Effects of dietary Lactobacillus helveticus on the growth rate, disease resistance and intestinal health of pond loach (Misgurnus anguillicaudatus)

This study sought to investigate the effects of Lactobacillus helveticus HML037 dietary supplementation on the growth performance, innate immunity, disease resistance and intestinal health of the pond loach (Misgurnus anguillicaudatus). Three hundred and sixty loaches were randomly divided into four experimental diets supplemented with 0 (C group), 1 × 107 (T1 group), 1 × 108 (T2 group), and 1 × 109 (T3 group) CFU g−1 of L. helveticus HML037. After 8 weeks of feeding, the results demonstrated that the growth performance, digestive enzyme activity, the expression levels of immune-related genes and growth-related genes, antioxidant response, and disease resistance against pathogenic bacteria of M. anguillicaudatus were all significantly increased by the diets containing different levels of L. helveticus HML037 compared with the control group, specifically, the optimal dietary L. helveticus HML037 was 1 × 108 CFU g−1. Activation of immunity was consistent with the microbiota data showing that the species richness and diversity of the L. helveticus HML037 addition group were remarkably increased, and the abundance of Lactobacillus was increased, and the abundance of Aeromonas, Acidovorax and Shewanella were decreased. These results indicated that dietary L. helveticus HML037 supplementation could promote growth performance, non-specific immunity and the healthy gut microbiota of M. anguillicaudatus, and therefore may be implemented as an effective loach dietary supplement.