Dietary palygorskite-based antibacterial agent supplementation as an alternative to antibiotic improves growth performance, intestinal mucosal barrier function, and immunity in broiler chickens

The aim of this study was to evaluate effects of palygorskite-based antibacterial agent (PAA) as an alternative to antibiotic on growth performance, intestinal barrier function, and immunity in broilers. Three hundred and eighty-four mixed-sex 1-day-old Ross 308 broiler chicks were allocated into 6 groups of 8 replicates with 8 birds each. Birds were given a basal diet, an antibiotic diet (50 mg/kg chlortetracycline), and the basal diet supplemented with 250, 500, 1,000, and 2,000 mg/kg PAA for 42 d, respectively. Compared with control group, supplementing 1,000 mg/kg PAA reduced overall feed conversion ratio (P < 0.05), with its value being similar to that of antibiotic group (P > 0.05). However, a higher level of PAA (2,000 mg/kg) increased feed conversion ratio during the late period (P < 0.05). The 1,000 and 2,000 mg/kg PAA decreased plasma endotoxin and D-lactate levels at 42 d (P < 0.05) to comparable values (P > 0.05). The 1,000 mg/kg PAA decreased jejunal crypt depth, while 500 and 1,000 mg/kg PAA increased the ratio between jejunal villus height and crypt depth at 42 d (P < 0.05), with their values being similar to antibiotic group (P > 0.05). The highest level of PAA increased 42-d jejunal mucosal secretory immunoglobulin A and immunoglobulin M concentrations (P < 0.05). The 1,000 and 2,000 mg/kg PAA reduced 21-d interleukin-1β and tumor necrosis factor-α (TNF-α) levels in serum and ileal mucosa and 42-d interferon-γ level in serum and jejunal mucosa (P < 0.05), which did not differ from antibiotic group (P > 0.05). Moreover, PAA administration, regardless of its dosage, reduced 42-d serum TNF-α concentration, and 500 to 2,000 mg/kg PAA decreased 21-d and 42-d jejunal and 42-d ileal mucosal TNF-α levels (P < 0.05), with their values being comparable with antibiotic group (P > 0.05). The results suggested that PAA as an alternative to antibiotic could improve growth performance, intestinal barrier function, and immunity of broilers, and its optimal dosage was 1,000 mg/kg.