Effects of dietary fiber on fecal microbiota of grower-finisher pig offspring from parents with divergent estimated breeding value for feed conversion ratio

The study investigated how dietary fiber influences fecal microbiota in grower-finisher pigs, particularly in those genetically selected for feed efficiency based on estimated breeding value for feed conversion ratio (EBV_FCR). Pigs were fed either a high-fiber (HF, 5.62% crude fiber, dry matter basis, DM) or low-fiber (2.46% crude fiber, DM basis) diet throughout three feeding phases (25-50, 50-75, and 75-100 kg) over 70 days. Fresh fecal samples were manually collected at various stages of pig growth and analyzed using 16S rRNA gene sequencing. The results showed that Firmicutes and Bacteroidetes were the dominant phyla in pigs, irrespective of genetic background or diet. However, bacterial families and genera were differentially influenced by genetic factors (feed efficiency selection) and dietary fiber content. High-efficiency pigs had higher abundances of Desulfovibrionaceae, while low-efficiency pigs exhibited greater levels of Campylobacter. Overall, increased dietary fiber enhanced microbial richness and evenness, underscoring its role in shaping the pig gut microbiota. Butyrate-producing bacteria, including those from Ruminococcus, Lachnospira_1, and Fibrobacter_1, were significantly higher in pigs fed HF diets. The study highlighted the complex interactions between genetics, diet, and age in modulating microbiota composition.