| The experiment was to determine the effect of different zinc sources and levels on growth performance and relative bioavailability（RBV）in broiler chickens.720 1-d-old male Arbor Acres broiler chickens were allocated to 10 treatments for 6 replicates and 12birds per replicate.The dietary treatments were:（1）basal control diet（without supplemental Zn）;（2）basal diet+20,40 or 80 mg of Zn/kg from Zn SO4（SZM）;（3）basal diet+20,40 or 80 mg of Zn/kg from tetrabasic zinc chloride（TBZC）;（4）basal diet+20,40or 80 mg of Zn/kg from protein zinc（PRZ）.Birds were weighed on days 0,14,28 and 42for growth performance.On day 14 and 28,2 randomly selected birds per pen were used to collecte bilateral tibia bone,pancreas,and blood.Results showed that dietary supplement with zinc improved（P<0.05）average daily gain（ADG）and gain:feed（G:F）for day 1 to day 14.Zinc levels significantly increased plasma and tibia zinc content at day 14.Compared with SZM and PRZ,TBZC had higher acativity of alkaline phosphatase（ALP）in plasma of chickens at day 14.PRZ supplementation significantly increased plasma T-SOD and Cu Zn-SOD enzyme activities and pancreatic MT m RNA expression in14-day-old chickens.Using the slope ratio method of multivariate linear regression,SZM as the reference.The RBV of TBZC based on ADG,FCR and ALP in starter phase were110.82%,110.82%and 106.03%,respectively.The RBV of PRZ were 102.90%,113.38%and 109.64%,respectively.Based on T-SOD,Cu Zn-SOD,and pancreatic MT m RNA,the RBV of TBZC was 98.90%,111.58%and 107.87%,respectively,And the RBV of PRZ was 113.86%,96.56%and 130.56%,respectively.It was concluded that TBZC and PRZ had increased ADG and G:F at stater phase chicken and the RBV of TBZC and PRZ were98%to 110%. |
