A study of certain factors affecting reproduction in the mare

Abstract

This thesis describes a study of the behavioural, hormonal and ovarian changes recorded in groups of housed mares during late autumn / spring over three years. In the first year the investigations concerned larger mares but these were replaced by pony mares during the subsequent two years. In the third year, mares demonstrating positive oestrous behaviour were mated. Variations from normal cyclical activity are discussed. Incorporated in this study was an investigation into the effects of different environmental lighting on melatonin patterns and on reproductive activity in the pony mares. A radioimmunoassay for the estimation of plasma melatonin concentration was established and the assay validated by recognised reliability criteria. No correlation was found between environmental lighting, patterns of melatonin secretion and reproductive activity in these mares. Factors which may have affected reproductive activity in this study, other than light and plasma melatonin concentration, are suggested and discussed

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