title: Diurnal variation in circulating levels of free fatty acids and growth hormone during crop gland activity in the pigeon (Columba livia).
abstract: 1. Circulating levels of free fatty acids (FFA) and growth hormone (GH) were measured over a 24 hr period during the crop gland cycle of domestic pigeons (Columba livia). 2. Plasma FFA levels showed a marked circadian rhythm (p less than 0.004) with the peak level (considerably higher than that previously reported in nonbreeding pigeons) occurring at approximately 2400 hr. 3. It is suggested that these elevated levels reflect the increased demands for energy during incubation and crop "curd" production. 4. Diurnal fluctuations of plasma GH synchronizing with those of plasma FFA were not significant though peak concentrations were noted 4 hr previous to those of FFA. 5. Pigeons studied 12 days after hatching of young had the lowest levels of both plasma GH (p less than 0.06) and FFA (p less than 0.02) indicating their interacting relationship. 6. A consistently higher FFA level (p less than 0.02) was observed in the crop glands of male pigeons.
mesh_terms: D000818:Animals; D002940:Circadian Rhythm; D010856:Columbidae / Q000502:physiology*; D003426:Crop, Avian / Q000502:physiology*; D005230:Fatty Acids, Nonesterified / Q000378:metabolism*; D005260:Female; D013006:Growth Hormone / Q000378:metabolism*; D008297:Male; D012737:Sex Factors
chemical_list: D005230:Fatty Acids, Nonesterified; D013006:Growth Hormone