88541 20230914083245.0 doi 10.1016/j.heliyon.2020.e03529 sideral 117269 ART-2020-117269 eng Abecia, José A. Universidad de Zaragoza (orcid)0000-0003-2827-3054 Light-induced sexually active rams provoke LH preovulatory surges and enhances LH concentrations in ewes after progestagen treatment 2020 Access copy available to the general public Unrestricted The effect of the introduction of sexually active rams in spring on LH secretion in ewes after progestagen treatment has been studied. Two rams were induced into a sexually active state by exposure to 2 months of long days (16 h of light/d) from 1 January (SAR), and another 2 rams were exposed to the natural photoperiod, so that they were not sexually activated in spring (control; C). At the end of the long-day period, rams were returned to natural photoperiod conditions. Fifteen ewes synchronized in estrus by intravaginal sponges were assigned to three groups at sponge withdrawal (hour 0): SAR (n = 5), exposed to SAR rams; C (n = 5), exposed to C rams, and ISO (n = 5), kept isolated from rams. Twenty-four hours after pessary removal (hour 0), rams were introduced into the SAR and C groups. Three SAR ewes presented preovulatory LH surges; the proportion was significantly (P < 0.05) higher in this group (3/5) than in the others (C: 0/5, ISO: 0/5). SAR introduction induced a more marked (P < 0.05) increase in mean LH plasma concentrations (before rams: 1.34 ± 0.19; after rams: 6.94 ± 2.66 ng/ml) than C (before: 0.96 ± 0.29; after: 3.60 ± 1.44) or ISO (before: 1.26 ± 0.42; after: 2.14 ± 1.36) groups, and significantly (P < 0.05) higher plasma LH levels after ram introduction. In conclusion, only light-treated sexually activated rams induced LH preovulatory surges in ewes in the seasonal anestrus, when ewes are synchronized with progestagen treatment in the absence of eCG. info:eu-repo/semantics/openAccess by-nc-nd http://creativecommons.org/licenses/by-nc-nd/3.0/es/ 0.455 2020 Multidisciplinary 2020 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Keller, Matthieu Chemineau, Philippe Delgadillo, José A. 2008 700 Universidad de Zaragoza Dpto. Produc.Animal Cienc.Ali. Área Producción Animal 6, 3 (2020), e03529 1-4 Heliyon Heliyon 2405-8440 610179 http://zaguan.unizar.es/record/88541/files/texto_completo.pdf Versión publicada 47206 http://zaguan.unizar.es/record/88541/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:88541 articulos driver 2023-09-13-10:50:04 ARTICLE