Effects of early sub-therapeutic antibiotic administration on body tissue deposition and the associated alternations on the gut microbiota and metabolite profiles of piglets

This study aims to evaluate the effects of sub-therapeutic antibiotic (STA) administration and its subsequent withdrawal on body tissue deposition, gut microbiota and metabolite profiles of piglets. The STA piglets were fed with STA (30 mg kg bacitracin methylene disalicylate, 75 mg kg chlortetracycline, 300 mg kg calcium oxytetracycline) for 14d and the target BW of the withdrawal period is 25 kg. The results showed that STA did not improve piglets' growth performance during the two periods. Piglets treated with STA had lower body water deposition during the withdrawal period and tended to increase body lipid deposition during the withdrawal period and the whole period than CON group. It was found that STA markedly altered the colonic microbiota and their metabolites of piglets. STA was initially effective in decreasing the abundance of pathogenic bacteria during the administration period; however, STA could not continue the effect during the withdrawal period, leading to the rebound of pathogenic bacteria such as Alloprevotella and the increased abundance of other pathogenic bacteria like Oscillibacter. Remarkably, STA treatment decreased Blautia abundance which plays a potential protective role against obesity either during the two periods. Metabolomic analysis indicated that STA mainly altered amino acid metabolism, lipid metabolism, and carbohydrate metabolism during the two periods. Furthermore, Spearman's correlation analysis showed that the gut microbiota was highly correlated with microbial metabolites changes. These results suggest that early STA administration may alter body tissue deposition later in life through reshaping the gut microbiota and their metabolite profiles. This article is protected by copyright. All rights reserved.