1 材料与方法
1.1 试验材料
1.2 常规营养成分含量测定
1.3 试验动物和饲养管理
表1 基础饲粮组成及营养水平(干物质基础)Table 1 Composition and nutrient levels of the basal diet (DM basis) % |
| 项目Items | 含量Content | ||
|---|---|---|---|
| 原料Ingredients | |||
| 全株玉米青贮Whole-plant corn silage | 26.63 | ||
| 苜蓿干草Alfalfa hay | 12.77 | ||
| 压片玉米Ground corn grain | 27.92 | ||
| 全棉籽Whole cotton seed | 4.42 | ||
| 糖蜜Molasses | 0.72 | ||
| 玉米蛋白粉Corn gluten meal | 0.84 | ||
| 豆粕Soybean meal | 13.62 | ||
| 菜籽粕Rapeseed meal | 3.63 | ||
| 葡萄糖Glucose | 1.88 | ||
| 脂肪酸钙Calcium fatty acid | 2.79 | ||
| 碳酸钙CaCO3 | 0.65 | ||
| 碳酸氢钠NaHCO3 | 0.52 | ||
| 氯化钠NaCl | 0.49 | ||
| 预混料Premix1) | 3.12 | ||
| 合计Total | 100.00 | ||
| 营养水平Nutrient levels2) | |||
| 泌乳净能NEL/(MJ/kg) | 1.69 | ||
| 有机物OM | 91.12 | ||
| 粗蛋白质CP | 17.73 | ||
| 粗脂肪EE | 4.67 | ||
| 淀粉Starch | 27.74 | ||
| 中性洗涤纤维NDF | 28.59 | ||
| 酸性洗涤纤维ADF | 18.64 | ||
| 粗灰分Ash | 6.25 | ||
| 钙Ca | 0.63 | ||
| 磷p | 0.56 |
1)每千克预混料含有 One kilogram of the premix contained the following:VA 250 000 IU,VD3 50 000 IU,VE 1 100 IU,Cu 250 mg,Mn 500 mg,Zn 1 000 mg,Se 20 mg,I 40 mg,Co 24 mg。2)泌乳净能依据NRC(2021)计算,计算公式为:泌乳净能(MJ/kg)=[0.024 5×饲粮可消化总养分(%)-0.12]×4.184;其余为实测值。NEL was calculated according to NRC (2021), and the calculation formula was NEL (MJ/kg)=[0.024 5×TDN(%)-0.12]×4.184; while the others were measured values. |
1.4 尼龙袋试验
1.5 瘤胃降解特性
1.5.1 饲料样品量的校正
样品逃逸率(%)=100×(空白样重-空白残渣重)/空白样重;
校正饲料样品重(g)=实际饲料样品重×(1-样品逃逸率)。
1.5.2 营养成分降解量和瘤胃降解率的计算
营养成分某时间点的降解量(g)=(校正饲料样品重×空白残渣中营养成分含量)-(该时间点残渣重×该时间点残渣中营养成分含量);
某营养成分瘤胃降解率(%)=100×该营养成分某时间点的降解量/(校正饲料样品重×空白残渣中营养成分含量)。
1.5.3 瘤胃降解参数和有效降解率的计算
1.6 数据处理与统计分析
2 结果与分析
2.1 不同生长阶段食叶草常规营养成分
表2 不同生长阶段食叶草常规营养成分(干物质基础)Table 2 Common nutrients in leaf-eating grass at different growth stages (DM basis) % |
| 项目 Items | 生长期Growing stage | 现蕾期 Squaring stage (70 d) | 盛花期 Full-bloom stage (85 d) | 结籽期 Seed-setting stage (100 d) | 均值 标准误 SEM | P值 P-value | ||
|---|---|---|---|---|---|---|---|---|
| 25 d | 45 d | 60 d | ||||||
| 有机物OM | 93.33e | 93.69d | 94.47c | 97.69a | 96.11b | 95.91b | 0.459 | <0.001 |
| 粗蛋白质CP | 31.02a | 29.38a | 27.57b | 26.15b | 19.50c | 10.27d | 2.152 | <0.001 |
| 粗脂肪EE | 4.71b | 5.30a | 4.94b | 4.06c | 3.99c | 1.44d | 0.383 | <0.001 |
| 中性洗涤纤维NDF | 40.39d | 41.38cd | 45.32cd | 48.56bc | 52.72b | 68.26a | 2.903 | <0.001 |
| 酸性洗涤纤维ADF | 16.76 | 19.05 | 14.93 | 17.94 | 16.99 | 17.77 | 0.439 | 0.060 |
| 粗灰分Ash | 6.67a | 6.31b | 5.53c | 2.31e | 3.89d | 4.09d | 0.459 | <0.001 |
| 钙Ca | 1.36a | 1.17b | 0.92c | 0.06d | 0.10d | 0.07d | 0.167 | <0.001 |
| 磷P | 0.26a | 0.20b | 0.22ab | 0.01c | 0.01c | 0.01c | 0.033 | <0.001 |
同行数据肩标不同字母表示差异显著(P<0.05),相同字母或无字母表示差异不显著(P>0.05)。下表同。 | |
In the same row, values with different letter superscripts mean significant difference (P<0.05), while with the same or no letter superscripts mean no significant difference (P>0.05). The same as below. |
2.2 不同生长阶段食叶草DM瘤胃降解特性
