Key Laboratory of Buffalo Genetics, Breeding and Reproduction Technology, Guangxi Buffalo Research Institute, Chinese Academy of Agricultural Sciences, Nanning, Guangxi, China.
Institute of Animal and Dairy Sciences, University of Agriculture, Faisalabad, Faisalabad, Punjab, Pakistan.
PeerJ. 2022 Dec 14;10:e14309. doi: 10.7717/peerj.14309. eCollection 2022.
Mulberry flavonoids can modulate the composition of rumen microbiota in ruminants to improve nutrient digestibility, owing to their strong biological activities. This study aimed to explore the effect of mulberry leaf flavonoids (MLF) on rumen bacteria, fermentation kinetics, and metagenomic functional profile in water buffalo. Forty buffaloes (4 ± 1 lactations) with almost same body weight (av. 600 ± 50 Kg) and days in milk (90 ± 20 d) were randomly allocated to four treatments having different levels of MLF: 0 g/d (control), 15 g/d (MLF15), 30 g/d (MLF30), and 45 g/d (MLF45) supplemented in a basal diet. After 35 days of supplementation, rumen contents were collected to determine rumen fermentation parameters. The 16S rRNA gene sequencing was performed to elucidate rumen bacteria composition. The obtained taxonomic data were analyzed to explore the rumen bacteriome and predict the associated gene functions and metabolic pathways. Results demonstrated a linear increase ( < 0.01) in rumen acetate, propionate, and total VFAs in the MLF45 group as compared to control. No effect of treatment was observed on rumen pH and butyrate contents. Acetate to propionate ratio in the MLF45 group linearly and quadratically decreased ( = 0.001) as compared to MLF15 and control groups. Similarly, MLF45 linearly increased ( < 0.05) the microbial protein (MCP) and NH-N as compared to other treatments. Treatment adversely affected ( < 0.01) almost all alpha diversity parameters of rumen bacteria except Simpson index. MLF promoted the abundance of Proteobacteria while reducing the relative abundances of Actinobacteria, Acidobacteria, Chloroflexi, and Patescibacteria. The MLF supplementation tended to substantially reduce (0.05 < < 0.1) the abundance of Actinobacteria, and Patescibacteria while completely eliminating Acidobacteria ( = 0.029, Chloroflexi = 0.059, and Gemmatimonadetes ( = 0.03) indicating the negative effect of flavonoids on the growth of these bacteria. However, MLF45 tended to substantially increase ( = 0.07) the abundance (~21.5%) of . The MLF treatment exhibited negative effect on five genera by significantly reducing (Sphingomonas) or eliminating (Arthobactor, unclassified_c__Actinobacteria, norank_c__Subgroup_6, norank_o__Saccharimonadales, and Nocardioides) them from the rumen microbiota. Pearson correlation analysis revealed 3, 5 and 23 positive correlations of rumen bacteria with milk yield, rumen fermentation and serum antioxidant parameters, respectively. A positive correlation of MCP was observed with three bacterial genera (Acetobacter, Enterobacter, and Klebsiella). The relative abundance of Pseudobutyrivibrio and Empedobacter also showed a positive correlation with the ruminal acetate and propionate. The present study indicated 45 g/d as an appropriate dose of MLF which modulated rumen bacteria and its functional profile in water buffalo.
桑树叶黄酮可通过调节反刍动物瘤胃微生物群落组成来改善养分消化率，这与其较强的生物学活性有关。本研究旨在探讨桑叶黄酮（MLF）对水牛瘤胃细菌、发酵动力学和宏基因组功能谱的影响。选择 40 头体况和产奶天数相近的（平均体重 600 ± 50 Kg，产奶天数 90 ± 20 d）水牛，随机分为 4 个处理组，每组 10 头，分别饲喂基础日粮+0 g/d（对照组）、15 g/d（MLF15）、30 g/d（MLF30）和 45 g/d（MLF45）的 MLF。35 d 后，收集瘤胃液以测定瘤胃发酵参数。采用 16S rRNA 基因测序分析瘤胃细菌组成。对获得的分类学数据进行分析，以探究瘤胃细菌组，并预测相关基因功能和代谢途径。结果表明，与对照组相比，MLF45 组瘤胃乙酸、丙酸和总 VFA 线性增加（ < 0.01）。处理对瘤胃 pH 和丁酸含量无影响。与 MLF15 和对照组相比，MLF45 组的乙酸/丙酸比值线性和二次降低（ = 0.001）。同样，与其他处理相比，MLF45 线性增加（ < 0.05）微生物蛋白（MCP）和 NH-N。处理组除 Simpson 指数外，几乎所有瘤胃细菌的 α 多样性参数均受到不良影响（ < 0.01）。MLF 促进了变形菌门的丰度，而降低了放线菌门、酸杆菌门、绿弯菌门和 Patescibacteria 的相对丰度。MLF 补充剂倾向于大量减少（0.05 < < 0.1）Actinobacteria 和 Patescibacteria 的丰度，而完全消除了 Acidobacteria（ = 0.029、Chloroflexi = 0.059 和 Gemmatimonadetes = 0.03），表明黄酮类化合物对这些细菌的生长有负面影响。然而，MLF45 倾向于大量增加（ = 0.07）的丰度（~21.5%）。MLF 处理对 5 个属产生了负面影响，通过显著减少（Sphingomonas）或消除（Arthobactor、unclassified_c__Actinobacteria、norank_c__Subgroup_6、norank_o__Saccharimonadales 和 Nocardioides）这些细菌从瘤胃微生物群中消失。Pearson 相关性分析显示，瘤胃细菌与产奶量、瘤胃发酵和血清抗氧化参数分别有 3、5 和 23 个正相关。MCP 与 3 个细菌属（Acetobacter、Enterobacter 和 Klebsiella）呈正相关。Pseudobutyrivibrio 和 Empedobacter 的相对丰度也与瘤胃乙酸和丙酸呈正相关。本研究表明，45 g/d 的 MLF 是调节水牛瘤胃细菌及其功能谱的适宜剂量。
