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Continuous light after a long-day treatment is equivalent to melatonin implants to stimulate testosterone secretion in Alpine male goats

  • J. A. Delgadillo (a1), L. I. Vélez (a1) and J. A. Flores (a1)


In rams, artificial long days followed by continuous light stimulate testosterone secretion during the non-breeding season. The objective of this study was to determine whether artificial long days followed by continuous light could stimulate testosterone secretion in Alpine bucks as well as in those exposed to long days followed by a melatonin treatment. All bucks were kept in shaded open pens. Control males were exposed to natural photoperiod conditions (n=5). Males of the two experimental groups were exposed to 2.5 months of long days from 1 December (n=5 each). On 16 February, one group of males was exposed to 24 h of light per day until 30 June; the other group was exposed to natural variations of photoperiod and received two s.c. melatonin implants. Testicular weight was determined every 2 weeks, and the plasma testosterone concentrations once a week. In the control and the two photoperiodic-treated groups, a treatment×time interaction was detected for testicular weight and plasma testosterone concentrations (P<0.001). In control bucks, testicular weight increased from January and peaked in June, whereas in both photoperiodic-treated groups, this variable increased from January, but peaked in April, when the values were higher than in controls (P<0.05). In the control group, plasma testosterone concentrations remained low from January to June, whereas in both photoperiodic-treated groups, this variable remained low from January to March; thereafter, these levels increased in both photoperiodic-treated groups, and were higher than controls in April and May (P<0.05). We conclude that continuous light after a long-day treatment stimulate testosterone secretion in Alpine male goats during the non-breeding season as well as the long days followed by a melatonin treatment. Therefore, continuous light could replace the implants of melatonin.