表3 不同生长阶段食叶草DM瘤胃降解率及降解参数Table 3 Rumen degradation rate and degradation parameters of DM in leaf-eating grass at different growth stages |
| 项目 Items | 生长期Growing stage | 现蕾期 Squaring stage (70 d) | 盛花期 Full-bloom stage (85 d) | 结籽期 Seed-setting stage (100 d) | 均值 标准误 SEM | P值 P-value | ||
|---|---|---|---|---|---|---|---|---|
| 25 d | 45 d | 60 d | ||||||
| DM瘤胃降解率Rumen degradation rate of DM/% | ||||||||
| 2 h | 24.75a | 22.72b | 20.05c | 18.12d | 17.67d | 15.71e | 0.763 | <0.001 |
| 4 h | 25.70a | 24.97a | 22.19b | 19.06c | 18.49c | 16.62d | 0.843 | <0.001 |
| 8 h | 31.18a | 29.09b | 28.33b | 28.31b | 23.26c | 19.88d | 0.945 | <0.001 |
| 12 h | 49.87a | 47.69b | 44.70c | 40.71d | 36.44e | 29.58f | 1.678 | <0.001 |
| 16 h | 58.52a | 56.68b | 53.94c | 49.13d | 43.61e | 36.60f | 1.863 | <0.001 |
| 24 h | 73.83a | 69.47b | 68.43c | 62.93d | 55.67e | 48.65f | 2.097 | <0.001 |
| 36 h | 79.72a | 77.48a | 74.76b | 68.25c | 60.60d | 53.32e | 2.310 | <0.001 |
| 48 h | 81.10a | 79.46b | 76.46c | 69.91d | 63.09e | 56.44f | 2.169 | <0.001 |
| 72 h | 82.25a | 80.52b | 78.81c | 71.79d | 65.22e | 58.61f | 2.094 | <0.001 |
| DM瘤胃降解参数Rumen degradation parameters of DM | ||||||||
| a/% | 10.68a | 9.87a | 7.29b | 6.19b | 7.57b | 7.26b | 0.415 | <0.001 |
| b/% | 75.12a | 74.24a | 74.45a | 68.10b | 59.79c | 54.57d | 1.933 | <0.001 |
| c/(%/h) | 0.06a | 0.06a | 0.06a | 0.06a | 0.06a | 0.05b | <0.001 | <0.001 |
| a+b/% | 85.79a | 84.11b | 81.74c | 74.29d | 67.36e | 61.83f | 2.156 | <0.001 |
| ED/% | 60.62a | 58.52b | 56.24c | 51.47d | 46.41e | 40.51f | 1.710 | <0.001 |
a:快速降解部分;b:慢速降解部分;c:慢速降解部分的降解速率;a+b:潜在可降解部分;ED:有效降解率。下表同。 | |
a: fast degradation part; b: slow degradation part; c: degradation rate of slow degradation part; a+b: potential degradation part; ED: effective degradation rate. The same as below. |
2.3 不同生长阶段食叶草CP瘤胃降解特性
表4 不同生长阶段食叶草CP瘤胃降解率及降解参数Table 4 Rumen degradation rate and degradation parameters of CP in leaf-eating grass at different growth stages |
| 项目 Items | 生长期Growing stage | 现蕾期 Squaring stage (70 d) | 盛花期 Full-bloom stage (85 d) | 结籽期 Seed-setting stage (100 d) | 均值 标准误 SEM | P值 P-value | ||
|---|---|---|---|---|---|---|---|---|
| 25 d | 45 d | 60 d | ||||||
| CP瘤胃降解率Rumen degradation rate of CP/% | ||||||||
| 2 h | 31.56a | 30.99a | 29.57b | 28.33c | 26.52d | 23.59e | 0.676 | <0.001 |
| 4 h | 33.94a | 32.62ab | 31.53b | 29.92c | 28.45c | 24.57d | 0.764 | <0.001 |
| 8 h | 45.85a | 43.63b | 40.34c | 39.63c | 36.29d | 30.37e | 1.223 | <0.001 |
| 12 h | 55.93a | 53.64b | 48.52c | 46.53d | 44.19e | 36.54f | 1.539 | <0.001 |
| 16 h | 67.23a | 65.53b | 62.73c | 59.74d | 55.53e | 49.49f | 1.472 | <0.001 |
| 24 h | 76.21a | 74.75b | 73.51c | 71.73d | 68.69e | 61.65f | 1.176 | <0.001 |
| 36 h | 81.57a | 80.37a | 79.54a | 75.64b | 75.42b | 65.64c | 1.311 | <0.001 |
| 48 h | 83.45a | 82.68a | 81.71b | 77.30c | 75.56d | 68.31e | 1.259 | <0.001 |
| 72 h | 85.65a | 84.84a | 82.56b | 79.15c | 77.78d | 72.44e | 1.107 | <0.001 |
