1 材料与方法
1.1 试验材料
1.2 试验设计
表1 发酵底物组成及营养水平(干物质基础)Table 1 Composition and nutrient levels of fermentation substrates (DM basis) |
| 项目 Items | 基础饲粮 Basal diet | 缓释尿素添加比例SRU addition ratios/% | ||||
|---|---|---|---|---|---|---|
| 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | ||
| 原料Ingredients | ||||||
| 苜蓿干草Alfalfa hay | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 | 20.0 |
| 玉米青贮Corn silage | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 |
| 玉米秸秆Corn stalk | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 |
| 豆粕Soybean meal | 12.0 | 10.0 | 7.0 | 4.0 | 1.0 | |
| 麸皮Wheat bran | 15.0 | 15.0 | 15.0 | 15.0 | 12.0 | 6.0 |
| 玉米Corn | 28.0 | 29.5 | 32.0 | 34.5 | 40.0 | 46.5 |
| 缓释尿素SRU | 0.5 | 1.0 | 1.5 | 2.0 | 2.5 | |
| 预混料Premix1) | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 | 3.0 |
| 碳酸氢钠NaHCO3 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| 食盐NaCl | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 | 1.0 |
| 合计Total | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 营养水平Nutrient levels2) | ||||||
| 代谢能ME/(MJ/kg) | 9.50 | 9.45 | 9.40 | 9.36 | 9.37 | 9.45 |
| 粗蛋白质CP | 15.23 | 15.72 | 15.84 | 15.96 | 15.91 | 15.99 |
| 钙Ca | 0.45 | 0.45 | 0.44 | 0.44 | 0.43 | 0.42 |
| 磷P | 0.31 | 0.30 | 0.29 | 0.28 | 0.26 | 0.23 |
| 中性洗涤纤维NDF | 34.73 | 35.98 | 37.82 | 40.58 | 34.28 | 35.68 |
| 酸性洗涤纤维ADF | 16.23 | 16.62 | 16.00 | 16.14 | 17.08 | 15.62 |
1)每千克预混料含有 One kilogram of the premix contained the following:VA 300 000 IU,VD 35 000 IU,VE 2 000 IU,Cu 200 mg,Fe 1 800 mg,Zn 1 100 mg,Mn 750 mg,I 6 mg,Se 15 mg,NaCl 50 g。 2)代谢能为参照NY/T 816—2021所得计算值,其余均为实测值。ME was a calculated value according to NY/T 816—2021, while the others were measured values. |
1.3 体外瘤胃发酵试验
1.4 体外产气量、产气参数及瘤胃发酵参数测定
1.5 体外养分降解率测定
1.6 体外瘤胃菌群结构测定
1.7 数据处理与统计分析
2 结果与分析
2.1 SRU对滩羊体外瘤胃发酵产气量和产气参数的影响
表2 SRU对滩羊体外瘤胃发酵产气量和产气参数的影响Table 2 Effects of SRU on in vitro rumen fermentation gas production and gas production parameters of Tan sheep |
| 项目 Items | 对照组 Control group | 0.5%组 0.5% group | 1.0%组 1.0% group | 1.5%组 1.5% group | 2.0%组 2.0% group | 2.5%组 2.5% group | SEM | P值 P-value |
|---|---|---|---|---|---|---|---|---|
| 累积产气量Cumulative gas production/mL | ||||||||
| 2 h | 425.00b | 570.00a | 377.50b | 352.50b | 355.00b | 370.00b | 24.723 | 0.046 |
| 4 h | 1 020.00a | 1 015.00a | 740.00b | 697.50b | 707.50b | 660.00b | 44.221 | 0.001 |
| 6 h | 1 200.00a | 1 205.00a | 1 155.00ab | 1 062.50b | 1 067.50b | 1 040.00b | 20.534 | 0.006 |
