1 材料与方法
1.1 伦理声明
1.2 试验材料
1.3 试验设计
表1 A~F组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 in groups A to F (DM basis)% |
| 项目 Items | 缓释尿素添加水平 SRU supplemental level/% | |||||
|---|---|---|---|---|---|---|
| 0 | 3.2 | 6.4 | 9.6 | 12.8 | 16.0 | |
| 原料 Ingredients | ||||||
| 豆粕 Soybean meal | 16.0 | 12.8 | 9.6 | 6.4 | 3.2 | |
| 缓释尿素 SRU | 3.2 | 6.4 | 9.6 | 12.8 | 16.0 | |
| 玉米 Corn | 22.0 | 22.0 | 22.0 | 22.0 | 22.0 | 22.0 |
| 苜蓿干草 Alfalfa hay | 22.0 | 22.0 | 22.0 | 22.0 | 22.0 | 22.0 |
| 玉米青贮 Corn silage | 40.0 | 40.0 | 40.0 | 40.0 | 40.0 | 40.0 |
| 合计 Total | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 | 100.0 |
| 营养水平 Nutrient levels | ||||||
| 干物质 DM | 90.97 | 90.86 | 91.55 | 92.93 | 91.00 | 90.61 |
| 粗脂肪 EE | 2.31 | 2.09 | 2.50 | 2.66 | 2.73 | 2.31 |
| 粗蛋白质 CP | 14.10 | 14.85 | 14.94 | 15.54 | 15.32 | 15.60 |
| 中性洗涤纤维 NDF | 35.43 | 35.03 | 35.90 | 36.24 | 35.31 | 38.49 |
| 酸性洗涤纤维 ADF | 18.91 | 19.22 | 20.44 | 20.78 | 21.44 | 22.01 |
| 粗灰分 Ash | 5.44 | 5.57 | 5.71 | 5.91 | 6.25 | 6.22 |
| 淀粉 Starch | 10.38 | 6.91 | 6.66 | 9.60 | 8.67 | 8.41 |
| 有机物 OM | 85.53 | 85.29 | 85.84 | 87.02 | 84.75 | 84.39 |
| 泌乳净能 NEL/(MJ/kg) | 6.92 | 6.79 | 6.66 | 6.53 | 6.40 | 6.27 |
干物质为风干基础;泌乳净能参照NRC(2001)计算,其余营养水平为实测值。 | |
DM was air-dry basis; NEL was calculated according to NRC (2001), while the other nutrient levels were measured values. |
1.4 体外瘤胃发酵试验及样品采集
1.5 指标测定及方法
1.5.1 营养成分含量及养分降解率测定
DMD(%)=100×(DM1-DM2)/DM1;
CPD(%)=100×(CP1-CP2)/CP1。
1.5.2 瘤胃发酵参数测定
1.5.3 产气动力学参数测定
1.5.4 细菌16S rRNA基因测序及生物信息学分析
1.6 数据统计与分析
2 结果与分析
2.1 SRU及EHCP对瘤胃体外发酵产气量及产气动力学参数的影响
表2 SRU及EHCP对瘤胃体外发酵产气量及产气动力学参数的影响Table 2 Effects of SRU and EHCP on in vitro rumen fermentation gas production and gas production kinetic parameters |
| 项目 Items | 累积产气量 Cumulative gas production/(mL/g DM) | 产气动力学参数 Gas production kinetic parameters | |||||||
|---|---|---|---|---|---|---|---|---|---|
| 4 h | 8 h | 12 h | 16 h | 24 h | 理论最大产气量 Theoretical maximum gas production/ (mL/g DM) | 曲线陡度 参数 Curve steepness parameter | 达到1/2理论 最大产气量的时间 Time of reaching 1/2 theoretical maximum gas production/h | ||
| 组别 Groups | |||||||||
| A | 12.00 | 51.00 | 88.60bcde | 117.00 | 157.60 | 177.14 | 2.42 | 9.65 | |
| B | 9.20 | 54.20 | 89.60bcd | 120.60 | 158.20 | 177.18 | 2.46 | 9.69 | |
| C | 4.60 | 42.80 | 80.80e | 109.00 | 142.60 | 178.75 | 2.10 | 9.58 | |
| D | 4.60 | 45.80 | 82.20de | 111.80 | 144.20 | 178.88 | 2.08 | 9.58 | |
| E | 6.80 | 47.20 | 89.60bcd | 119.00 | 154.40 | 178.92 | 2.18 | 9.66 | |
