The effects of drinking water with essential oils-organic acids blend replacing preventive antibiotics during withdrawal period on growth performance and gut health of broilers in a commercial farm.

The maintenance of intestinal health is crucial for broilers during the withdrawal period. Substantial evidences have indicated that essential oil-organic acid complexes (EOAs) are effective in preserving poultry gut health. However, few studies were conducted to assess the effects of EOAs on production performance and gut health of broiler chickens in large-scale commercial broilers farms. The current study evaluated 0.15% EOA in drinking water as an alternative to preventive antibiotics in broilers before and during the mandatory withdrawal period (d 31-42) in a large-scale commercial broilers farm (16 rooms were randomly assigned to two equal groups with 8 rooms each group and 30,000 birds per room per replicate. The ANT group received neomycin sulfate in drinking water only pre-withdrawal (d 28-30), whereas the EOA group received 0.15% EOA from d 28 to 42, covering the entire withdrawal period. The results indicated that adding the essential oil-organic acid complex to drinking water during the withdrawal period significantly improved intestinal morphology by increasing the ratio of villus height to crypt depth (VH/CD) of jejunum and ileum (P < 0.05), increased Lactobacilli but decreased Escherichia coli and Salmonella population, lifted the activity of duodenal α-amylase and trypsin (P < 0.05), significantly downregulated tumor necrosis factor-α (TNF-α) mRNA levels and LPS content in the ileum and optimized intestinal microbial communities through enriching beneficial bacteria such as g_Ligilactobacillus, s Lactobacillus aviarius, s Ligilactobacillus salivarius, s Lactobacillus johnsonii, g_Pediococcus, and s Pedidcoccus pentosaceus in the cecum which were positively related with gut health biomarkers (P < 0.05) compared with the ANT group. While during the withdrawal phase ANT treatment notably increased Enterococcus cecorum, Burkholderia cepacia, Desulfovibrio relative abundance (P < 0.05) which were positively correlated with gut injury index. Thus, our findings indicated that EOA could be used as an effective alternative to preventive antibiotics to improve growth performance and maintain gut health during the drug-free period.