Blend of natural and natural identical essential oil compounds as a strategy to improve the gut health of weaning pigs

•Replacing the pharmacological dose of ZnO via feeding strategies is priority in pig.•Blends of natural and natural identical essential oil is a potential strategy.•A mixture of cinnamaldehyde, cassia, aiowan and clove oil reduces the faecal Escherichia coli.•A mixture of cinnamaldehyde, cassia, aiowan and clove oil modifies the short-chain fatty acids in gut.•This outcome suggests the potential for improved piglets’ resilience and gut health. Weaning is one of the most critical phases in pig’s life, often leading to postweaning diarrhoea (PWD). Zinc oxide (ZnO), at pharmacological doses, has been largely used to prevent PWD; however, due to antimicrobial co-resistant and environmental pollution issues, the EU banned its use in June 2022. Natural or natural identical components of essential oils and their mixture with organic acids are possible alternatives studied for their antimicrobial, anti-inflammatory and antioxidant abilities. This study aimed to evaluate the effect of two blends of natural or natural identical components of essential oils and organic acids compared to ZnO on health, performance, and gut health of weaned pigs. At weaning (d0), 96 piglets (7 058 ± 895 g) were assigned to one of four treatments balanced for BW and litter: CO (control treatment), ZnO (2 400 mg/kg ZnO from d0 to d14); Blend1 (cinnamaldehyde, ajowan and clove essential oils, 1 500 mg/kg feed); Blend2 (cinnamaldehyde, eugenol and short- and medium-chain fatty acids, 2 000 mg/kg feed). Pigs were weighed weekly until d35. Faeces were collected at d13 and d35 for microbiota (v3–v4 regions of the 16 s rRNA gene) and Escherichia coli (E. coli) count analysis. At d14 and d35, eight pigs/treatment were slaughtered; pH was recorded on intestinal contents and jejunal samples were collected for morphological and gene expression analysis. From d7–d14, the Blend2 had a lower average daily gain (ADG) than CO and ZnO (P