Effects of betaine on growth performance and colonic microbiota in weaned piglets

This study investigated the effects of dietary betaine supplementation on growth performance, diarrhea incidence, and the colonic microbiota of weaned piglets. A total of newly weaned 150 Duroc × Landrace × Yorkshire piglets were randomly assigned to three dietary treatments: a control diet or diets supplemented with 1,250 or 2,500 mg/kg betaine. Growth performance and diarrhea incidence were evaluated, and colonic microbial composition was analyzed by 16S rRNA gene sequencing. The functional potential of the microbiota was further predicted using PICRUSt2 and Tax4Fun2. The results showed that, compared with the control group, both betaine-supplemented groups significantly increased average daily gain (ADG) and reduced feed conversion ratio (FCR) and diarrhea incidence ( p < 0.05). Exploratory random forest analysis identified several candidate genera contributing to group discrimination, including Prevotellaceae_NK3B31_group , Oscillibacter , Oscillospira , and Ruminococcus_torques_group . Specifically, low-dose betaine supplementation altered the relative abundances of several genera, including Prevotellaceae_NK3B31_group , Oscillibacter , Oscillospira , and Ruminococcus_torques_group . Functional prediction further suggested that low-dose betaine was associated with enrichment of predicted KEGG pathways related to energy metabolism, including the citrate cycle (TCA cycle) (ko00020), butanoate metabolism (ko00650), and folate biosynthesis (ko00790). Overall, dietary betaine supplementation improved growth performance and reduced diarrhea incidence in weaned piglets. These phenotypic improvements were accompanied by changes in selected colonic bacterial taxa and predicted microbial functions. However, because microbial metabolites, SCFAs, intestinal barrier function, and immune indicators were not directly measured, the microbiota-related findings should be interpreted as associative and require further validation.