Measurement of total thyroxine levels in bovine, equine, ovine and porcine plasma : A thesis submitted in partial fulfilment of the requirements for the Degree of Master of Agricultural Science in the University of Canterbury

Abstract

In more recent years, studies have been orientated toward the physiological levels of thyroid hormones with the measurement of thyroxine secretion rate, thyroxine utilization rate and free plasma thyroxine. Calculation of these parameters of thyroid function requires an accurate measurement of total plasma thyroxine . It was with the realisation of the importance of accurate measurement of total plasma thyroxine that this study was initiated. The objectives of the study are two- fold: first, to isolate an accurate and reproducible method of assaying total thyroxine in bovine, equine, ovine and porcine plasma; and secondly, to use the method to measure any seasonal variation in the total plasma thyroxine level of the ewe and any age variation in the new born lamb during the first three weeks of postnatal life.