Effect of zinc-bearing zeolite clinoptilolite on growth performance, zinc accumulation, and gene expression of zinc transporters in broilers.

Abstract

This study investigated Zn-bearing zeolite clinoptilolite (Zn-ZCP) as a Zn supplement on performance, organ or tissue development, Zn accumulation in tissues, and gene expression of Zn transporters in the duodenum of broilers. A total of 300 1-d-old Arbor Acres chickens were randomly allocated to 5 dietary treatments with 6 replicate cages of 10 birds per treatment for a 21-d feeding period. The treatments comprised a basal corn–soybean meal diet without supplemental Zn (the control) or similar diets supplemented with 80 mg/kg Zn from ZnSO4 or 20, 40, or 80 mg/kg Zn from Zn- ZCP, respectively. Supplementation of Zn-ZCP had a positive effect on G:F (linear, P < 0.05) and had tendency difference on ADG (linear, P < 0.1) of broilers during 1 to 21 d. Incremental Zn-ZCP inclusion in the diet increased the fresh weight of the pancreas (linear, P < 0.05) and tibia (linear, P < 0.05) in broilers on d 14. The same trend to the fresh weight of the tibia (linear, P < 0.05) and pancreas (linear, P < 0.05) was observed on d 21. Increasing Zn-ZCP level showed a linear response on Zn concentration in the liver (linear, P < 0.001), pancreas (linear, P < 0.05), and tibia (linear, P < 0.05) on d 14. The same trend of Zn concentrations in pancreas (linear, P < 0.05) and tibia (linear, P < 0.001) was observed on d 21. The mRNA levels of Zn transporter 2 (ZnT-2) and Zn transporter 5 (ZnT-5) in the duodenum of chicks fed the diet with 80 mg/kg Zn from Zn-ZCP did not differ from those of chicks fed the control diet, but both were lower (P < 0.05) than those of chicks fed ZnSO4 diet. Metallothionein (MT) mRNA levels of broilers fed the diet supplemented with 80 mg/kg Zn from Zn-ZCP or ZnSO4 was higher (P < 0.05) than that in the control group. Dietary treatments did not affect the mRNA expression of Zn transporter 1 (ZnT-1) or metal response element-binding transcription factor-1 (MTF-1). In conclusion, as a Zn supplement, Zn-ZCP was comparable to ZnSO4 for enhancing Zn accumulation and growth performance of broilers during 1 to 21 d. Broilers fed the diet with 80 mg/kg Zn from Zn-ZCP had different expressions of ZnT-2 and ZnT-5 in the duodenum compared with those fed the ZnSO4 diet.