Dietary supplementation of montmorillonite promotes growth and intestinal health in turbot (Scophthalmus maximus)

Montmorillonite (MMT), an aluminosilicate clay, has specific physical-chemical properties such as high surface area, strong absorptive power and high structural stability, these characteristics make the clay minerals as a beneficial feed additive in aquaculture. An 8-week study was carried out to evaluate the influence of dietary MMT on growth performance, hematological parameters, intestinal morphology and microbiota in juvenile turbot (35.37 ± 0.05 g). Fish were fed with four experimental diets encompassed MMT at levels of 0 (control group), 0.3%, 1.0% and 3.0% (named as MMT0, MMT0.3, MMT1.0 and MMT3.0, respectively). The results indicated that fish fed 0.3% MMT supplemented diet had significantly higher final body weight, weight gain rate, feed efficiency, serum alanine transaminase (ALT), superoxide dismutase (SOD) compared with fish fed control diet. Meanwhile, dietary 0.3% MMT inclusion significantly decreased serum malonaldehyde (MDA) compared with the control group. MMT administration at 0.3% significantly enhanced lipase activity and intestinal morphology (intestinal fold length and wall thickness) in turbot in comparison to control group. Intestinal bacteria, indicated by observed species, Shannon index and ACE index, was more diverse in the MMT1.0 treatment compared to the control group. Acidobacteria was more abundant in the MMT1.0 treatment compared to that in control treatment. In summary, the results of this study suggest that dietary supplementation of MMT at 0.3%−1.0% improved growth performance, intestinal morphology and modulate intestinal microbiota through increasing α-diversity in turbot.