| 8 h | 1 237.50b | 1 280.00ab | 1 440.00a | 1 402.50ab | 1 417.50a | 1 400.00ab | 23.779 | 0.020 |
| 10 h | 1 332.50b | 1 412.50b | 1 615.00a | 1 607.50a | 1 637.50a | 1 590.00a | 34.684 | 0.002 |
| 12 h | 1 415.00b | 1 495.00b | 1 745.00a | 1 742.50a | 1 785.00a | 1 735.00a | 42.309 | 0.001 |
| 24 h | 1 610.00b | 1 720.00b | 2 062.50a | 2 080.00a | 2 120.00a | 2 095.00a | 59.557 | 0.002 |
| 48 h | 1 750.00b | 1 867.50b | 2 285.00a | 2 315.00a | 2 250.00a | 2 230.00a | 64.896 | 0.001 |
| 理论最大产气量 a+b/mL | 1 672.18b | 1 814.80b | 2 271.40a | 2 293.95a | 2 233.45a | 2 199.55a | 71.179 | <0.001 |
| 产气速率c/(%/h) | 0.13 | 0.14 | 0.14 | 0.13 | 0.13 | 0.15 | 0.004 | 0.654 |
同行数据肩标无字母或相同小写字母表示差异不显著(P>0.05),不同小写字母表示差异显著(P<0.05)。下表同。 | |
In the same row, values with no letter or the same lowercase letter superscripts mean no significant difference (P>0.05), while with different lowercase letter superscripts mean significant difference (P<0.05). The same as below. |
2.2 SRU对滩羊体外养分降解率的影响
表3 SRU对滩羊体外养分降解率的影响Table 3 Effects of SRU on in vitro nutrient degradability of Tan sheep |
| 项目 Items | 对照组 Control group | 0.5%组 0.5% group | 1.0%组 1.0% group | 1.5%组 1.5% group | 2.0%组 2.0% group | 2.5%组 2.5% group | SEM | P值 P-value |
|---|---|---|---|---|---|---|---|---|
| 干物质降解率DMD | 41.04c | 67.92ab | 74.85a | 67.18b | 61.78b | 59.42b | 0.031 | 0.001 |
| 粗蛋白质降解率CPD | 44.70c | 51.20b | 69.94a | 66.99ab | 65.64ab | 62.15b | 2.829 | 0.008 |
| 中性洗涤纤维降解率 NDFD | 42.90ab | 36.18b | 45.09a | 43.46a | 43.36a | 36.62b | 1.079 | 0.013 |
| 酸性洗涤纤维降解率 ADFD | 30.04ab | 30.55ab | 36.88a | 35.90a | 27.34b | 26.32b | 1.127 | 0.003 |
2.3 SRU对滩羊体外瘤胃发酵参数的影响
表4 SRU对滩羊体外瘤胃发酵参数的影响Table 4 Effects of SRU on in vitro rumen fermentation parameters of Tan sheep |
| 项目 Items | 对照组 Control group | 0.5%组 0.5% group | 1.0%组 1.0% group | 1.5%组 1.5% group | 2.0%组 2.0% group | 2.5%组 2.5% group | SEM | P值 P-value | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| pH | 6.33 | 6.36 | 6.40 | 6.37 | 6.34 | 6.33 | 0.015 | 0.713 | |||||||||
| 氨态氮NH3-N/(mg/dL) | 9.93 | 10.00 | 10.19 | 10.05 | 10.15 | 10.08 | 0.079 | 0.989 | |||||||||
| 微生物蛋白 MCP/(mg/mL) | 1.06 | 1.05 | 0.95 | 1.03 | 0.89 | 0.86 | 0.019 | 0.623 | |||||||||
| 乙酸 Acetic acid/(mmol/L) | 6.70 | 7.10 | 7.12 | 7.19 | 6.64 | 6.55 | 0.145 | 0.908 | |||||||||
| 丙酸 Propionic acid/(mmol/L) | 3.46 | 3.25 | 3.41 | 3.38 | 3.21 | 3.19 | 0.128 | 0.976 | |||||||||
