Presence of photoperiod-melatonin-induced, sexually-activated rams in spring advances puberty in autumn-born ewe lambs

Abecia, J.A.; Chemineau, Philippe; Gómez, Andrea; Keller, Matthieu; Forcada, F.; Delgadillo, J.A.

doi:10.1016/j.anireprosci.2016.04.011

Cited by 31 publications

(27 citation statements)

References 21 publications

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“…In this study, exposure to 2 months of long days before a return to the natural photoperiod increased testosterone secretion in rams, but exogenous melatonin did not have a significant effect, and rams exposed to the artificial photoperiod served the most ewes in the tests, and the melatonin implants were most effective in rams that had been exposed to the natural photoperiod. The testosterone profiles, which were similar to those in an earlier study (Abecia et al., ), showed that, in rams exposed to artificially long days, plasma testosterone concentrations decreased after 30 day of exposure. Testosterone concentrations increased 30 day after the return to the natural photoperiod (March‐April), at the beginning of the natural sexual refractory period.…”

Section: Discussionsupporting

confidence: 88%

“…In a recent study, we found that prolonged continuous exposure to sexually active rams that had been stimulated by artificial photoperiod and melatonin implants prolonged ovarian activity and increased oestrous expression in Mediterranean ewes in spring (Abecia et al., ). Furthermore, the introduction at weaning of those sexually active rams advanced the resumption of oestrous activity in adult ewes in spring after weaning at the end of the breeding season (Abecia et al., ), and their presence advanced puberty in autumn‐born ewe lambs (Abecia et al., ). That combination of artificial photoperiod and melatonin treatment stimulates testosterone secretion in Rasa Aragonesa rams in spring (Abecia et al., ).…”

Section: Introductionmentioning

confidence: 99%

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Extended day length in late winter/early spring, with a return to natural day length of shorter duration, increased plasma testosterone and sexual performance in rams with or without melatonin implants

Abecia

Chemineau

Keller

et al. 2017

Reprod Domestic Animals

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Sixteen rams were used to quantify the effects of long days, imposed during late winter/early spring, with or without exogenous melatonin, on plasma testosterone concentrations and ram serving capacity. Rams were assigned to two groups: photoperiod-treated rams (Artificial Photoperiod, AP; n = 8), exposed to 2 months of long days (16 hr of light/day) between 22 December and 22 February, and control rams (Natural Photoperiod, NP; n = 8). At the end of the long-day period, AP rams were returned to the natural photoperiod, and each ram in the two groups either did (+M) or did not (-M) receive three subcutaneous melatonin implants. Four groups were created as follows: AP+M (n = 4), AP-M (n = 4), NP+M (n = 4) and NP-M (n = 4). Thirty days after of the onset of photoperiodic treatment, AP rams (13.5 ± 2.8 ng/ml) had significantly (p < .05) lower testosterone levels than NP rams (36.7 ± 1.0), and similar differences were not apparent at the end of the photoperiod treatment. A month later, AP rams (24.3 ± 7.9) had higher (p < .10) testosterone levels than NP rams (13.1 ± 5.0), with no effect of melatonin treatment. Fifty days after melatonin implantations, rams were exposed for 20 min to three oestrous ewes. AP rams (2.50 ± 0.42) exhibited significantly (p < .05) more serves than did NP rams (1.11 ± 0.39), and melatonin treatment had no significant effect; however, the interaction between treatments was significant. Time to first serve was significantly (p < .05) shorter in AP (2.30 ± 1.20 min) than it was in NP rams (5.58 ± 0.68 min). In conclusion, exposure to 2 months of long days in late winter/early spring, with a return to natural day length of shorter duration, increased plasma testosterone concentrations and sexual performance in rams with or without exogenous melatonin. This particular management is an option if a non-hormonal reproductive strategy is scheduled; yet, if the use of exogenous hormones is feasible, melatonin implants increase the mating efficiency of rams.

