Abstract
An increase in the negative feedback effects of oestradiol on tonic LH secretion, coinciding with the period of seasonal anoestrus, is thought to be casually related to the seasonal nature of breeding in the ewe. This results in a low frequency of episodic LH secretion, below that required to promote the final phases of follicle development and maturation which immediately preceed ovulation. Artificially increasing tonic LH secretion in seasonally anoestrous ewes, by administration of low doses of GnRH in the form of either pulsed injections or continuous infusion, will induce follicle development with an associated increase in oestradiol secretion sufficient to promote the positive feedback response and thereby induce ovulation. This occurs without the need for any GnRH-induced increase in FSH secretion. A high proportion of the induced corpora lutea are functionally abnormal unless the GnRH treatment is preceeded by a period of progesterone priming.
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© 1985 ECSC, EEC, EAEC, Brussels-Luxembourg
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Haresign, W., McLeod, B.J., Webster, G.M., Worthy, K. (1985). Endocrine Basis of Seasonal Anoestrus in Sheep. In: Ellendorff, F., Elsaesser, F. (eds) Endocrine Causes of Seasonal and Lactational Anestrus in Farm Animals. Current Topics in Veterinary Medicine and Animal Science, vol 31. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-5026-9_3
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DOI: https://doi.org/10.1007/978-94-009-5026-9_3
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