title: Metabolism and requirements for calcium and phosphorus in the fast-growing chicken as affected by age.
abstract: Three series of experiments were conducted with fast-growing chickens in order: to evaluate the effects of dietary Ca and P on cholecalciferol metabolism and expression; to determine dietary Ca requirements; to determine dietary P requirements. The results of the first series confirmed previous results on the effects of dietary Ca and P on some variables of vitamin D metabolism and expression, Ca homeostasis and P metabolism in the young chicken (1- to 21-d-old), and extended them to older birds (22- to 43-d-old). The bone formation rate and the duodenal calbindin content were maintained at high levels until the age of 43 d. Dietary Ca or P restriction increased duodenal calbindin and decreased bone ash in both 22- and 43-d-old chickens, but the effect on bone ash was less pronounced in the 43-d-old birds than in the younger ones. These results suggest that: (a) the capabilities for adaptation to dietary Ca and P restriction remain high during the whole growing period; (b) the growing broilers express a high adaptive capability even when the diet contains the recommended Ca and P contents. The results of the second and third series of experiments suggest that: (c) unlike the Ca requirements of the 1- to 22-d-old chick, P requirements for growth and bone ash are similar, and are as high in the older chicks as in the younger ones (7.4-8.3 g P/kg or 4.8-5.7 g non-phytate P/kg diet); (d) although growth and bone ash in the 29- to 43-d-old chickens appear to be less sensitive to dietary Ca content, within a range close to the calculated P requirement, 10 g Ca/kg diet appears to be required for best tibia mineralization, and to a lesser extent for better growth at this age.
authors.affiliation: Institute of Animal Science, Agricultural Research Organization, the Volcani Center, Bet Dagan, Israel. ariebar@agri.gov.il
authors.forename: Arie
authors.initials: A
authors.lastname: Bar
authors.forename: Dmitry
authors.initials: D
authors.lastname: Shinder
authors.forename: Sara
authors.initials: S
authors.lastname: Yosefi
authors.forename: Eliaho
authors.initials: E
authors.lastname: Vax
authors.forename: Isaac
authors.initials: I
authors.lastname: Plavnik
mesh_terms: D000375:Aging / Q000502:physiology*; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D001842:Bone and Bones / Q000378:metabolism; D064026:Calbindins; D002118:Calcium / Q000097:blood; D002136:Calcium, Dietary / Q000008:administration & dosage* / Q000378:metabolism; D002645:Chickens / Q000254:growth & development / Q000378:metabolism*; D002762:Cholecalciferol / Q000378:metabolism; D004032:Diet; D004386:Duodenum / Q000378:metabolism; D005260:Female; D008297:Male; D010758:Phosphorus / Q000097:blood; D016226:Phosphorus, Dietary / Q000008:administration & dosage* / Q000378:metabolism; D064030:S100 Calcium Binding Protein G / Q000378:metabolism; D015430:Weight Gain / Q000187:drug effects
chemical_list: D064026:Calbindins; D002136:Calcium, Dietary; D016226:Phosphorus, Dietary; D064030:S100 Calcium Binding Protein G; D002762:Cholecalciferol; D010758:Phosphorus; D002118:Calcium