| F | 2.80 | 43.00 | 85.00cde | 113.80 | 149.20 | 178.86 | 2.09 | 9.58 | |
| A1 | 17.67 | 70.40 | 104.60a | 132.40 | 157.60 | 177.21 | 2.58 | 9.92 | |
| B1 | 15.20 | 64.80 | 103.80a | 132.60 | 160.20 | 177.98 | 2.50 | 9.55 | |
| C1 | 11.00 | 64.80 | 104.00a | 130.40 | 153.00 | 178.04 | 2.57 | 9.71 | |
| D1 | 10.20 | 55.80 | 94.60b | 123.20 | 152.60 | 176.49 | 2.97 | 9.92 | |
| E1 | 9.50 | 55.50 | 91.50bc | 122.50 | 153.25 | 177.24 | 2.46 | 9.70 | |
| F1 | 5.75 | 49.75 | 93.50b | 121.75 | 145.25 | 178.13 | 2.31 | 9.67 | |
| SEM | 1.291 | 2.858 | 2.782 | 2.996 | 3.189 | 0.698 | 0.156 | 0.093 | |
| SRU添加水平 SRU supplemental level/% | |||||||||
| 0 | 14.83a | 60.70a | 96.60a | 124.70ab | 157.60a | 177.18 | 2.50 | 9.78 | |
| 3.2 | 12.20a | 59.50ab | 96.70a | 126.60a | 159.20a | 177.58 | 2.48 | 9.62 | |
| 6.4 | 7.80b | 53.80bc | 92.40ab | 119.70bc | 147.80b | 178.40 | 2.34 | 9.64 | |
| 9.6 | 7.40b | 50.80cd | 88.40b | 117.50c | 148.40b | 177.68 | 2.53 | 9.75 | |
| 12.8 | 8.15b | 51.35cd | 90.55b | 120.75abc | 153.83ab | 178.08 | 2.32 | 9.68 | |
| 16.0 | 4.28c | 46.38d | 89.25b | 117.78c | 147.23b | 178.49 | 2.20 | 9.62 | |
| SEM | 0.913 | 2.021 | 1.967 | 2.119 | 2.392 | 0.494 | 0.110 | 0.656 | |
| EHCP添加水平 EHCP supplemental level/% | |||||||||
| 0 | 6.67b | 47.33b | 85.97b | 115.20b | 151.03 | 178.29 | 2.22b | 9.62b | |
| 0.5 | 11.55a | 60.18a | 98.67a | 127.14a | 153.65 | 177.52 | 2.57a | 9.74a | |
| SEM | 0.576 | 1.167 | 1.136 | 1.223 | 1.302 | 0.285 | 0.064 | 0.038 | |
| P值 P-value | |||||||||
| SRU | <0.001 | <0.001 | 0.016 | 0.021 | <0.001 | 0.353 | 0.227 | 0.632 | |
| EHCP | <0.001 | <0.001 | <0.001 | <0.001 | 0.125 | 0.064 | <0.001 | 0.030 | |
| SRU×EHCP | 0.609 | 0.057 | 0.016 | 0.098 | 0.210 | 0.342 | 0.174 | 0.232 | |
SRU:缓释尿素;EHCP:酶解棉籽蛋白;SRU×EHCP:缓释尿素与酶解棉籽蛋白的交互作用。同列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。 | |
SRU: slow-release urea; EHCP: enzymatically hydrolyzed cottonseed protein; SRU×EHCP: the interaction between slow-release urea and enzymatically hydrolyzed cottonseed protein. In the same column, values with no letter or the same small letter superscripts mean no significant difference (P>0.05), while with different small letter superscripts mean significant difference (P<0.05). The same as below. |
2.2 SRU及EHCP对瘤胃体外发酵参数的影响
表3 SRU及EHCP对瘤胃体外发酵参数的影响Table 3 Effects of SRU and EHCP on in vitro rumen fermentation parameters |
| 项目 Items | pH | 氨态氮 NH3-N/(mg/mL) | 微生物蛋白 MCP/(mg/mL) |
|---|---|---|---|
| 组别 Groups | |||
| A | 6.20g | 4.76 | 15.74 |
| B | 6.23efg | 5.41 | 16.10 |
