119740 20240319081024.0 doi 10.1016/j.theriogenology.2022.08.035 sideral 130574 ART-2022-130574 eng Abecia, José Alfonso Universidad de Zaragoza (orcid)0000-0003-2827-3054 Exposure of rams in sexual rest to sexually activated males in spring increases plasma LH and testosterone concentrations 2022 Access copy available to the general public Unrestricted Eight stimulating rams, and twelve stimulated rams, were used to determine whether a similar endocrine response to the introduction of sexually active males in spring in a flock of ewes is observed in a flock of rams. The stimulating rams (n = 4) were induced into a sexually active state by exposure to 2 months of long days (16 h light/d) (15 December-15 February). At the end of the long-day period, rams were returned to the natural photoperiod. Control-stimulating rams (n = 4) were kept under the natural photoperiod. On April 20, stimulated rams were divided into 2 groups, and joined with activated (ACT; n = 6) or control stimulating rams (C; n = 6). On the day of ram introduction, stimulated rams were blood sampled for 8 h at 20-min intervals, from 4 h before to 4 h after ram introduction, and next day from 24 to 28 h after ram introduction, and analyzed for plasma LH concentrations, and 10, 20 and 30 days after ram introduction to measure plasma testosterone levels. Mean (±SEM) plasma LH concentrations (ng/ml) of stimulated rams were similar during the 4 h before stimulating-ram introduction (ACT: 0.59 ± 0.03; C: 0.53 ± 0.04; P > 0.05). The introduction of the photoperiod-treated stimulating rams increased LH concentrations of stimulated rams during the 4 h after their introduction (1.14 ± 0.37) compared with the C group (0.51 ± 0.03; P < 0.05), especially during the first hour (ACT: 0.93 ± 0.16; C: 0.49 ± 0.03; P < 0.05), and during the blood sampling period 24–28 h after ram introduction (0.75 ± 0.07 vs. 0.58 ± 0.04; P < 0.05). Before the introduction of stimulating rams, the LH pulse frequencies and amplitudes did not differ between groups; however, LH pulsatility was higher at 4 h (0.58 ± 0.11 pulses/h; P < 0.05), and had trend to be higher 24 h (0.50 ± 0.06) (P = 0.10) after the introduction of the photoperiod-treated stimulating rams compared with the control-stimulating rams (0.29 ± 0.08 and 0.29 ± 0.10, respectively). As for LH pulses, there was an effect of group (P < 0.05) on LH amplitude, which presented a trend to be higher in ACT rams 4 h after ram introduction (1.68 ± 0.30; P < 0.10) and higher 24 h (1.07 ± 0.08; P < 0.05) after ram introduction, compared with LH amplitudes of C rams (0.71 ± 0.06 and 0.82 ± 0.07, respectively). Plasma testosterone concentrations of rams exposed to photoperiod-treated activated rams were higher than those of rams exposed to control-stimulating rams, at 4 h, 20 and 30 days after ram introduction (P < 0.05). In conclusion, sexually active rams in spring are able to stimulate LH and testosterone secretion of other rams in sexual rest, a phenomenon we called “ram-to-ram effect". info:eu-repo/semantics/openAccess by http://creativecommons.org/licenses/by/3.0/es/ 2.8 2022 VETERINARY SCIENCES 17 / 144 = 0.118 2022 Q1 T1 REPRODUCTIVE BIOLOGY 19 / 31 = 0.613 2022 Q3 T2 0.764 2022 Animal Science and Zoology 2022 Q1 Small Animals 2022 Q1 Food Animals 2022 Q1 Equine 2022 Q1 5.6 2022 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Canto, Francisco Keller, Matthieu Palacios, Carlos Chemineau, Philippe Delgadillo, José Alberto 2008 700 Universidad de Zaragoza Dpto. Produc.Animal Cienc.Ali. Área Producción Animal 192 (2022), 116-121 1879-3231] THERIOGENOLOGY 0093-691X 1023291 http://zaguan.unizar.es/record/119740/files/texto_completo.pdf Versión publicada 2514540 http://zaguan.unizar.es/record/119740/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:119740 articulos driver 2024-03-18-16:34:58 ARTICLE