title: Luteinizing hormone concentrations in the plasma of laying hens exposed to a 27-hr cycle of light and darkness.
abstract: The time of peak concentration of LH in the peripheral plasma of ten laying hens kept on a 14 hr light/13 hr dark cycle was determined by radioimmunoassay. A single peak of LH occurred in each hen 3 1/2 hr before oviposition or 4 hr before ovulation. These are similar intervals to those reported for laying hens kept on a 14 hr light/10 hr dark cycle. The mean time of the observed peak in plasma LH was 2 hr 9 min after the beginning of the dark period. This is about 3 hr earlier than corresponding LH peaks reported for hens under normal lighting.
mesh_terms: D000818:Animals; D002645:Chickens / Q000502:physiology*; D002940:Circadian Rhythm; D003624:Darkness; D005260:Female; D008027:Light; D007986:Luteinizing Hormone / Q000097:blood*; D010058:Oviposition; D010060:Ovulation; D013997:Time Factors
chemical_list: D007986:Luteinizing Hormone