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Almeida, G and Pelletier, J 1988. Abolition of seasonal testis changes in the Ile-de-France ram by short light cycles: relationship to luteinizing hormone and testosterone release. Theriogenology 29, 681691.
Almeida, OFX and Lincoln, GA 1984. Reproductive photorefractoriness in rams and accompanying changes in the patterns of melatonin and prolactin secretion. Biology of Reproduction 30, 143158.
Barenton, B, Ravault, JP, Chabanet, C, Daveau, A, Pelletier, J and Ortavant, R 1988. Photoperiodic control of growth hormone secretion and body weight. Domestic Animal Endocrinology 5, 247255.
Bedos, M, Flores, JA, Fitz-Rodríguez, G, Keller, M, Malpaux, B, Poindron, P and Delgadillo, JA 2010. Four hours of daily contact with sexually active males is sufficient to induce fertile ovulation in anestrous goats. Hormones and Behavior 58, 473477.
Chemineau, P, Malpaux, B, Delgadillo, JA, Guérin, Y, Ravault, JP, Thimonier, J and Pelletier, J 1992. Control of sheep and goat reproduction: use of light and melatonin. Animal Reproduction Science 30, 157184.
Delgadillo, JA 2011. Environmental and social cues can be used in combination to develop sustainable breeding techniques for goat reproduction in the subtropics. Animal 5, 7481.
Delgadillo, JA, Canedo, GA, Chemineau, P, Guillaume, D and Malpaux, B 1999. Evidence for an annual reproductive rhythm independent of food availability in male creole goats in subtropical northern Mexico. Theriogenology 52, 727737.
Delgadillo, JA and Chemineau, P 1992. Abolition of the seasonal release of luteinizing hormone and testosterone in Alpine male goats (Capra hircus) by short photoperiodic cycles. Journal of Reproduction and Fertility 94, 4555.
Delgadillo, JA, Flores, JA, Véliz, FG, Hernández, HF, Duarte, G, Vielma, J, Poindron, P, Chemineau, P and Malpaux, B 2002. Induction of sexual activity in lactating anovulatory female goats using male goats treated only with artificially long. Journal of Animal Science 80, 27802786.
Delgadillo, JA, Leboeuf, B and Chemineau, P 1991. Decrease in the seasonality of sexual behavior and sperm production in bucks by exposure to short photoperiodic cycles. Theriogenology 36, 755770.
Delgadillo, JA, Leboeuf, B and Chemineau, P 1993. Maintenance of sperm production in bucks during a third year of short photoperiodic cyles. Reproduction Nutrition and Development 33, 609617.
Delgadillo, JA and Vélez, LI 2010. Stimulation of reproductive activity in anovulatory Alpine goats exposed to bucks treated only with artificially long days. Animal 4, 20122016.
Forbes, JM, Elshahat, AA, Jones, R, Duncan, JGS and Boaz, TG 1979. The effect of daylength on the growth of lambs. Animal Production 29, 3342.
Gettys, TW, Schanbacher, BD and Taylor, IL 1989. An assessement of the interaction between photoperiod and sex phenotype in relation to appetite development in the sheep. Livestock Production Science 2, 283293.
Hochereau-De Reviers, MT, Copin, M, Seck, M, Monet-Kuntz, C, Cornu, C, Fontaine, I, Perreau, C and Elsen, JM 1990. Stimulation of testosterone production by PMSG injection in the ovine male: effect of breed and age and application to males carrying or not carrying the “F” Booroola gene. Animal Reproduction Science 23, 2132.
Hötzel, MJ, Caraty, A and Martin, GB 1997. Effect of nutrition on testicular growth in mature Merinos rams actively immunized against GnRH. Journal of Reproduction and Fertility 110, 307313.
Leboeuf, B, Delgadillo, JA, Manfredi, E, Piacère, A, Clément, V, Martin, P, Pellicer, M, Boué, P and de Cremoux, R 2008. Management of goat reproduction and insemination for genetic improvement in France. Reproduction in Domestic Animals 43, 379385.
Lincoln, GA and Ebling, FJP 1985. Effect of constant-release implants of melatonin on seasonal cycles in reproduction, prolactin secretion and moulting in rams. Journal of Reproduction and Fertility 73, 241253.
Lincoln, GA and Short, RV 1980. Seasonal breeding: nature’s contraceptive. Recent Program Hormones and Research 36, 152.
Malpaux, B and Chesneau, D 2006. Maîtrise de la saisonnalité de la reproduction chez les ovins: un nouveau traitement photopériodique. Poster presented at Congrès de la Société Française de Chronobiologie, Lyon, 9–11 May, Lyon, France.
Malpaux, B, Robinson, JE, Wayne, NL and Karsch, FJ 1989. Regulation of the onset of the breeding season of the ewe: importance of long days and of endogenous reproductive rhythm. Journal of Endocrinology 122, 269278.
Oldham, CM, Adams, NR, Gherardi, PB, Lindsay, DR and McKintosh, JB 1978. The influence of level of feed intake on sperm-producing capacity of testicular tissue in the ram. Australian Journal of Agricultural Research 29, 173179.
Ortavant, R, Bocquier, F, Pelletier, J, Ravault, JP, Thimonier, J and Volland-Nail, P 1988. Seasonality of reproduction in sheep and its control by photoperiod. Australian Journal of Biological Science 41, 6985.
Pelletier, J and Almeida, G 1987. Short light cycles induce persistent reproductive activity in Ile-de-France rams. Journal of Reproduction and Fertility 34, 215226.
Pelletier, J and Ortavant, R 1975. Photoperiodic control of LH release in the ram. II. Light-androgens interaction. Acta Endocrinologica Copenhage 78, 442450.
Pellicer-Rubio, MT, Leboeuf, B, Bernelas, D, Forgerit, Y, Pougnard, JL, Bonné, JL, Senty, E, Breton, S, Brun, F and Chemineau, P 2008. High fertility using artificial insemination during deep anoestrus after induction and synchronisation of ovulatory activity by the “male effect” in lactating goats subjected to treatment with artificial long days and progestogens. Animal Reproduction Science 109, 172188.
Ponce, JL, Velázquez, H, Duarte, G, Bedos, M, Hernández, H, Keller, M, Chemineau, P and Delgadillo, JA 2014. Reducing exposure to long days from 75 to 30 days of extra-light treatment does not decrease the capacity of male goats to stimulate ovulatory activity in seasonally anovulatory females. Domestic Animal Endocrinology 48, 119125.
SAGARPA 2001. Norma Oficial Mexicana NOM-062-ZOO-1999. Especificaciones técnicas para la producción, cuidado y uso de los animales de laboratorio. Diario oficial de la federación, 22 de agosto, pp. 157.
Staples, LD, McPhee, S, Reeve, J and Williams, AH 1991. Practical applications for controlled release melatonin implants in sheep. In Advances in pineal research (ed. A Foldes and RJ Reiter), pp. 199208. John Libbey and Co., London.
Walkden-Brown, SW, Restall, BJ, Scaramuzzi, RJ, Martin, GB, Blackberry, MA 1997. Seasonality in male Australian cashmere goats: long term effects of castration and testosterone or oestradiol treatment on changes in LH, FSH and prolactin concentrations, and body growth. Small Ruminant Research 26, 239252.
Walkden-Brown, SW, Restall, JB, Norton, BW, Scaramuzzi, RJ and Martin, GB 1994. Effect of nutrition on seasonal pattern of LH, FSH and testosterone concentration, testicular mass, sebaceous gland volume and odour in Australian cashmere goats. Journal of Reproduction and Fertility 102, 351360.
Woodfill, CJI, Wayne, NL, Moenter, SM and Karsch, FJ 1994. Photoperiodic synchronization of a circannual reproductive rhythm in sheep: identification of season-specific time cues. Biology of Reproduction 50, 965976.
Zarazaga, LA, Gatica, MC, Celi, I, Guzmán, JL and Malpaux, B 2010. Effect of artificial long days and/or melatonin treatment on the sexual activity of Mediterranean bucks. Small Ruminant Research 93, 110118.



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