Effects of zinc-bearing clinoptilolite on growth performance, cecal microflora and intestinal mucosal function of broiler chickens

This study was conducted to evaluate the effect of zinc-bearing clinoptilolite (ZnCP) addition on growth performance, cecal microflora, intestinal antioxidant function and status, immune function of broiler chickens. A total of 300 one-day-old Arbor Acres chickens were randomly divided into 5 groups with 6 replicates of 10 birds each for a 42-day feeding trial. The dietary treatments were as follows: (1) control (CON) fed a basal diet; (2) the basal diet plus antibiotic (40 mg chlortetracycline per kg of diet, ANT); (3) the basal diet plus 0.1% ZnCP; (4) the basal diet plus 0.2% ZnCP; (5) the basal diet plus 0.4% ZnCP. ZnCP treatments had positive effect on average daily gain (ADG) (linear, P = 0.005; quadratic, P = 0.093) of broilers during 1–21 days. The population of Escherichia coli in cecal content decreased linearly (P = 0.048) and quadratically (P = 0.045) on day 21 and day 42 (linear, P = 0.032; quadratic, P = 0.081) with increasing ZnCP levels. The activities of total superoxide dismutase (T-SOD) (linear, P = 0.001) and Cu–Zn superoxide dismutase (Cu–Zn SOD) (linear, P < 0.001) in jejunal mucosa were increased by supplementary ZnCP at 21 day. Malondialdehyde (MDA) contents in jejunum (linear, P = 0.001; quadratic, P = 0.008) and ileum (linear, P = 0.018; quadratic, P = 0.012) were reduced by ZnCP treatments at 21 day. GSH content in jejunum was significantly increased at 21 day (linear, P < 0.001; quadratic, P = 0.009) by ZnCP treatments. Compared to CON and ANT, 0.2% and 0.4%ZnCP treatments significantly increased immunoglobulin G (IgG) in jejunal mucosa at 21 day (P < 0.05), and 0.1% ZnCP supplementation improved the content of secretory immunoglobulin A (sIgA) in jejunum at 42 day (P < 0.05). The results suggested that supplementation with 0.1% or 0.2% ZnCP modulated microbial populations and improved immune function and antioxidant status in the gastrointestinal (GI) tract, which may exert protective effects on the integrity of the mucosal barrier function of broilers, was as efficacious as 40 mg chlortetracycline per kg in enhancing growth performance. The results indicated that ZnCP may be used as a new growth promoter instead of antibiotics in poultry feed.