Melatonin treatment prior to the normal breeding season increases fetal number in United Kingdom sheep flocks

2009 ◽  
Vol 182 (2) ◽  
pp. 198-202 ◽  
Author(s):  
P.R. Scott ◽  
N.D. Sargison ◽  
A.I. Macrae ◽  
M.R. Gough
Keyword(s):  
United Kingdom ◽  
Breeding Season ◽  
Melatonin Treatment

The effect of melatonin treatment during the seasonal anoestrus on the superovulatory response and embryo production of high-prolificacy Rasa Aragonesa ewes before culling

2003 ◽  
Vol 2003 ◽  
pp. 82-82
Author(s):  
F. Forcada ◽  
J.A. Abecia ◽  
J.A. Valares
Keyword(s):  
Embryonic Development ◽  
Breeding Season ◽  
Litter Size ◽  
Direct Effect ◽  
Ovulation Rate ◽  
Corpora Lutea ◽  
Melatonin Treatment ◽  
Embryo Production ◽  
Spring Equinox

The efficacy of melatonin implants inserted around the spring equinox to improve fertility and ovulation rate or litter size in Mediterranean ewes has been previously reported (Chemineau et al., 1996; Forcada et al., 2002a.), indicating the ability of the hormone to regulate the hypothalamic activity (Viguié et al., 1995). Moreover, a direct effect of melatonin on corpora lutea and embryonic development has been also reported (Wallace et al., 1988; Abecia et al., 2002). The use of prolific Rasa Aragonesa (RA) ewes (a Mediterranean breed) before culling as embryo donors has been previously tested in the breeding season (Forcada et al., 2002b.). The aim of this experiment was to improve embryo production during the seasonal anoestrus period in selected superovulated RA ewes at the end of their reproductive lives through the use of melatonin.

Effect of melatonin treatment on semen parameters and endocrine function in Black Racka rams out of the breeding season

2014 ◽  
Vol 116 (2-3) ◽  
pp. 192-198 ◽  
Author(s):  
I. Egerszegi ◽  
P. Sarlós ◽  
J. Rátky ◽  
L. Solti ◽  
V. Faigl ◽  
...  
Keyword(s):  
Breeding Season ◽  
Endocrine Function ◽  
Semen Parameters ◽  
Melatonin Treatment

Effect of melatonin on the peripheral concentrations of LH and progesterone after oestrus, and on conception rate in ewes

1988 ◽  
Vol 119 (3) ◽  
pp. 523-530 ◽  
Author(s):  
J. M. Wallace ◽  
J. J. Robinson ◽  
S. Wigzell ◽  
R. P. Aitken
Keyword(s):  
Breeding Season ◽  
Pulse Generator ◽  
Ovulation Rate ◽  
Melatonin Treatment ◽  
Embryo Survival ◽  
Plasma Progesterone ◽  
Progesterone Secretion ◽  
Endocrine Status ◽  
Increased Activity ◽  
Intra Uterine Insemination

