimental period of three consecutive intervals of: (1) 2 months of SD (G1, N=7) or MEL (G2, N=7); (2) 2 months of LD (G1+G2, N=14); and (3) 2 months of SD (G2, N=7) or MEL (G1, N=7). Plasma testosterone concentration, live weight, testicular weight and fresh semen quality were determined weekly. Semen was also cooled and frozen-thawed every fortnight, and the same quality variables measured as for fresh sperm. When the bucks were under LD treatment, the testosterone concentration was lower than when under MEL or SD treatment (P<0.01); values for the semen concentration and total number of sperm per ejaculate were also higher (P<0.001). No differences were observed between the MEL and SD treatments in terms of fresh, cooled or frozen-thawed sperm quality. Only some quality variables on fresh semen were improved by MEL and SD treatment (P<0.05). In conclusion the results of the present experiment showed that MEL improved the fresh semen motility variables, but this did not improve the motility of frozen-thawed sperm over that recorded for either SD or LD treatment.
authors.affiliation: Departamento de Ciencias Agroforestales, Universidad de Huelva, "Campus de Excelencia Internacional Agroalimentario, ceiA3", Carretera Huelva-Palos de la Frontera s/n, 21819 Palos de la Frontera, Huelva, Spain.
authors.forename: L
authors.initials: L
authors.lastname: Gallego-Calvo
authors.affiliation: Universidad Arturo Prat, Facultad de Recursos Naturales Renovables, Avenida Arturo Prat, 2120 Iquique, Chile.
authors.forename: M C
authors.initials: MC
authors.lastname: Gatica
authors.affiliation: Departamento de Reproducción Animal, SGIT-INIA, Madrid, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Santiago-Moreno
authors.affiliation: Departamento de Ciencias Agroforestales, Universidad de Huelva, "Campus de Excelencia Internacional Agroalimentario, ceiA3", Carretera Huelva-Palos de la Frontera s/n, 21819 Palos de la Frontera, Huelva, Spain.
authors.forename: J L
authors.initials: JL
authors.lastname: Guzmán
authors.affiliation: Departamento de Ciencias Agroforestales, Universidad de Huelva, "Campus de Excelencia Internacional Agroalimentario, ceiA3", Carretera Huelva-Palos de la Frontera s/n, 21819 Palos de la Frontera, Huelva, Spain. Electronic address: zarazaga@uhu.es.
authors.forename: L A
authors.initials: LA
authors.lastname: Zarazaga
mesh_terms: D000818:Animals; D005615:Freezing; D006041:Goats / Q000502:physiology*; D008297:Male; D008550:Melatonin / Q000494:pharmacology*; D009929:Organ Size / Q000528:radiation effects; D017440:Photoperiod; D012661:Semen / Q000187:drug effects* / Q000502:physiology; D012662:Semen Preservation / Q000379:methods / Q000662:veterinary*; D012726:Sexual Behavior, Animal; D013081:Sperm Motility; D013737:Testis / Q000033:anatomy & histology / Q000528:radiation effects; D013739:Testosterone / Q000097:blood; D013997:Time Factors
chemical_list: D013739:Testosterone; D008550:Melatonin
keywords: Bucks; Melatonin; Photoperiod; Semen cryopreservation