title: Serum calcium and phosphorus levels in hens relative to the time of oviposition.
abstract: An experiment was conducted to examine the serum calcium and phosphorus level of hens in relation to time of oviposition. Sixty-eight-week-old hens were selected for blood sampling according to the criteria that: 1. they laid an egg the day prior to and the day of blood collection, and 2. the oviposition time on both days was 10 a.m. +/- 2 hours. Samples were taken at hourly intervals, from five hours before through two hours after, and again at four hours after oviposition and were analyzed for serum calcium and phosphorus. All birds received natural and/or artificial light from 4:30 a.m. to 7:30 p.m. each day. Results indicated that serum phosphorus increased from 6.46 to 6.82 mg.% during the period from five to three hours prior to oviposition. Between three and two hours before time of lay, it dropped to a level of 4.75 mg.%, where it remained (+/- 0.35 mg.%) for the remainder of the test period. Serum calcium did not change appreciably during the 10-hour test period. It was hypothesized that the serum phosphorus cycle of the hens is composed of two segments of approximately six and 18 hours duration. The segments were delineated on the basis of activities of bone resoprtion and remineralization and egg shell formation.
mesh_terms: D000818:Animals; D002118:Calcium / Q000097:blood*; D002645:Chickens / Q000097:blood* / Q000502:physiology; D005260:Female; D010058:Oviposition; D010758:Phosphorus / Q000097:blood*; D013997:Time Factors
chemical_list: D010758:Phosphorus; D002118:Calcium