ABSTRACT It has previously been shown that administration of the indoleamine melatonin to advance the breeding season of ewes is also associated with an increase in ovulation rate and subsequent litter size. Experiment 1 assessed whether, in ewes receiving melatonin to advance the breeding season, the indoleamine acts directly on the corpus luteum to enhance progesterone secretion or indirectly through increased activity of the hypothalamic pulse generator. Six ewes received 3 mg melatonin orally at 15.00 h daily from 22 March onwards, six were induced to ovulate during mid-anoestrus following withdrawal of a progestagen pessary and injection of exogenous gonadotrophin and six acted as naturally ovulating controls. First overt oestrus occurred between 17 May and 8 July in melatonin-treated ewes, between 21 October and 3 January in control ewes and on 8 July in all induced ewes. On days 2 and 10 after the first overt oestrus, melatonin-treated ewes had pulsatile LH activity characteristic of that measured in control ewes ovulating naturally during the breeding season. There was an absence of any pulsatile LH activity in the induced ewes. Progesterone concentrations between days 7 and 12 following oestrus were significantly higher in melatonin-treated than in control and induced ewes, suggesting a luteotrophic role for melatonin. Experiment 2 was carried out to determine whether administration of melatonin commencing after induced ovulation and insemination would alter the endocrine status of the ewe and thereby influence the establishment of pregnancy and embryo survival. Thirty-two anoestrous ewes were induced to ovulate on 29 June. Starting 24 h after intra-uterine insemination, 16 ewes were given melatonin daily for 60 days and 16 acted as controls. Daily LH concentrations were higher in melatonin-treated than in control ewes from days 2 to 22 after oestrus, while prolactin concentrations declined in melatonin-treated ewes over the same period. Plasma progesterone concentrations were enhanced in melatonin-treated ewes between days 4 and 9 following oestrus, yet ovulation rates were the same as for controls. Successful pregnancies occurred in 0·56 control (9 of 16) and 0·69 melatonin-treated (11 of 16) ewes. For these ewes the number of fetuses surviving to term as a proportion of ovulation rate was 0·43 and 0·51 for the control and melatonin treatment respectively. J. Endocr. (1988) 119, 523–530

Duration of melatonin treatment and ovarian activity in ewes

1988 ◽  
Vol 1988 ◽  
pp. 92-92
Author(s):  
S. Wigzell ◽  
J.J. Robinson ◽  
J.M. Wallace ◽  
R.P. Aitken
Keyword(s):  
Breeding Season ◽  
Ovarian Activity ◽  
Similar Reaction ◽  
Melatonin Treatment ◽  
Oral Dosing ◽  
Starting Time ◽  
Highly Effective ◽  
Natural Photoperiod ◽  
The Mean

Daily oral dosing in mid afternoon with 3 mg of the indoleamine, melatonin, from early June onwards is highly effective in advancing the breeding season of both Greyface and Scottish Blackface ewes kept under a natural photoperiod; the mean reaction interval from initial dosing to the onset of ovarian activity in Scottish Blackface ewes being around 65 days compared with 110 days for untreated controls (Robinson et al 1985). Advancing the starting time for the melatonin treatment to mid-March gave a similar reaction interval with behavioural oestrus occurring in late May/early June (Wigzell et al 1986a). Following this reversal of the breeding season by melatonin, continued melatonin treatment in unmated ewes resulted in a period of oestrous cyclicity lasting 4 to 5 months. Thereafter the ewes became refractory to melatonin and returned to anoestrus at a time when untreated controls were commencing ovarian activity (Wigzell et al 1986b). These observations prompted us to investigate the effects of different durations of melatonin treatment on ovarian activity.

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

2009 ◽  
Vol 57 (4) ◽  
pp. 531-540 ◽  
Author(s):  
Vera Faigl ◽  
Mónika Keresztes ◽  
Margit Kulcsár ◽  
Sándor Nagy ◽  
Zsuzsanna Keresztes ◽  
...  
Keyword(s):  
Breeding Season ◽  
Slow Release ◽  
Endocrine Function ◽  
Semen Parameters ◽  
Control Group ◽  
Melatonin Treatment ◽  
Semen Characteristics ◽  
Igf I ◽  
Semen Donor

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 melatonin-treated 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.

Effects of melatonin implantation on the fertility potentials of Kivircik and Charollais ewes and rams during the non-breeding season

2017 ◽  
Vol 20 (3) ◽  
pp. 501-506 ◽  
Author(s):  
M. Cevik ◽  
C. Yilmazer ◽  
A. Kocyigit
Keyword(s):  
Pregnancy Rate ◽  
Breeding Season ◽  
Reproductive Performance ◽  
Reproductive Potential ◽  
Testicular Volume ◽  
Melatonin Treatment ◽  
Scrotal Circumference ◽  
Estrus Response

