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The effect of melatonin implants administered from December until April, on plasma prolactin, triiodothyronine and thyroxine concentrations and on the timing of the spring moult in cashmere goats

Published online by Cambridge University Press:  02 September 2010

P. Dicks ,
A. J. F. Russel  and
G. A. Lincoln
P. Dicks
Affiliation:
Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB9 2QJ
A. J. F. Russel
Affiliation:
Macaulay Land Use Research Institute, Craigiebuckler, Aberdeen AB9 2QJ
G. A. Lincoln
Affiliation:
MRC Reproductive Biology Unit, 37 Chalmers Street, Edinburgh EH3 9EW
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Abstract

The effect of melatonin implants administered to cashmere goats in the winter, on plasma prolactin, triiodothyronine (T3) and thyroxine (T4) concentrations and the timing of the spring moult, was studied with the objective of identifying a method of manipulating the timing of the spring moult and increasing fibre harvesting efficiency. The effect of similar melatonin implants on prolactin concentration when administered in the increasing daylength of spring, was also measured.

In the first experiment, using 20 juvenile and 20 adult female cashmere goats, half the animals of each group received continuous release implants of melatonin (18 mg) on 11 December, 1 February and 1 April. In the adult goats the treatment significantly advanced by 7 weeks the time at which peak plasma prolactin concentrations were attained (P < 0·001) and advanced the onset (P < 0·001) of the peak. The treatment also resulted in an advance of the spring moult of cashmere in the adult goats (P < 0·01) and in an earlier initiation (P < 0·01) of the growth of both guard hair and cashmere as judged by histological examination of primary and secondary hair follicles. In the juvenile goats there were no significant effects of melatonin administration on plasma prolactin concentrations, the timing of the moult, or on any of the histological measurements compared with the controls. There were no significant effects on live weight or circulating concentrations of T3 and T4 in either age group. In the second experiment, the administration of one melatonin implant (18 mg) to three adult goats on 1 April caused a significant reduction in plasma prolactin concentrations (P < 0·05) over a period of 3 weeks compared with concentrations observed in four untreated goats.

It is concluded that treatment with melatonin implants is effective in modifying the timing of the seasonal cycle in prolactin secretion in adult cashmere goats and causing corresponding changes in hair follicle activity. However, since the treatment initiated in December caused an advance rather than a delay in the normal spring rise in plasma prolactin concentrations, it is evident that the repeated melatonin implant protocol used in this experiment cannot be used to delay the onset of the spring moult and thus facilitate the harvesting of cashmere.

Keywords

cashmeremelatoninprolactintriiodothyroninethyroxine
Type
Research Article
Information
Animal Science , Volume 60 , Issue 2 , April 1995 , pp. 239 - 247
Copyright
Copyright © British Society of Animal Science 1995