| 丁酸 Butyric acid/(mmol/L) | 2.68 | 2.63 | 2.74 | 2.69 | 2.45 | 2.48 | 0.054 | 0.798 | |||||||||
| 乙酸/丙酸 Acetic acid/propionic acid | 1.93 | 2.02 | 2.11 | 2.14 | 2.05 | 1.97 | 0.050 | 0.964 | |||||||||
| 总挥发性脂肪酸 TVFA/(mmol/L) | 14.06 | 14.01 | 14.17 | 13.98 | 13.75 | 13.58 | 0.289 | 0.751 |
2.4 SRU对滩羊体外瘤胃菌群结构的影响
2.4.1 操作分类单元(OTUs)聚类分析
2.4.2 Sobs指数与Shannon指数稀释曲线分析
2.4.3 Alpha多样性分析
表5 Alpha多样性指数Table 5 Alpha diversity indexes |
| 项目 Items | 对照组 Control group | 0.5%组 0.5% group | 1.0%组 1.0% group | 1.5%组 1.5% group | 2.0%组 2.0% group | 2.5%组 2.5% group | SEM | P值 P-value |
|---|---|---|---|---|---|---|---|---|
| Sobs指数Sobs index | 1 927.00b | 2 083.67b | 3 155.00a | 3 024.00a | 3 024.67a | 2 884.00a | 139.655 | 0.010 |
| Simpson指数 Simpson index | 0.95b | 0.96b | 0.99a | 0.98a | 0.98a | 0.98a | 0.003 | <0.001 |
| Shannon指数 Shannon index | 6.66b | 7.11b | 8.47a | 8.38a | 8.16a | 8.22a | 0.175 | <0.001 |
| Chao指数Chao index | 2 305.07b | 2 420.80b | 3 545.48a | 3 425.14a | 3 467.24a | 3 316.50a | 135.622 | 0.001 |
| ACE指数ACE index | 2 366.94b | 2 486.29b | 3 613.74a | 3 502.94a | 3 558.99a | 3 375.03ab | 144.108 | 0.005 |
| 覆盖度Coverage | 0.99 | 0.99 | 0.99 | 0.99 | 0.99 | 0.99 | <0.001 | 0.144 |
2.4.4 Beta多样性分析
2.4.5 瘤胃菌群组成与结构分析
2.4.5.1 门和属水平菌群组成
表6 SRU对滩羊体外瘤胃菌群门和属水平相对丰度的影响Table 6 Effects of SRU on relative abundance of rumen microbiota of Tan sheep in vitro at phylum and genus levels |
| 项目 Items | 对照组 Control group | 0.5%组 0.5% group | 1.0%组 1.0% group | 1.5%组 1.5% group | 2.0%组 2.0% group | 2.5%组 2.5% group | SEM | P值 P-value | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Phylum level门水平 | |||||||||||||||||
| 拟杆菌门Bacteroidota | 26.39c | 28.56c | 42.26ab | 44.14a | 37.84b | 36.63b | 1.615 | <0.001 | |||||||||
| 厚壁菌门Firmicutes | 39.54a | 37.42a | 27.85ab | 24.27b | 24.18b | 21.87b | 1.887 | 0.004 | |||||||||
| 变形菌门Pseudomonadota | 24.52 | 22.21 | 22.86 | 20.18 | 27.04 | 22.72 | 1.363 | 0.859 | |||||||||
| 疣微菌门Verrucomicrobiota | 3.66b | 4.70ab | 6.15a | 4.16b | 3.80b | 4.46ab | 0.243 | 0.020 | |||||||||
| 髌骨细菌门Patescibacteria | 2.32b | 2.68b | 3.65ab | 4.69a | 3.33ab | 3.28ab | 0.229 | 0.031 | |||||||||
| 放线菌门Actinomycetota | 1.38b | 0.82c | 1.93a | 1.67ab | 1.39b | 1.11bc | 0.156 | <0.001 | |||||||||
| 螺旋体门Spirochaetota | 0.64 | 0.84 | 0.99 | 1.24 | 0.98 | 0.66 | 0.073 | 0.165 | |||||||||
| 甲烷杆菌门 Methanobacteriota | 0.49 | 0.40 | 0.53 | 0.47 | 0.53 | 0.75 | 0.046 | 0.422 | |||||||||