| C | 6.24def | 5.78 | 14.47 |
| D | 6.27def | 6.18 | 16.70 |
| E | 6.34bc | 6.95 | 17.55 |
| F | 6.41a | 7.50 | 19.16 |
| A1 | 6.29bcde | 4.60 | 17.46 |
| B1 | 6.29cde | 5.49 | 18.54 |
| C1 | 6.30cde | 5.51 | 20.54 |
| D1 | 6.21fg | 5.94 | 20.73 |
| E1 | 6.30bcd | 6.63 | 20.17 |
| F1 | 6.35ab | 7.19 | 21.35 |
| SEM | 0.018 | 0.175 | 0.786 |
| SRU添加水平 SRU supplemental level/% | |||
| 0 | 6.25c | 4.68e | 16.60c |
| 3.2 | 6.26c | 5.45d | 17.32bc |
| 6.4 | 6.27c | 5.64d | 17.50bc |
| 9.6 | 6.24c | 6.06c | 18.72ab |
| 12.8 | 6.32b | 6.79b | 18.86ab |
| 16.0 | 6.38a | 7.34a | 20.25a |
| SEM | 0.022 | 0.124 | 0.556 |
| EHCP添加水平 EHCP supplemental level/% | |||
| 0 | 6.28 | 6.10 | 16.62b |
| 0.5 | 6.29 | 5.89 | 19.80a |
| SEM | 0.014 | 0.072 | 0.321 |
| P值 P-value | |||
| SRU | <0.001 | <0.001 | 0.001 |
| EHCP | 0.420 | 0.053 | <0.001 |
| SRU×EHCP | 0.002 | 0.882 | 0.074 |
2.3 SRU及EHCP对瘤胃体外发酵VFA含量的影响
表4 SRU及EHCP对瘤胃体外发酵VFA含量的影响Table 4 Effects of SRU and EHCP on in vitro rumen fermentation VFA contents |
| 项目 Items | 乙酸 Acetate/ (mmol/L) | 丙酸 Propionate/ (mmol/L) | 丁酸 Butyrate/ (mmol/L) | 异戊酸 Isovalerate/ (mmol/L) | 戊酸 Valerate/ (mmol/L) | 乙丙比 A/P | |
|---|---|---|---|---|---|---|---|
| 组别 Groups | |||||||
| A | 28.80 | 17.11 | 27.90 | 0.85 | 2.43 | 2.16 | |
| B | 24.58 | 14.14 | 22.32 | 0.71 | 1.73 | 2.24 | |
| C | 27.77 | 15.88 | 23.41 | 0.73 | 1.87 | 2.02 | |
| D | 30.47 | 17.04 | 26.51 | 0.78 | 2.10 | 1.98 | |
| E | 30.73 | 17.11 | 24.40 | 0.76 | 1.83 | 2.02 | |
| F | 33.02 | 18.14 | 25.38 | 0.80 | 1.88 | 2.05 | |
| A1 | 35.77 | 20.80 | 28.17 | 1.11 | 2.35 | 2.11 | |
| B1 | 33.28 | 18.96 | 23.41 | 0.98 | 1.88 | 2.14 | |
| C1 | 35.75 | 20.43 | 25.66 | 1.00 | 2.02 | 2.03 | |
| D1 | 38.18 | 21.48 | 25.37 | 1.23 | 1.93 | 2.01 | |
| E1 | 38.82 | 21.21 | 23.37 | 0.95 | 1.79 | 2.06 | |
| F1 | 39.79 | 21.57 | 24.20 | 0.92 | 1.79 | 1.93 | |
| SEM | 1.741 | 0.926 | 1.440 | 0.084 | 0.126 | 0.076 | |
| SRU添加水平 SRU supplemental level/% | |||||||
| 0 | 32.29bc | 18.95a | 28.03a | 0.98 | 2.39a | 2.14 | |
| 3.2 | 28.93c | 16.55b | 22.86c | 0.85 | 1.81b | 2.19 | |
| 6.4 | 31.76bc | 18.15ab | 24.53bc | 0.86 | 1.94b | 2.02 | |
| 9.6 | 34.33ab | 19.26a | 25.94ab | 1.00 | 2.02b | 2.00 | |
| 12.8 | 34.78ab | 19.16a | 23.88bc | 0.85 | 1.81b | 2.04 | |
| 16.0 | 36.40a | 19.85a | 24.79bc | 0.86 | 1.83b | 1.99 | |
| SEM | 1.232 | 0.655 | 1.019 | 0.060 | 0.089 | 0.063 | |
| EHCP添加水平 EHCP supplemental level/% | |||||||
| 0 | 29.23b | 16.57b | 24.98 | 0.77b | 1.97 | 2.08 | |
| 0.5 | 36.93a | 20.74a | 25.03 | 1.03a | 1.96 | 2.05 | |
