title: Melatonin administration enhances the reproductive capacity of young rams under a southern Mediterranean environment.
abstract: This study tested the effect of melatonin treatment, initiated in late February on reproductive traits of young rams. A total of 14 young Barbarine rams were used. Seven animals were treated with three melatonin subcutaneous implants (Melatonin) on 28 February while the remaining rams remained untreated (Control). After 60 days of melatonin administration, scrotal circumference reached average values of 32.1 ± 1.54 and 29.5 ± 1.0 cm for Melatonin and Control animals, respectively (P < 0.05). Semen characteristics did not differ between groups; melatonin treatment tended (P = 0.091) to increase sperm concentration 60 days after implantation when means reached 5.87 ± 0.703 and 4.61 ± 0.654 × 10(9) spermatozoa/mL for Melatonin and Control rams, respectively. Melatonin treatment significantly affected total activity time, number of lateral approaches and mount attempts in comparison to controls. During a 6-h sampling period, mean plasma testosterone concentrations increased as a result of melatonin treatment (P < 0.001) and testosterone pulse frequency averaged 3.45 ± 2.24 and 1.25 ± 1.0 (P = 0.086) for Melatonin and Control rams. Data clearly suggest that abrupt treatment of young rams with melatonin implants in winter is sufficient to improve reproductive traits.
authors.affiliation: International Centre for Agricultural Research in the Dry Areas (ICARDA), Amman, Jordan.
authors.forename: Mourad
authors.initials: M
authors.lastname: Rekik
authors.affiliation: Ecole Nationale de Médecine Vétérinaire, Sidi Thabet, Tunisia.
authors.forename: Rahma
authors.initials: R
authors.lastname: Taboubi
authors.affiliation: Ecole Nationale de Médecine Vétérinaire, Sidi Thabet, Tunisia.
authors.forename: Imene
authors.initials: I
authors.lastname: Ben Salem
authors.affiliation: CEVA Santé Animale, Tunis, Tunisia.
authors.forename: Younes
authors.initials: Y
authors.lastname: Fehri
authors.affiliation: Institut Supérieur Agronomique de Chott Meriem, Sousse, Tunisia.
authors.forename: Cyrine
authors.initials: C
authors.lastname: Sakly
authors.affiliation: Laboratoire de Recherche Productions Animales et Fourragères, Institut National de la Recherche Agronomique de Tunisie (INRAT), Ariana, Tunisia.
authors.forename: Narjess
authors.initials: N
authors.lastname: Lassoued
authors.affiliation: International Centre for Agricultural Research in the Dry Areas (ICARDA), Amman, Jordan.
authors.forename: Muhi Eddine
authors.initials: ME
authors.lastname: Hilali
mesh_terms: D000375:Aging; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D005298:Fertility / Q000187:drug effects; D007989:Libido / Q000187:drug effects; D008297:Male; D008550:Melatonin / Q000008:administration & dosage* / Q000494:pharmacology*; D012098:Reproduction / Q000187:drug effects*; D012611:Scrotum / Q000033:anatomy & histology / Q000187:drug effects; D012621:Seasons; D012661:Semen / Q000187:drug effects; D012756:Sheep / Q000097:blood* / Q000502:physiology* / Q000523:psychology; D013268:Stimulation, Chemical; D013739:Testosterone / Q000097:blood; D014416:Tunisia
chemical_list: D013739:Testosterone; D008550:Melatonin
keywords: libido; melatonin; semen; testosterone; young rams