Effect of dietary supplementation Ampelopsis grossedentata extract on growth performance and muscle nutrition of Megalobrama hoffmanni by gut bacterial mediation

Abstract

Nowadays, Megalobrama hoffmanni is a typical cultured fish in south China due to its resource decline in the Pearl River. Meanwhile, since antibiotics had been banned internationally, Chinese medical herbal plant serving as alternative to antibiotics has been adopted in aquaculture. In the present study, to ensure the health growth of M. hoffmanni, extract of traditional medical herbal plant Ampelopsis grossedentata was dietary supplemented and a series experiments were performed, including growth performance determination, physiological/biochemical detection, nutrition analysis, histology analysis, and 16S rRNA amplicon sequencing. Growth performance enhancement was determined since the weight gain rate (WGR), specific growth rate (SGR), and condition factor (CF) of M. hoffmanni increased as feeding inclusion A. grossedentata extract. Interestingly, the total content of muscle fatty acids ascended via supplementing A. grossedentata extract at middle level, in which group the activities of superoxide dismutase (SOD) and catalase (CAT) significantly increased and thus retarded the lipid peroxidation process (manifesting as malondialdehyde (MDA) content rising). Additionally, immune response and inflammatory reaction was stimulated in low and high level A. grossedentata extract added groups, indicating a suitable dosage of A. grossedentata extract benefited in safety production. Moreover, gut microbiota community varied hugely as daily supplementation A. grossedentata extract and the keystone species were tightly related to lipid transformation, which ultimately led to fatty acids composition variation. Our results confirmed that dietary supplementation A. grossedentata extract at the middle level (0.5‰, w/w) is suitable for serving as feed additive in healthful aquaculture of M. hoffmanni.

Keywords: Ampelopsis grossedentata extract; Fatty acids; Growth performance; Gut microbiota; Megalobrama hoffmanni.

Fig. 1

Variation in morphological indices of Megalobrama hoffmanni. WGR is weight gain rate; SGR is specific growth rate; CF is condition factor; HSI is hepatopancreas somatic indices; VSI is visceral somatic indices. Different small letters indicate significant differences at p < 0.05 level under different treatments.

Fig. 2

Antioxidant enzymes (SOD and CAT) and component (MDA) of gill, liver, gut, and muscle in Megalobrama hoffmanni of the four tested groups. Different small letters indicate significant differences at p < 0.05 level under different treatments.

Fig. 3

Immunoglobulins (IgM, IgG, and IgA) and interleukins (IL-1β, IL-2, IL-4, IL-6, IL-10, and IL-12) in Megalobrama hoffmanni of the four tested groups. Different small letters indicate significant differences at p < 0.05 level under different treatments.

Fig. 4

Histological sections of gill ( × 200), liver ( × 400), gut ( × 400), and muscles ( × 100) tissues in Megalobrama hoffmanni of the four tested groups (A, B, C, and D).

Fig. 5

Variations in gut microbiota of the four tested groups. (A)–(C), alpha diversity. (A), Chao 1; (B) Simpson; (C), Shannon. (D), PCoA coupled with PERMANOVA revealed the beta diversity between groups. (E), top 10 abundant bacterial taxa at the class level. (F), heatmap showing the relative abundance of top 25 genera of bacteria. (G), random forest analysis coupled with ten-fold cross validation revealed the potential keystone taxa after treatment. (H), ternary diagram showing the Spearman's correlations between keystone taxa abundance and functional profiles imputed by PICRUSt2 involved in lipid and amino acid metabolism. (I), Sankey plot showing the relationship between keystone bacterial taxa, imputed functional profiles in gut, and nutrient content in muscle. Only the Spearman's correlation of coefficient r > 0.3 and p < 0.05 was visualized. The lines in red indicate the positive relationship whereas those in blue mean the negative relationship. Note: Different letters in histogram for alpha diversity indicate the significance between groups under non-parametric Kruskal-Walli's test under Dunn's multiple comparisons correction. Significance of keystone taxa abundance between groups were measured by nonparametric t-test under least significant difference (LSD) corrections. Abbreviations: V55, Propionibacteriaceae; V35, Microbacterium; V64, Actinomycetales; V264, Rhodobacter; V118, Chlamydiia; V213, Gemmataceae; V256, Rhizobiales; V11, Demequina; V7, Acidimicrobiales; V361, CK-1C4-19; V356, TM7-1. ko00061, fatty acid biosynthesis; ko00071, fatty acid degradation; ko00100, steroid biosynthesis; ko00120, primary bile acid biosynthesis; ko00121, secondary bile acid biosynthesis; ko00140, steroid hormone biosynthesis; ko00250, alanine, asparate and glutamate metabolism; ko00260, glycine, serine and threonine metabolism; ko00270, cysteine and methionine metabolism; ko00280, ko00281, general degradation; valine, leucine and isoleucine degradation; ko00290, valine, leucine and isoleucine biosynthesis; ko00300, lysine biosynthesis; ko00310, lysine degradation; ko00330, arginine and proline metabolism; ko00340, histidine metabolism; ko00350, tyrosine metabolism; ko00360, phenylalanine metabolism; ko00380, tryptophan metabolism; ko00400, phenylalanine, tyrosine and tryptophan biosynthesis; ko00561, glycerolipid metabolism; ko00564, glycerophospholipid metabolism; ko00591, linoleic acid metabolism; ko00600, sphingolipid metabolism; ko01040, biosynthesis of unsaturated fatty acids. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)