title: Blood ionized calcium cycles in the chicken.
abstract: Changes in blood ionized calcium concentration (Ca++) appear to be dependent on the physiological state of the chicken. In the laying hen, blood Ca++ levels were affected by the ovulatory cycle; Ca++ was elevated when the shell gland was empty, declined following entry of an egg into that organ, and reached a minimum level approximately 16 hr prior to the subsequent oviposition. Pullets not in laying condition had blood Ca++ that varied with the photoperiod and/or rate of feed intake. In those pullets, blood Ca++ levels were depressed during the 9.5 hr of light, then rose in plateaued during the dark period. These studies indicate that blood Ca++ in laying hens is affected by the reproductive state first and the photoperiod and/or pattern of feed intake second.
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood*; D002645:Chickens / Q000097:blood* / Q000502:physiology; D005260:Female; D007477:Ions; D010058:Oviposition; D010758:Phosphorus / Q000097:blood; D011247:Pregnancy; D011270:Pregnancy, Animal
chemical_list: D007477:Ions; D010758:Phosphorus; D002118:Calcium