| SEM | 0.712 | 0.379 | 0.589 | 0.035 | 0.051 | 0.028 | |
| P值 P-value | |||||||
| SRU | 0.002 | 0.017 | 0.013 | 0.239 | <0.001 | 0.112 | |
| EHCP | <0.001 | <0.001 | 0.958 | <0.001 | 0.847 | 0.501 | |
| SRU×EHCP | 0.994 | 0.975 | 0.805 | 0.525 | 0.756 | 0.902 | |
2.4 SRU及EHCP对瘤胃体外发酵养分降解率影响
表5 SRU及EHCP对瘤胃体外发酵养分降解率的影响Table 5 Effects of SRU and EHCP on in vitro rumen fermentation nutrient degradation rates% |
| 项目 Items | 干物质降解率 DMD | 粗蛋白质降解率 CPD | |
|---|---|---|---|
| 组别 Groups | |||
| A | 58.01f | 42.00g | |
| B | 59.65e | 51.07f | |
| C | 60.35e | 57.95e | |
| D | 60.03e | 61.88de | |
| E | 59.65e | 64.60bcd | |
| F | 59.76e | 71.15a | |
| A1 | 62.02d | 61.91cde | |
| B1 | 62.58d | 62.41cd | |
| C1 | 63.10cd | 62.98cd | |
| D1 | 64.18bc | 64.06bcd | |
| E1 | 65.20ab | 68.75ab | |
| F1 | 66.17a | 65.97bc | |
| SEM | 0.550 | 1.514 | |
| SRU添加水平 SRU supplemental level/% | |||
| 0 | 60.01d | 51.96d | |
| 3.2 | 61.12c | 56.74c | |
| 6.4 | 61.72bc | 60.47b | |
| 9.6 | 62.10abc | 62.97b | |
| 12.8 | 62.42ab | 66.68a | |
| 16.0 | 62.97a | 68.56a | |
| SEM | 0.386 | 1.073 | |
| EHCP添加水平 EHCP supplemental level/% | |||
| 0 | 59.57b | 58.11b | |
| 0.5 | 63.87a | 64.35a | |
| SEM | 0.222 | 0.619 | |
| P值 P-value | |||
| SRU | <0.001 | <0.001 | |
| EHCP | <0.001 | <0.001 | |
| SRU×EHCP | 0.012 | <0.001 | |
2.5 SRU及EHCP对瘤胃体外发酵细菌群落结构的影响
2.5.1 瘤胃体外发酵细菌菌群多样性分析
表6 SRU及EHCP对瘤胃体外发酵细菌α多样性的影响Table 6 Effects of SRU and EHCP on in vitro rumen fermentation bacterial α-diversity |
| 项目 Items | Sobs指数 Sobs index | Ace指数 Ace index | Chao指数 Chao index | Shannon指数 Shannon index | Simpson指数 Simpson index |
|---|---|---|---|---|---|
| 组别 Groups | |||||
| A | 139.20 | 142.08 | 141.33 | 2.92 | 0.14 |
| B | 146.20 | 148.93 | 148.43 | 3.05 | 0.12 |
| C | 140.60 | 142.76 | 142.32 | 2.85 | 0.16 |
| D | 149.60 | 153.04 | 153.34 | 3.03 | 0.13 |
| E | 149.60 | 153.59 | 152.79 | 3.03 | 0.12 |
| F | 149.60 | 152.45 | 151.76 | 3.09 | 0.11 |
| A1 | 152.40 | 157.55 | 156.26 | 3.23 | 0.09 |
| B1 | 135.40 | 137.40 | 138.10 | 2.94 | 0.14 |
| C1 | 151.40 | 155.39 | 153.77 | 3.21 | 0.09 |
| D1 | 136.20 | 139.00 | 137.75 | 2.91 | 0.14 |
| E1 | 135.20 | 136.70 | 135.92 | 2.95 | 0.13 |
| F1 | 139.40 | 142.00 | 142.98 | 3.02 | 0.13 |
| SEM | 7.013 | 7.778 | 7.776 | 0.176 | 0.032 |
| SRU添加水平 SRU supplemental level/% | |||||
| 0 | 145.80 | 149.82 | 148.80 | 3.07 | 0.12 |
| 3.2 | 140.80 | 143.16 | 143.27 | 3.00 | 0.13 |
| 6.4 | 146.00 | 149.07 | 148.04 | 3.03 | 0.12 |
| 9.6 | 142.90 | 146.02 | 145.54 | 2.97 | 0.14 |