| 绿弯菌门Chloroflexota | 0.12 | 0.12 | 0.32 | 0.31 | 0.49 | 0.53 | 0.054 | 0.130 | |||||||||
| 互养菌门Synergistota | 0.18 | 0.21 | 0.18 | 0.20 | 0.23 | 0.25 | 0.009 | 0.283 | |||||||||
| 属水平Genus level | |||||||||||||||||
| 木聚糖杆菌属 Xylanibacter | 11.71b | 11.17b | 21.66a | 22.13a | 20.17a | 19.84a | 1.118 | <0.001 | |||||||||
| 解琥珀酸菌属 Succiniclasticum | 9.96 | 7.27 | 6.62 | 8.86 | 7.97 | 9.04 | 0.410 | 0.199 | |||||||||
| 瘤胃杆菌属 Ruminobacter | 8.44 | 8.09 | 9.05 | 8.61 | 8.82 | 8.57 | 0.113 | 0.199 | |||||||||
| 理研菌科RC9肠道群 Rikenellaceae_RC9_ gut_group | 4.97c | 5.56bc | 9.05ab | 9.74a | 7.54b | 6.81b | 0.426 | <0.001 | |||||||||
| 克里斯滕森菌科R-7群 Christensenellaceae_ R-7_group | 2.21 | 2.93 | 2.44 | 2.46 | 3.23 | 3.11 | 0.574 | 0.329 | |||||||||
| 候选糖单胞菌属 Candidatus_Saccharimonas | 2.63 | 3.33 | 3.16 | 3.53 | 3.23 | 2.63 | 0.228 | 0.155 | |||||||||
| 琥珀酸弧菌科UCG-002 Succinivibrionaceae_ UCG-002 | 1.45 | 1.12 | 1.46 | 1.33 | 1.56 | 1.30 | 0.293 | 0.166 | |||||||||
| NK4A214群 NK4A214_group | 0.70 | 0.84 | 0.51 | 0.61 | 0.86 | 0.87 | 0.113 | 0.247 | |||||||||
| 琥珀酸弧菌属Succinivibrio | 0.52 | 0.65 | 0.82 | 0.88 | 0.43 | 0.34 | 0.072 | 0.102 | |||||||||
| 产乙酸糖发酵菌属 Saccharofermentans | 0.45 | 0.46 | 0.43 | 0.50 | 0.48 | 0.48 | 0.032 | 0.817 |
2.4.5.2 瘤胃菌群与体外养分降解率之间的相关性
图4 瘤胃菌门(A)和菌属(B)相对丰度与体外养分降解率的相关性分析DMD:干物质降解率 dry matter degradability;CPD:粗蛋白质降解率 crude protein degradability;NDFD:中性洗涤纤维降解率 neutral detergent fiber degradability;ADFD:酸性洗涤纤维降解率 acid detergent fiber degradability。 红色表示正相关,蓝色表示负相关,颜色深浅表示Spearman相关系数绝对值的大小。*表示显著相关(P<0.05),**表示极显著相关(P<0.01)。Red indicated positive correlation, blue indicated negative correlation, and the depth of the color indicated the absolute value of the Spearman correlation coefficient. * indicated significant correlation (P<0.05), and ** indicated extremely significant correlation (P<0.01). Fig.4 Correlation analysis of relative abundance of rumen bacterial phyla (A) and genera (B) with in vitro nutrient degradability |
2.5 瘤胃菌群功能预测
表7 滩羊体外瘤胃菌群KEGG一级通路丰度分析Table 7 KEGG primary pathway abundance analysis of in vitro rumen microbiota of Tan sheep |
| KEGG一级通路 KEGG primary pathways | 对照组 Control group | 0.5%组 0.5% group | 1.0%组 1.0% group | 1.5%组 1.5% group | 2.0%组 2.0% group | 2.5%组 2.5% group | SEM | P值 P-value | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 新陈代谢 Metabolism | 1 983 343.33 | 2 188 604.96 | 2 318 487.51 | 2 210 466.56 | 2 172 894.62 | 2 294 543.61 | 48 752.616 | 0.503 | |||||||||
