A COMPARISON OF PLASMA PROGESTERONE AND LUTEINIZING HORMONE IN GROWING HENS FROM EIGHT WEEKS OF AGE TO SEXUAL MATURITY

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Abstract
Agricultural Research Council's Poultry Research Centre, King's Buildings, West Mains Road, Edinburgh, EH9 3JS (Received 20 June 1977) In the maturing hen the concentration of luteinizing hormone (LH) in the plasma rises to a prepubertal maximum and then declines over a 2–3 week period until the first egg is laid (Sharp, 1975). Sharp (1975) postulated that increased secretion of progesterone by the developing ovary may be responsible for this fall in the level of LH since the large, yolky follicles, which are thought to be steroidogenic (Furr, 1969), develop over a 2–3 week period before the onset of lay (Wilson & Sharp, 1975). The present experiment was designed to test this hypothesis by direct measurement of the amount of progesterone and LH in the blood of growing hens. Variations in the level of LH in the peripheral plasma were determined by an homologous radioimmunoassay for avian LH (Follett, Scanes &