AbstractThis study examined the effect of melatonin implantation during the non-breeding season on the reproductive performance of ewes and the testicular dimensions of rams. In seasonally anestrus Kivircik and Charollais ewes and rams were subjected to melatonin. Estrus response was significantly higher in treated than control ewes of both breeds (p<0.001). The pregnancy rate was significantly lower (p<0.001) in the control than in the treated animals. The twinning rate was significantly lower in melatonin implanted Kivircik than Charollais ewes (p<0.05). The testicular dimensions after 42 days of melatonin treatment increased in both breeds. Scrotal length (SL) increased in Kivircik and Charollais rams (p<0.01). The increase in scrotal circumference (SC) was more marked in the Charollais (P<0.01) than in the Kivircik rams. There was a large increase in testicular volume (TV) in both Kivircik (p<0.01) and Charollais (p<0.001) rams. This study shows that melatonin implants can be applied to induce estrus in ewes approximately four months earlier than breeding season. Melatonin implantation in the non-breeding season significantly increased testicular dimensions in Kivircik and Charollais rams thus increasing their reproductive potential.

The effect of the oral administration of melatonin at two times of the year on ovarian activity in ewes

1986 ◽  
Vol 1986 ◽  
pp. 53-53 ◽  
Author(s):  
S. Wigzell ◽  
J. J. Robinson ◽  
R. P. Aitken ◽  
W. A. C. McKelvey
Keyword(s):  
Oral Administration ◽  
Breeding Season ◽  
Daily Administration ◽  
Ovarian Activity ◽  
Melatonin Treatment ◽  
Breeding Activity ◽  
Normal Period

It has previously been shown (Robinson et al., 1985) that the normal breeding season of Greyface and Scottish Blackface ewes can be advanced by the daily administration of the indoleamine melatonin; the administration of the melatonin beginning midway during the anoestrous period. If melatonin is administered towards the end of the normal breeding season, oestrous activity can be extended, but only for a period of about six weeks until the ewe becomes refractory to the melatonin treatment (Nett and Niswender, 1981). There is no information on the administration of melatonin at the beginning of the anoestrous period.In the following experiments we report results for the influence on the subsequent breeding activity of Greyface ewes of the oral administration of melatonin at the beginning of their normal period of anoestrus. We also report the results of an investigation on the effects of melatonin in advancing the breeding season of Scottish Blackface ewes maintained on either a high or low plane of nutrition. The experiments were carried out under natural daylength conditions at 57°N.

Ovulatory activity, hormonal induction of ovulation and fertility of young Cashmere and Angora female goats in a temperate environment

1994 ◽  
Vol 6 (6) ◽  
pp. 737 ◽  
Author(s):  
AJ Ritar ◽  
JA Robertson ◽  
G Evans
Keyword(s):  
Breeding Season ◽  
Hormonal Treatment ◽  
Breeding Period ◽  
Melatonin Treatment ◽  
Stratified Sample ◽  
Temperate Environment ◽  
Temperate Pastures ◽  
Almost All ◽  
Pregnant Mare Serum Gonadotrophin

Reproductive parameters of young Cashmere and Angora goats born between 1988 and 1990 and grazed on temperate pastures in southern Australia were examined with a view to reducing the age of first breeding. Females born in August or October of 1989 and 1990 were examined each month by laparoscopy to determine natural ovulatory activity when 6-19-months old. Cashmeres commenced ovulating as young as 7 months of age or as light as 12 kg. Almost all Cashmeres were ovulating by 8-10 months of age at a liveweight of at least 18 kg, and their breeding season extended from April to October. By comparison with Cashmeres, Angoras grew more slowly, fewer ovulated, they commenced ovulation later, their ovulation rates were lower and their breeding season was shorter. A stratified sample of these females was injected with 200 I.U. or 400 I.U. of pregnant mare serum gonadotrophin (PMSG) after treatment with controlled internal drug release (CIDR) devices for 16-18 days to induce ovulation at 6, 9, 12, 15 and 19 months of age. Ovulation rates after CIDR-PMSG treatment were higher for Cashmeres than for Angoras and tended to be higher for females injected with 400 I.U. PMSG than 200 I.U. PMSG. The proportion of females remaining anovulatory after exogenous hormonal treatment was higher for Angoras than for Cashmeres (38% and 10% respectively) but it was not affected by the dose of PMSG or age. For kids born in 1989, the kidding rates to insemination (with follow-up mating) after CIDR-PMSG treatment for 8-month-old and 20-month-old Cashmeres (in the breeding season) were similar (75.0% and 83.8% respectively) but the rate for 14-month-old Cashmeres was only 10.0% (in the non-breeding period). The kidding rates for Angoras bred at 8, 14 and 20 months of age were 8.4%, 20.0% and 30.0% respectively. Ovulatory activity and fertility in the non-breeding period, with or without CIDR-PMSG treatment, did not improve with melatonin treatment.

