Bioavailability evaluation of zinc-bearing palygorskite as a zinc source for broiler chickens

The aim of the present study was to evaluate the bioavailability of zinc-bearing palygorskite (Zn-Pal) in broilers. A total of 432 one-day-old Arbor Acres broilers were randomly assigned to nine groups administered different dietary treatments for 42 days. The broilers were fed a basal diet supplemented with 0, 20, 40, 60 or 80 mg/kg of Zn in the form of either feed-grade ZnSO4 or Zn-Pal, respectively. The growth performance was not affected by the addition of Zn (P > 0.05). At 21 days of age, the content of Zn in the blood of broilers fed diets supplemented with Zn-Pal was higher than that of broilers fed diets supplemented with ZnSO4 (P < 0.01). A dose-dependent response was observed between the supplemental Zn level and the Zn content in the tibia in both the starter (1-21 days) and grower periods (22-42 days, P < 0.01). The maximal Zn content was observed in the pancreas and tibia of broilers fed 80 mg/kg of Zn as ZnSO4 or 60 mg/kg of Zn as Zn-Pal. The broilers fed 80 mg/kg of Zn as either ZnSO4 or Zn-Pal had the highest Zn content in the breast muscle (P < 0.05). At 42 days of age, the contents of Zn in the pancreas, tibia and breast muscle increased with supplemental Zn levels (P < 0.01). Zn-Pal increased the Zn content in the tibia compared with ZnSO4 (P < 0.05). At 21 days of age, the relative biological values (RBVs) of Zn-Pal were 109.64%, 100% and 100%, as determined using the contents of Zn in the pancreas, tibia and breast muscle, respectively, as response parameters. At 42 days of age, the RBVs of Zn-Pal were 86.32% and 119.55% based on the contents of Zn in the pancreas and tibia. It was concluded that Zn-Pal had a higher bioavailability than ZnSO4 in broiler diets. The optimal level of supplemented Zn for broilers was 60 mg/kg in the form of Zn-Pal. (C) 2015 Elsevier B.V. All rights reserved.