A comparison of the efficiency of melatonin treatments in advancing oestrus in ewes

English, J.; Poulton, A. L.; Arendt, J; Symons, A. M.

doi:10.1530/jrf.0.0770321

Cited by 121 publications

(60 citation statements)

References 12 publications

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“…Melatonin can be used alone, or combined with other hormonal treatments, after an artificial light (photoperiodic) treatment. In several studies concerning ewes of different breeds, melatonin administration has been found to advance the onset of reproductive activity (Arendt et al, 1983;Karsch et al, 1984;English et al, 1986); furthermore, melatonintreated ewes appeared to have better oocyte quality and higher ovulation and conception rates (Stellflug et al, 1988;Kouimtzis et al, 1989;Tsiligianni et al, 2009).…”

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confidence: 98%

Testicular function and semen characteristics of Awassi rams treated with melatonin out of the breeding season

Faigl

Keresztes

Kulcsár

et al. 2009

Acta Veterinaria Hungarica

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The objective of this study was to evaluate the effect of long-term melatonin treatment applied during the non-breeding season on semen characteristics, endocrine function of testicles and baseline level of insulin-like growth factor-I (IGF-I) in Awassi rams kept in the temperate continental zone of Europe and used as semen donors in an artificial insemination (AI) programme. On 23 February (day 0), slow-release melatonin implants were inserted subcutaneously into rams (n = 8). Control animals (n = 8) received no treatment. In both groups, basic semen parameters (concentration, total motility, fast and slow forward motility, morphology), GnRH-induced testosterone response and basal IGF-I concentration were evaluated on days 0, 47 and 71. No differences were found in concentration of spermatozoa, total motility, and numbers of spermatozoa with fast and slow progressive motility and normal/abnormal morphology between the melatonintreated and the control group. However, in melatonin-treated animals, basal and GnRH-induced testosterone levels were slightly elevated on day 47 and became significantly higher on day 71 (P < 0.05) as compared to controls. There was no difference in plasma IGF-I levels between the groups. In conclusion, slow-release melatonin applied during the non-breeding season improves testicular testosterone production but does not influence the semen characteristics and the IGF-I level of semen donor Awassi rams used in an AI programme and kept in the temperate continental zone of Europe.

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mentioning

confidence: 98%

Testicular function and semen characteristics of Awassi rams treated with melatonin out of the breeding season

Faigl

Keresztes

Kulcsár

et al. 2009

Acta Veterinaria Hungarica

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“…The date of onset of ovarian activity was taken as the date before progesterone rose above 0.5 ng·mL -1 in two consecutive plasma samples [20]. The date of the end of ovarian activity was the first sample date with progesterone concentrations lower than 0.5 ng·mL -1 followed by basal levels in successive plasma samples.…”

Section: Discussionmentioning

confidence: 99%

Seasonal ovulatory activity and plasma prolactin concentrations in the Spanish ibex(Capra pyrenaica hispanica) maintained in captivity

Santiago-Moreno¹,

Gómez-Brunet²,

González-Bulnes³

et al. 2003

Reprod. Nutr. Dev.

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-Seasonal changes in ovulatory activity, assessed by the measurement of plasma progesterone and plasma prolactin concentrations were monitored in 10 Spanish ibex females captured in the National Wildlife Reserve of Sierra Nevada (South Spain, 37º N). Five of the 10 female ibex showed ovulatory activity with a mean (± s.e.m.) duration of the oestrous cycle of 19.4 ± 1 days (range: 17-23 days). On average, the five cyclic females weighed 28 ± 0.9 kg. Progesterone cycles occurred only in animals older than 4 years of age. Ovulatory activity extended from December to January. The duration of the breeding season was 43.2 ± 7.7 days. Ibex females younger than 4 years of age had a body weight lower (P < 0.01) than that of adults and none of them displayed ovulations. Plasma concentrations of prolactin levels were significantly affected by season (P < 0.05), following a trend that was roughly parallel to daylength. The highest values occurred in the spring (119.7 ± 21.4 ng·mL -1 ) and the summer (139.3 ± 19.8 ng·mL -1 ), the lowest values in the autumn (26 ± 7.4 ng·mL -1 ) and in the winter (19.7 ± 3.2 ng·mL -1 ). Our results showed a very restricted breeding season, despite the fact that the Spanish ibex originates from and lives in a temperate latitude, revealing a remarkably good adaptation to the harsh climatic and nutritional conditions of their mountainous habitat.breeding season / ovulation / progesterone