Effects of melatonin and a dopamine agonist and antagonist on seasonal changes in voluntary intake, reproductive activity and plasma concentrations of prolactin and tri-iodothyronine in red deer hinds

1990 ◽  
Vol 125 (2) ◽  
pp. 241-249 ◽  
Author(s):  
J. A. Milne ◽  
A. S. I. Loudon ◽  
A. M. Sibbald ◽  
J. D. Curlewis ◽  
A. S. McNeilly
Keyword(s):  
Dopamine Agonist ◽  
Breeding Season ◽  
Red Deer ◽  
Plasma Concentrations ◽  
Control Group ◽  
Rapid Decline ◽  
Dopamine Antagonist ◽  
Plasma Prolactin ◽  
Melatonin Treatment ◽  
The Mean

ABSTRACT Three experiments were conducted in the period between July and November with non-lactating red deer hinds to describe the effects of treatment with melatonin during this period on voluntary food intake (VFI), the onset of the breeding season, coat changes and plasma concentrations of prolactin and tri-iodothyronine (T3), and to examine whether prolactin mediated the observed effects. In experiment 1, eight animals were treated orally each day with either 10 mg melatonin at 16.00 h or 10 mg melatonin at 16.00 h plus 10 mg domperidone (a dopamine antagonist) given twice daily for 120 days from July; eight animals were maintained as controls. In experiment 2, the same numbers of animals per treatment were used to compare treatments in which 10 mg melatonin or 20 mg bromocriptine (a dopamine agonist) were given orally each day at 16.00 h for 119 days from late June and compared with an untreated control group. In experiment 3, six animals were treated daily for 105 days from mid August with 5 mg domperidone given i.m. and compared with six control animals. In experiments 1 and 2, the VFI of control animals reached a peak in late August and thereafter declined. Melatonin-treated animals showed a similar pattern but the peak in VFI was significantly (P<0·05) advanced by 2 weeks compared with controls, although the VFIs of both groups were similar in November. The mean date of onset of the breeding season of the melatonin-treated animals was advanced significantly (P < 0·05) by 23 days in both experiments and the coats of these animals had less undercoat and were pale coloured and patchy compared with the controls. The changes in VFI, coat and the onset of the breeding season were associated with the rapid decline in plasma prolactin concentration after the start of the melatonin treatment and significantly (P<0·01) lower plasma T3 concentrations than those of control animals. In experiments 1 and 3, plasma prolactin concentrations in animals treated with domperidone were higher than those of controls for periods of 2–3 weeks. These short-term increases in plasma prolactin concentration were not associated with changes in VFI, coat or onset of the breeding season compared with controls. In experiment 2, the pattern of decline in plasma prolactin concentrations was the same in bromocriptine-treated animals as in the melatonin-treated animals; plasma T3 concentrations were also similar in the two groups. The pattern of change in VFI over time in bromocriptine-treated animals was significantly (P<0·05) different from that of melatonin-treated animals and there was also a reduced amount and length of winter coat in the bromocriptine-treated animals. The mean date of onset of the breeding season in bromocriptine-treated animals was not significantly different from that of controls. It was concluded that a reduction in plasma prolactin concentration induced by bromocriptine produced different effects from that induced by melatonin treatment and that the effects of melatonin are unlikely to be induced through changes in contemporary plasma prolactin concentrations. Journal of Endocrinology (1990) 125, 241–249

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