Light-induced sexually active rams provoke LH preovulatory surges and enhances LH concentrations in ewes after progestagen treatment. Issue 3 (March 2020)

• Record Type: Journal Article
• Authors: Abecia, José A.; Keller, Matthieu; Chemineau, Philippe; Delgadillo, José A.
• Is Part Of: Heliyon. Volume 6:Issue 3(2020)
• Publication Date: 2020-03
• Subjects: Agricultural science -- Animal science -- Animal breeding -- Endocrinology -- Reproductive hormone -- Physiology -- Veterinary sciences -- Sheep -- LH -- Ram -- Sexual behavior -- Anestrus; Research -- Periodicals; Medical sciences -- Periodicals; Natural history -- Periodicals; Social sciences -- Periodicals; Earth sciences -- Periodicals; Physical sciences -- Periodicals; 507.2
• DOI: 10.1016/j.heliyon.2020.e03529
• Languages: English
• ISSNs: 2405-8440

Abstract

Abstract: 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. Abstract : Agricultural science; Animal science; Animal breeding; Endocrinology; Reproductive hormone; Physiology; Veterinary sciences; Sheep; LH; Ram; Sexual behavior; Anestrus