Photoperiodic regulation of reproduction in the male silver fox (Vulpes vulpes)

Forsberg, M.; Fougner, J. A.; Hofmo, P. O.; Madej, Malgorzata; Einarsson, E. J.

doi:10.1530/jrf.0.0870115

Cited by 15 publications

(16 citation statements)

References 10 publications

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“…This study shows that administration of melatonin to silver fox males during long days influenced secretion of testosterone, prolactin and thyroxine in the same way as decreasing photoperiod does (Joffre & Joffre, 1975;Joffre, 1976;Maurel & Boissin, 1981;Maurel et al, 1984;Forsberg et al, 1989). These findings strengthen the hypothesis that melatonin is the hormonal signal transducing photoperiodic information in the silver fox, as described for other species.…”

Section: Discussionsupporting

confidence: 83%

“…Earlier experiments have shown that the reproductive cycle as well as the moulting cycle of the silver fox (Vulpes vulpes) male can be influenced by changes in photoperiod (Forsberg et al, 1989) and melatonin administration (Connor, 1988;Forsberg et al, 1990). Under natural daylight con¬ ditions plasma concentrations of testosterone and thyroxine show distinct seasonal variations (Joffre & Joffre, 1975;Joffre, 1976;Maurel & Boissin, 1981), and prolactin secretion increases during and after the mating season (Maurel et al, 1984).…”

Section: Introductionmentioning

confidence: 99%

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Effects of melatonin implants on plasma concentrations of testosterone, thyroxine and prolactin in the male silver fox (Vulpes vulpes)

Forsberg

Madej²

1990

Reproduction

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Summary. Melatonin administration in the form of slow-release implants advanced breeding activity in silver fox males when treatment began in June. Plasma testosterone concentrations were significantly higher in treated animals than in controls from September to November, whereas in February and March they were significantly lower. Plasma prolactin concentrations were significantly reduced immediately following melatonin treatment in June but increased to greater levels than control values and 'peaked' after 7 months. This 'peak' was associated with a rapid decrease in testosterone secretion. The normal seasonal spring rise in prolactin secretion was prevented by melatonin administration. Thyroxine values decreased and were significantly lower after 2 months of melatonin treatment.

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Section: Discussionsupporting

confidence: 83%

Section: Introductionmentioning

confidence: 99%

Effects of melatonin implants on plasma concentrations of testosterone, thyroxine and prolactin in the male silver fox (Vulpes vulpes)

Forsberg

Madej²

1990

Reproduction

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“…, ; Forsberg et al. ). However, male silver fox show testicular regression after 1 year of SP (Forsberg et al.…”

Section: Discussionmentioning

confidence: 98%

Effect of Refractoriness to Long Photoperiod on Sperm Production and Quality in Tomcats

Favre

Bonaura

Tittarelli

et al. 2012

Reprod Domestic Animals

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ContentsThe aim of this study was to assess whether refractoriness to long photoperiod (LP) could be reversed by subjecting tomcats to a period of short days. Our hypothesis was that photoperiod changes can avoid refractoriness and restore sperm quality and production to that before refractoriness. Tomcats (n = 6) were housed in a conditioned room with LP (12L: 12D) for 45 days of acclimation and then maintained under LP for 18 month. Then, tomcats were changed to a period of decreasing light at a rate of 8 min/day for 1 month. Tomcats stayed for 1 month with short photoperiod (SP; 8L: 16D) and then were switched back to a period of increasing light at a rate of 8 min/day for 1 month. The experiment was completed after tomcats remained in LP for 2 months. Toms were anaesthetized and semen samples were collected by electroejaculation every 2 weeks. Sperm parameters were evaluated in all ejaculates, and data were analysed by ANOVA. Motility, velocity, volume, sperm concentration, total sperm count, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher during LP compared with a refractory LP (p < 0.01). Likewise, velocity, viability, acrosome integrity, plasma membrane integrity and sperm morphology were higher in a LP compared with a SP (p < 0.05). On the other hand, motility, volume, concentration and total sperm count were similar between LP and SP (p > 0.20).Whereas motility, velocity, viability, acrosome integrity and plasma membrane integrity were similar in a refractory LP compared with SP (p > 0.05), volume, sperm concentration, total sperm count and sperm morphology were lower in a refractory LP compared with SP (p < 0.05). In conclusion, refractoriness and reduced sperm production and quality induced by a prolonged LP of 18 month can be restored after placing tomcats to a SP.

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“…Several methods are reported for semen collection in animals, as the use of an artificial vagina (Jalkanen, 1993), digital masturbation of the penile bulb (Forsberg et al, 1989) and electroejaculation (Watson, 1978;Wildt et al, 1983). With wild carnivores, electroejaculation is the method of choice due to the difficulty and risks involved in handling these animals.…”

Section: Electroejaculationmentioning

confidence: 99%

“…In these species, semen collection is usually performed by using an artificial vagina (Jalkanen, 1993) or digital masturbation (Forsberg et al, 1989). However, Barta and Jakubicka (1989) reported semen collection from foxes by electroejaculation under halothane anesthesia, which suggests the possibility of using this technique in those canids.…”

Section: Electroejaculationmentioning

confidence: 99%