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References

Allain, D., Martinet, L. and Rougeot, J. 1981. Effect of melatonin implants on changes in the coat, plasma prolactin and testes cycle in the mink (Mustela vison). In Photoperiodism and reproduction in vertebrates (ed. Ortavant, R., Pelletier, J. and Ravault, J. P.), pp. 23–271. INRA Services Publications, Versailles.Google Scholar
Betteridge, K., Welch, R., Pomroy, W., Lapwood, K. and Devantier, B. 1987. Out of season cashmere growth in feral goats. Proceedings of the second international cashmere conference, New Zealand, pp. 137–143.Google Scholar
Chase, H. B. 1958. Physical factors which influence the growth of hair. In The biology of hair growth (ed. Montagna, W. and Ellis, R. A.), chapter 17. Academic Press, London.Google Scholar
Ferguson, K. A., Wallace, A. L. C. and Lindner, H. R. 1965. Hormonal control of wool growth. In Biology of the skin and hair growth (ed. Lyne, A. G. and Short, B. F.), pp. 655–677. Angus and Robertson, Sydney.Google Scholar
Hardy, M. H. and Lyne, A. G. 1956. The prenatal development of wool follicles in merino sheep. Australian Journal of Biological Sciences 9: 423–430.CrossRefGoogle Scholar
Johnson, E. 1977. Cycles and patterns of hair growth. In Physiology and pathophysiology of the skin. IV. The hair follicle (ed. Jarret, A.), pp. 1237–1249. Academic Press, London.Google Scholar
Kennaway, D. J., Gilmore, T. A. and Seamark, R. F. 1982a. Effect of melatonin implants on the circadian rhythm of plasma melatonin and prolactin in sheep. Endocrinology 110: 2186–2188.CrossRefGoogle ScholarPubMed
Kennaway, D. J., Gilmore, T. A. and Seamark, R. F. 1982b. Effects of melatonin feeding on serum prolactin and gonadotrophin levels on the onset of seasonal estrous cyclicity in sheep. Endocrinology 110: 1766–1772.CrossRefGoogle ScholarPubMed
Lincoln, G. A. 1990. Correlation with changes in horns and pelage, but not reproduction, of seasonal cycles in the secretion of prolactin in rams of wild, feral and domesticated breeds of sheep. Journal of Reproduction and Fertility 90: 285–296.CrossRefGoogle Scholar
Lincoln, G. A. and Ebling, F. J. P. 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: 241–253.CrossRefGoogle ScholarPubMed
Lyne, A. G. and Heideman, M. J. 1989. The prenatal development of skin and hair in cattle (Bos taurus L.). Australian journal of Biological Science 12: 72–80.CrossRefGoogle Scholar
McNeilly, A. S. and Andrews, P. 1974. Purification and characterisation of caprine prolactin. Journal of Endocrinology 115: 273–282.Google Scholar
Martinet, L. and Allain, D. 1985. Role of the pineal gland in the photoperiodic control of reproductive and nonreproductive functions in mink (Mustela vison). In Photoperiodism, melatonin and the pineal, Ciba Foundation symposium 117, pp. 170–187. Pitman, London.Google Scholar
Maywood, E. S., Grosse, J., Lindsay, J. O., Karp, J. D., Powers, J. B., Ebling, F. J. P., Herbert, J. and Hastings, M. H. 1992. The effect of signal frequency on the gonadal response of male Syrian hamsters to programmed melatonin infusions. Journal of Neuroendocrinology 4: 37–43.Google Scholar
Millar, P. 1986. The performance of cashmere goats. Animal Breeding Abstracts 54: 181–199.Google Scholar
Rose, J., Stormshak, F., Oldfield, J. and Adair, J. 1985. The effects of photoperiod and melatonin on serum prolactin levels of mink during the autumn moult. Journal of Pineal Research 2: 13–19.CrossRefGoogle Scholar
Ryder, M. L. 1966. Coat structure and seasonal shedding in goats. Animal Production 8: 289–302.Google Scholar
Ryder, M. L. 1973. The structure of, and growth cycles in, the cost of wild mouflon sheep (Ovis musimo) and their crosses. Research in Veterinary Science 15: 186–196.CrossRefGoogle Scholar
Scheurman, E., Staples, L., McPhee, S. and Galloway, D. 1987. The effect of exogenous melatonin on reproductive and fleece parameters when administered to Australian goats prior to the natural breeding season. Proceedings of the second international cashmere conference, New Zealand, pp. 145–157.Google Scholar
Seron-Ferre, M., Vergara, M., Parraguez, N. H., Riquelme, R. and Llanos, A. J. 1989. Fetal prolactin levels respond to a maternal melatonin implant. Endocrinology 125: 400–403.Google Scholar
Smith, A. J., Mondain-Monval, M., Berg, K. A., Simon, P., Forsber, M., Clausen, O. P. F., Hansen, T., Moller, O. M. and Scholler, R. 1987. Effects of melatonin implantation on spermatogenesis, the moulting cycle and plasma concentrations of melatonin, LH, prolactin and testosterone in the male blue fox (Alopex lagopus). Journal of Reproduction and Fertility 79: 379–390.Google Scholar
Spearman, R. I. C. 1977. Hair follicle development, cyclical changes and form. In The physiology and pathophysiology of the skin. Vol IV. The hair follicle (ed. Jarrett, A.). Academic Press, London.Google Scholar
Stetson, M. H., Elliott, J. A. and Goldman, B. D. 1986. Maternal transfer of photoperiodic information influences the photoperiodic response of prepubertal Djungarian hamsters (Phodopus sungorus sungorus). Biology of Reproduction 34: 664–669.Google Scholar
Straile, W. D., Chase, H. B. and Arsenault, C. 1961. Growth and differentiation of hair follicles between periods of activity and quiescence. Journal of Experimental Zoology 148: 205–221.CrossRefGoogle ScholarPubMed
Wainman, F. W., Smith, J. S. and Dewey, P. J. S. 1975. The nutritive value for sheep of ruminant diet AA6, a complete cobbed diet containing 30% barley straw. Journal of Agricultural Science, Cambridge 84: 109–112.CrossRefGoogle Scholar
Wallace, A. L. C. 1979a. The effects of hormones on wool growth. In Physiological and environmental limitations to wool growth (ed. Black, J. L. and Reis, P. J.). University of New England, NSW, Australia.Google Scholar
Wallace, A. L. C. 1979b. Variation in plasma thyroxine concentration throughout one year in penned sheep on a uniform intake. Australian Journal of Biological Science 32: 371–374.Google Scholar