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“…A switch from long days to short days leads to an increase in the duration of melatonin secretion and this results in a resurgence of reproductive activity and the onset of the new breeding season. The administration of exogenous melatonin in the afternoon to sheep exposed to long days, which extends the exposure to melatonin, causes early onset of ovarian activity in ewes similar to that produced by transfer to short days (Kennaway et al, 1982;English et al, 1986;Wigzell et al, 1988). The protocol of administering melatonin in the afternoon to photo-inhibited rams was used in the current study to test the effectiveness of ML23 as a melatonin antagonist.…”

Section: Introductionmentioning

confidence: 99%

Test of ML23 as an antagonist to the effects of melatonin in the ram

Lincoln¹,

Kelly²

1989

Reproduction

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Summary. In Exp. 1, four groups of 8 yearling Soay rams were housed under long days (16L:8D) to induce reproductive quiescence and were treated daily for 12 weeks with: (I) vehicle (2 or 4 ml 50% ethanol/water), (II) ML23 (2 mg), (III) melatonin (2 mg) and (IV) melatonin and ML23 (2 mg of each). All treatments were given orally in the mid-light phase. In the rams receiving melatonin (Group III) there was an earlier increase in the plasma concentrations of FSH and testosterone and regrowth of the testes compared to the controls (time to maximum testicular diameter: 10\m=.\0 \ m=+-\ 0\m=.\5and 15\m=.\3\m=+-\1\m=.\2 weeks). These differences were reversed after the end of the 12-week treatments when rapid testicular regression occurred in melatonin-treated rams but not in the controls. In the group receiving ML23 and melatonin (Group IV), there was early reactivation and regression of the reproductive axis as in the melatonin group (testis max. 9\m=.\9\ m=+-\ 0\ m=. \ 7 and 10\m=.\0\ m=+-\ 0\ m=. \ 5weeks) while in the group receiving ML23 alone (Group II) there was a slower redevelopment and regression as in the controls (testis max. 15\m=.\7\m=+-\1\m=.\1and 15\m=.\3\m=+-\1\m=.\2 weeks). The comparison between the 4 groups in the changes in the blood concentrations of prolactin, voluntary food intake and total body weight also indicated that the treatment with ML23 failed to modify the effect of melatonin (combined treatment vs melatonin) or the effect of the long day photoperiod (ML23 vs vehicle).In Exp. 2, a more soluble derivative of ML23 (called ML23-lysine) was tested in two groups of 4 adult Soay rams which were housed under long days (16L:8D) and treated daily for 12 weeks, as above with: (I) melatonin (2 mg) and (II) melatonin (2 mg) and ML23-lysine (4 mg). In both groups there was a similar reactivation and regression of the testes with no significant differences between the two treatments.The overall results illustrate that the treatments with melatonin in this protocol were effective at influencing a wide range of reproductive and non-reproductive measures in the ram, but that ML23 was unable to antagonize these biological effects of melatonin.

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A comparison of the efficiency of melatonin treatments in advancing oestrus in ewes

Cited by 121 publications

References 12 publications

Testicular function and semen characteristics of Awassi rams treated with melatonin out of the breeding season

Testicular function and semen characteristics of Awassi rams treated with melatonin out of the breeding season

Seasonal ovulatory activity and plasma prolactin concentrations in the Spanish ibex(Capra pyrenaica hispanica) maintained in captivity

Test of ML23 as an antagonist to the effects of melatonin in the ram

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