| 12.8 | 142.40 | 145.14 | 144.36 | 2.99 | 0.13 |
| 16.0 | 144.50 | 147.22 | 147.37 | 3.05 | 0.12 |
| SEM | 5.012 | 5.503 | 5.542 | 0.127 | 0.019 |
| EHCP添加水平 EHCP supplemental level/% | |||||
| 0 | 145.80 | 148.81 | 148.32 | 3.00 | 0.13 |
| 0.5 | 141.67 | 144.67 | 144.12 | 3.05 | 0.12 |
| SEM | 2.884 | 3.168 | 3.192 | 0.073 | 0.012 |
| P值 P-value | |||||
| SRU | 0.973 | 0.959 | 0.977 | 0.992 | 0.991 |
| EHCP | 0.317 | 0.317 | 0.358 | 0.616 | 0.649 |
| SRU×EHCP | 0.181 | 0.156 | 0.188 | 0.572 | 0.553 |
图1 ASV水平Venn图A、B、C、D、E、F、A1、B1、C1、D1、E1和F1分别表示A组、B组、C组、D组、E组、F组、A1组、B1组、C1组、D1组、E1组和F1组。下图同。 Fig.1 Venn diagram of ASV level A, B, C, D, E, F, A1, B1, C1, D1, E1 and F1 represent group A, group B, group C, group D, group E, group F, group A1, group B1, group C1, group D1, group E1 and group F1, respectively. The same as below. |
2.5.2 瘤胃体外发酵细菌菌群组成分析
图3 SRU及EHCP对瘤胃体外发酵门水平菌群组成的影响Firmicutes:厚壁菌门;Bacteroidota:拟杆菌门;Proteobacteria:变形菌门;Spirochaetota:螺旋体门;Actinobacteriota:放线菌门;Euryarchaeota:广古菌门;Verrucomicrobiota:疣微菌门;Fibrobacterota:纤维杆菌门;Cyanobacteria:蓝细菌门;Planctomycetota:浮霉菌门 ;Chloroflexi:绿弯菌门;Patescibacteria:髌骨细菌门;Elusimicrobiota:迷踪菌门; Desulfobacterota:脱硫杆菌门;Armatimonadota:装甲菌门;Others:其他。 Fig.3 Effects of SRU and EHCP on in vitro rumen fermentation bacterial composition at phylum level |
图4 SRU及EHCP对瘤胃体外发酵属水平菌群组成的影响Prevotella:普雷沃氏菌属;Ruminococcus:瘤胃球菌属;Rikenellaceae_RC9_gut_group:理研菌科RC9肠道群;Eubacterium_ruminantium_group:反刍真杆菌群;Norank_f_Muribaculaceae:未定级鼠杆菌科;Streptococcus:链球菌属;Lachnospiraceae_NK3A20_group:毛螺菌科NK3A20群;Butyrivibrio:丁酸弧菌属;Selenomonas:月形单胞菌属;Treponema:密螺旋体属;Prevotellaceae_UCG-003:普雷沃氏菌菌科;UCG-003 Lactobacillus:乳杆菌属;Christensenellaceae_R-7_group:克里斯滕森氏菌科R-7群;NK4A214_group:NK4A214群;Others:其他。 Fig.4 Effects of SRU and EHCP on in vitro rumen fermentation bacterial composition at genus level |
2.5.3 Mantel-test相关性分析
图7 Mantel-test相关性分析热图*:显著相关(P<0.05);**:极显著相关(P<0.01);***:极显著相关(P<0.001)。*: significant correlation (P<0.05); **: extremely significant correlation (P<0.01); ***: extremely significant correlation (P<0.001). Mantel’s p:Mantel-test P值 Mantel-test P-value;Relationship:相关关系;positive:正相关;negative:负相关;Mantel’s r:Mantel-test相关系数 Mantel-test correlation coefficient;Correlation:相关性;Different_bacterial_genus:差异菌属;CPD:粗蛋白质降解率 crude protein degradability;DMD:干物质降解率 dry matter degradability;Valerate:戊酸;Isovalerate:异戊酸;Butyrate:丁酸;Propionate:丙酸;Acetate:乙酸;MCP:微生物蛋白 microbial protein;NH3-N:氨态氮 ammonia nitrogen。 Fig.7 Mantel-test correlation analysis heatmap |
