Short- and medium-chain fatty acids and chestnut tannin extract blend as supplement in poultry feeding: effect on animal performances and gut microbiota communities

Intensive poultry rearing needs preventive strategies against diseases, several of which are little or not containable by vaccinations. Short- and medium-chain fatty acids (SMCFAs) and chestnut tannin (CHT), both by-products of two different industrial production chains, are very effective antimicrobials. The inclusion level of these additives in the diet is fundamental because a detrimental effect on the gut microbiome can occur if the dose is too high, compromising the animal welfare and performance. Hence, the aim of this trial was to test the effect of a blend (BL; 1:1, w/w) of SMCFAs (fatty acids from C4:0 to C9:0) and CHT extract (CTE) as feed additive in broiler feeding. One hundred one-day-old Ross 308 male chicks were randomly assigned to 5 dietary treatments (4 replicates; 20 pens; 5 animals per pen): control diet (CON), FAS diet (with 1.5 g/100g on dry matter (DM) of SMCFAs), CTE diet (with 1.5 g/100g on DM of CHT extract), BL1 diet (with 1.5 g/100g on DM of BL), and BL2 diet (with 3.0 g/100g on DM of BL). Among the parameters evaluated (weight gain; feed intake; feed efficiency; dressing out), the only differences were observed for the feed intake. In particular, the feed intake of CON (2.876 kg), FAS (2.773 kg), CTE (2.882 kg), and BL1 (2.858 kg) were comparable while the feed intake of BL2 (2.717 kg) was lower than the other diets except for FAS which was similar (p = 0.0010). The microbial community in the caecum was described by high-throughput sequencing of 16S rRNA gene amplicons and was similar between the treatments both in terms of alpha-diversity and beta-diversity. The results of this trial evidenced that no detrimental effect on growth performances or on gut microbiome occurred when birds were fed the blend of SMCFAs and CHT extracts at the inclusion levels tested in this study.HIGHLIGHTSShort- and medium-chain fatty acids and chestnut tannins are alternatives to conventional antimicrobialsNatural antimicrobials improve the sustainability of poultry productionShort- and medium-chain fatty acids and chestnut tannins did not alter the gut microbiota of broiler