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Section: Discussionsupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Extended day length in late winter/early spring, with a return to natural day length of shorter duration, increased plasma testosterone and sexual performance in rams with or without melatonin implants

Abecia

Chemineau

Keller

et al. 2017

Reprod Domestic Animals

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“…In ewes with induced oestrus, good results have been reported in Merino breeds with fresh semen ‐56.7%‐ (Fernandez‐Abella, Preve, & Villegas, ), ‐65%‐ (Fernandez et al., ) or chilled semen at 15°C in the Lacaune breed 66.7% (Rocha et al., ). Under these conditions and in Spanish breeds, fertility is highly variable—Aragonesa: 45% (Abecia et al., ), Churra: 31% (Anel et al., ), Assaf: 39% (Álvarez, Chamorro, et al., ; Álvarez, Tamayo‐Canul, et al. ) and Castellana: 45.5% (Kaabi et al., ).…”

Section: Cervical Insemination: a Classic To Improvementioning

confidence: 99%

Current challenges in sheep artificial insemination: A particular insight

Álvarez

Anel-López

Boixo

et al. 2019

Reprod Domestic Animals

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Ovine artificial insemination (OAI) is not commonly performed because of specific problems related to semen application techniques, leading to highly variable results.The ideal methodology (frozen-thawed semen/vaginal route) is unfeasible under field conditions due to the cervix morphology of the ewe, which prevents the process of intrauterine insemination necessary to obtain acceptable results. Currently, OAI commercial programmes use superficial cervical insemination, CAI (vaginal), with chilled semen (15°C) and intrauterine insemination, LAI (laparoscopic), with frozen-thawed semen. The ability to improve upon these contrasting techniques may be derived from examining certain poorly studied factors such as insemination time, productive state of females and alternatives of seminal preservation, some of which we reviewed in this work. This interim solution will remain in use until AI by the vaginal route with frozen-thawed semen is developed, but it poses new challenges in optimizing the freezing of the sperm and adapting the cervical (CAI) and/or transcervical intrauterine AI (TCAI). In this review, we address the current problems and evaluate their methodological (mechanical) and chemical (dilation) alternatives. Currently, TCAI is a methodologically complex technique with poor fertility results, so further studies are needed to improve the logistics of this procedure and the results of its application. K E Y W O R D SAI, cervix, cryopreservation, ovine, sperm, transcervical | 33 ALVAREZ Et AL.

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“…Consequently, it inhibits LH and FSH secretion. This explains how photoperiod regulates reproductive function in seasonal species [17].…”

Section: At Physiological Levelmentioning

confidence: 92%

Role of Hormones in the Control of Reproductive Physiology and Reproductive Behavior

Nguyen¹

2019

IJBMR

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In multicellular organisms, intercellular mediators such as hormones or growth factors and morphogens play primary roles in development and reproduction. Evolution of the signaling pathways in which these mediators are involved has thus played an important role in the appearance and success of these species. There are many reproductive modes and behaviours in the animal kingdom. A reproductive behaviour can be defined as all the actions taken by an organism toward the generation of one or more other organism that possesses at least some of its genetic patrimony. From a strict evolutionary point of view, the goal of an organism is to spread its genetic patrimony as much as possible in the next generations of its kind. This egoistic behaviour typically benefits for the entire species since the individuals spreading the most their genetic patrimony is generally those with the best genes and are thus helping their species to be the most fitted possible. In the present review, I briefly describe the implication of hormones in the control of mammals Reproduction and in their Sexual Behavior. In addition, since most multicellular organisms exhibit sexual reproduction, I also take into account hormonal control of reproduction together with sexual behavior.

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Presence of photoperiod-melatonin-induced, sexually-activated rams in spring advances puberty in autumn-born ewe lambs

Cited by 31 publications

References 21 publications

Extended day length in late winter/early spring, with a return to natural day length of shorter duration, increased plasma testosterone and sexual performance in rams with or without melatonin implants

Extended day length in late winter/early spring, with a return to natural day length of shorter duration, increased plasma testosterone and sexual performance in rams with or without melatonin implants

Current challenges in sheep artificial insemination: A particular insight

Role of Hormones in the Control of Reproductive Physiology and Reproductive Behavior

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