title: Effect of a microbial phytase on growth performance, plasma parameters and apparent ileal amino acid digestibility in Youxian Sheldrake fed a low-phosphorus corn-soybean diet.
abstract: OBJECTIVE
  This study investigated the effect of microbial phytase supplementation on growth performance, tibia ash, plasma parameters, apparent ileal digestibility (AID) of amino acid (AA) and apparent digestibility of nutrients in Youxian Sheldrakes fed with low-phosphorus (P) corn-soybean diets.
  
  
  METHODS
  A total of 350 Youxian Sheldrakes (7d old) were randomly divided into 5 treatment groups: positive control (PC) group has adequate available P diet (0.42% and 0.38%, starter and grower), negative control (NC) group were deficient in available P (0.32% and 0.28%, starter and grower) and NC diet was supplemented with 3 levels of microbial phytase (500, 750, and 1,000 U/kg).
  
  
  RESULTS
  Dietary supplementation of phytase in NC diet improved the average daily gain, increased the levels of serum calcium (Ca), tibia Ca and P, AID of AA and apparent digestibility of energy and Ca in starter stage (p<0.05). There was an increased (p<0.001) in the utilization of P from 17.3% to 23.9%. Phytase supplementation (1,000 U/kg) has shown that the AID of His, Thr, Val, indispensable AA, Glu, Pro, and dispensable AA was higher (p<0.05) than that of NC. Moreover, phytase supplementation improved (p<0.05) serum and tibia Ca and P, AID of AA and apparent digestibility of dry matter, crude protein, energy, P and Ca, and reduced (p<0.05) feed to gain ratio (F/G) and the levels of serum alkaline phosphatase in grower stage. Likewise, an increase (p<0.001) in the utilization of P was noticed from 12.6% to 17.2%. Supplement phytase at 750 U/kg improved the AID of His, Thr, Asp, Cys, Pro, and Ser (p<0.05).
  
  
  CONCLUSIONS
  The microbial phytase supplement could improve growth performance, AID of some AA and apparent utilization of other nutrients in Youxian Sheldrakes, and reduce excreta P load to environment.
authors.affiliation: College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China.
authors.forename: Shaoping
authors.initials: S
authors.lastname: He
authors.affiliation: College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China.
authors.forename: R F
authors.initials: RF
authors.lastname: Medrano
authors.affiliation: College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China.
authors.forename: Qifang
authors.initials: Q
authors.lastname: Yu
authors.affiliation: College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China.
authors.forename: Yixin
authors.initials: Y
authors.lastname: Cai
authors.affiliation: Department of Animal Nutrition and Feed Technology, Animal Husbandry and Veterinary Institute of Hunan Province, Changsha 410131, China.
authors.forename: Qiuzhong
authors.initials: Q
authors.lastname: Dai
authors.affiliation: College of Animal Science and Technology, Hunan Agricultural University, Changsha 410128, China.
authors.forename: Jianhua
authors.initials: J
authors.lastname: He
keywords: Apparent Ileal Amino Acid; Apparent Nutrient Digestibility; Performance; Phytase; Youxian Sheldrake