| 遗传信息处理 Genetic information processing | 359 669.17 | 397 125.22 | 415 633.17 | 397 155.99 | 392 085.49 | 414 503.32 | 8 739.788 | 0.563 | |||||||||
| 细胞过程 Cellular processes | 128 258.93 | 132 652.47 | 110 661.54 | 103 195.11 | 110 467.26 | 109 429.76 | 3 316.597 | 0.056 | |||||||||
| 环境信息处理 Environmental information processing | 52 035.33 | 56 771.24 | 54 354.48 | 50 369.36 | 52 625.62 | 55 348.71 | 1 395.261 | 0.866 | |||||||||
| 有机系统 Organismal systems | 11 743.02 | 12 959.83 | 12 865.46 | 12 345.77 | 12 132.49 | 12 543.36 | 243.563 | 0.796 | |||||||||
| 人类疾病 Human diseases | 4 429.20 | 4 955.64 | 5 155.38 | 4 695.04 | 4 570.04 | 4 753.75 | 141.651 | 0.804 |
表8 滩羊体外瘤胃菌群KEGG二级通路丰度分析(前10)Table 8 KEGG secondary pathway abundance analysis of in vitro rumen microbiota of Tan sheep (top 10) |
| KEGG二级通路 KEGG secondary pathways | 对照组 Control group | 0.5%组 0.5% group | 1.0%组 1.0% group | 1.5%组 1.5% group | 2.0%组 2.0% group | 2.5%组 2.5% group | SEM | P值 P-value | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 辅因子与维生 素代谢 Metabolism of cofactors and vitamins | 392 539.75 | 398 650.39 | 423 236.00 | 403 193.40 | 398 614.93 | 418 604.62 | 9 227.742 | 0.570 | |||||||||
| 碳水化合物代谢 Carbohydrate metabolism | 334 582.66c | 371 538.46ab | 394 764.36a | 373 620.03ab | 368 864.70b | 368 864.70b | 8 692.913 | 0.043 | |||||||||
| 氨基酸代谢 Amino acid metabolism | 331 813.79c | 364 751.90ab | 376 372.56a | 361 423.62ab | 354 276.59b | 353 753.01b | 7 369.234 | 0.036 | |||||||||
| 复制与修复 Replication and repair | 178 411.53 | 174 511.92 | 183 794.27 | 176 205.44 | 172 802.54 | 182 728.19 | 3 842.443 | 0.538 | |||||||||
| 能量代谢 Energy metabolism | 139 758.33 | 154 753.19 | 165 234.21 | 157 816.15 | 154 610.13 | 162 773.34 | 3 625.246 | 0.486 | |||||||||
| 脂质代谢 Lipid metabolism | 113 991.94 | 127 385.71 | 130 385.59 | 123 795.62 | 121 729.72 | 128 023.65 | 2 808.357 | 0.691 | |||||||||
| 翻译 Translation | 90 584.01 | 99 921.53 | 103 458.58 | 99 029.70 | 97 491.10 | 103 338.31 | 2 096.797 | 0.603 | |||||||||
| 核苷酸代谢 Nucleotide metabolism | 52 030.25 | 57 623.48 | 61 395.51 | 58 741.76 | 57 523.03 | 60 692.51 | 1 324.943 | 0.463 | |||||||||
| 信号转导 Signal transduction | 8 846.32 | 9 787.45 | 8 214.35 | 7 605.84 | 8 109.03 | 8 431.37 | 244.792 | 0.177 | |||||||||
| 膜运输 Membrane transport | 43 186.12 | 46 978.95 | 46 139.17 | 42 762.33 | 44 515.65 | 46 916.56 | 1 188.808 | 0.898 |

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