title: Effects of age on intestinal phosphate transport and biochemical values of broiler chickens.
abstract: OBJECTIVE
  The objective of this experiment was to characterize the mRNA expression profile of type IIb sodium-inorganic phosphate cotransporter (NaPi-IIb) and the biochemical values of serum alkaline phosphatase (AKP), calcium, inorganic phosphorus, tibial ash and minerals of broiler chickens with aging.
  
  
  METHODS
  A total of 56 one-day-old Arbor Acres male broiler chickens were used. Broiler chickens were weighed and samples were collected weekly from day 1.
  
  
  RESULTS
  The result showed that before the growth inflection point, ash, calcium, and phosphorus content in the tibia of broiler chickens increased with growth (before 3 weeks of age), although there were no significant differences in chicks at different ages in the later period of the experiment and weight gain rate was relatively slow at this stage (4 to 6 weeks). NaPi-IIb gene expression in the small intestine in the early growth stage was higher than that in the later growth stage. Expression of calbindin and the vitamin D receptor protein in the intestinal mucosa increased with age in the duodenum and jejunum. Serum AKP activity first increased and subsequently decreased after peaking at 1 week of age, but there was no significant difference after 3 weeks of age.
  
  
  CONCLUSIONS
  These results show that compared with the early growth stage, the weight-gain rate of broiler chickens in the late growth stage gradually decreased with gradual tibia maturation, along with weaker positive transport of phosphorus in the intestine and reinforced re-absorption of phosphorus in the kidney, which might be the reason that phosphorus requirement in the late growth stage was decreased.
authors.affiliation: College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi 030801, China.|State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Jianhui
authors.initials: J
authors.lastname: Li
authors.affiliation: State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Jianmin
authors.initials: J
authors.lastname: Yuan
authors.affiliation: College of Animal Science and Veterinary Medicine, Shanxi Agricultural University, Shanxi 030801, China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Miao
authors.affiliation: State Key Laboratory of Animal Nutrition, College of Animal Science and Technology, China Agricultural University, Beijing 100193, China.
authors.forename: Yuming
authors.initials: Y
authors.lastname: Guo
keywords: Biochemical Values; Broiler Chickens; Growth; Intestinal Transport; Phosphorus