Impacts of dietary supplementation of bamboo vinegar and charcoal powder on growth performance, intestinal morphology, and gut microflora of large-scale loach Paramisgurnus dabryanus

Although accumulating data demonstrate that dietary supplementation of bamboo vinegar and charcoal powder (BVC) can significantly strengthen the immunity and boost the growth of domestic animals, its application potency still awaits verification in commercial fish species such as the large-scale loach Paramisgurnus dabryanus. The impacts of 90-day dietary supplementation of 1% and 2% BVC on survival and growth performance of the loach, and on the intestinal morphological characteristics and gut microflora were analyzed. Our data show that the large-scale loach supplied with BVC at the experimental doses had significant higher survival rates and better growth performance (indicated by greater weight gain (1.13–1.14 times), higher specific growth rate (1.04 times), and lower feed conversion ratio (0.88–0.89 times)) compared to that of the control (P<0.05). Histological examination revealed significant longer villus (3.22–5.54 times), deeper crypt (1.77–1.87 times), and thicker muscle (1.59–3.17 times) in the intestines of large-scale loach fed with BVC (P<0.05). Furthermore, we found that the gut microflora consisted of significantly fewer proportions of potential pathogenic bacterial species (Aeromonas veronii and Escherichia coli), but significantly greater proportions of beneficial microbes (Lactococus raffinolactis and Faecalibacterium prausnitzii). Therefore, dietary intake of BVC can promote intestinal tract development and optimize gut microflora, by which the survival and growth of large-scale loach may be improved. ELECTRONIC SUPPLEMENTARY MATERIAL: Supplementary material (Supplementary Table S1) is available in the online version of this article at 10.1007/s00343-022-1412-y.