| CP瘤胃降解参数Rumen degradation parameters of CP | ||||||||
| a/% | 19.89a | 19.40a | 18.16b | 17.25b | 15.94c | 14.16d | 0.495 | <0.001 |
| b/% | 66.86a | 66.73a | 67.46a | 64.22b | 64.95b | 60.94c | 0.548 | <0.001 |
| c/(%/h) | 0.07a | 0.07b | 0.06c | 0.06c | 0.06d | 0.05e | 0.002 | <0.001 |
| a+b/% | 86.76a | 86.13b | 85.62c | 81.49d | 80.88e | 75.09f | 0.988 | <0.001 |
| ED/% | 66.10a | 64.71b | 62.76c | 60.11d | 58.05e | 51.67f | 1.166 | <0.001 |
2.4 不同生长阶段食叶草NDF瘤胃降解特性
表5 不同生长阶段食叶草NDF瘤胃降解率及降解参数Table 5 Rumen degradation rate and degradation parameters of NDF in leaf-eating grass at different growth stages |
| 项目 Items | 生长期Growing stage | 现蕾期 Squaring stage (70 d) | 盛花期 Full-bloom stage (85 d) | 结籽期 Seed-setting stage (100 d) | 均值 标准误 SEM | P值 P-value | ||
|---|---|---|---|---|---|---|---|---|
| 25 d | 45 d | 60 d | ||||||
| NDF瘤胃降解率Rumen degradation rate of NDF/% | ||||||||
| 2 h | 23.96a | 22.72a | 19.63b | 17.82b | 15.51c | 14.71c | 1.054 | <0.001 |
| 4 h | 25.42a | 23.49ab | 20.67bc | 18.64cd | 16.55d | 15.69d | 1.100 | 0.002 |
| 8 h | 30.59a | 28.53b | 26.39c | 25.53c | 22.36d | 18.73e | 1.189 | <0.001 |
| 12 h | 37.56a | 35.46b | 31.62c | 30.63d | 27.32e | 25.93f | 1.241 | <0.001 |
| 16 h | 42.61a | 41.89a | 39.46b | 36.66c | 34.22d | 30.48e | 1.293 | <0.001 |
| 24 h | 49.46a | 48.53b | 46.66c | 42.29d | 39.52e | 36.29f | 1.456 | <0.001 |
| 36 h | 58.76a | 56.53ab | 53.01bc | 51.23c | 46.44d | 42.59d | 1.715 | <0.001 |
| 48 h | 64.75a | 63.62a | 60.39b | 57.07c | 51.09d | 48.54e | 1.829 | <0.001 |
| 72 h | 65.58a | 64.66ab | 62.78b | 58.42c | 52.41d | 49.89d | 1.826 | <0.001 |
| NDF瘤胃降解参数Rumen degradation parameters of NDF | ||||||||
| a/% | 18.36a | 16.59b | 13.85c | 12.38d | 10.06e | 9.73e | 0.965 | <0.001 |
| b/% | 52.80ab | 52.98ab | 53.63a | 50.34b | 45.35c | 44.20c | 1.160 | <0.001 |
| c/(%/h) | 0.04ab | 0.04ab | 0.04b | 0.04ab | 0.04a | 0.04b | <0.001 | <0.001 |
| a+b/% | 71.16a | 69.58ab | 67.48b | 62.72c | 55.40d | 53.93d | 2.035 | <0.001 |
| ED/% | 47.54a | 46.01b | 43.29c | 40.63d | 36.66e | 34.09f | 1.453 | <0.001 |
2.5 不同生长阶段食叶草ADF瘤胃降解特性
表6 不同生长阶段食叶草ADF瘤胃降解率及降解参数Table 6 Rumen degradation rate and degradation parameters of ADF in leaf-eating grass at different growth stages |
| 项目 Items | 生长期Growing stage | 现蕾期 Squaring stage (70 d) | 盛花期 Full-bloom stage (85 d) | 结籽期 Seed-setting stage (100 d) | 均值 标准误 SEM | P值 P-value | ||
|---|---|---|---|---|---|---|---|---|
| 25 d | 45 d | 60 d | ||||||
| ADF瘤胃降解率Rumen degradation rate of ADF/% | ||||||||
| 2 h | 21.97a | 19.65b | 17.55c | 16.62c | 13.39d | 11.31e | 1.089 | <0.001 |
| 4 h | 23.31a | 21.57b | 18.35c | 17.40c | 14.51d | 13.68d | 1.053 | <0.001 |
| 8 h | 26.49a | 23.74b | 21.56c | 19.78d | 18.80d | 16.44e | 0.998 | <0.001 |
| 12 h | 29.64a | 26.54b | 25.75c | 23.69d | 20.84e | 19.94f | 1.008 | <0.001 |
| 16 h | 40.29a | 38.49b | 35.54c | 34.59c | 30.43d | 28.45e | 1.256 | <0.001 |
| 24 h | 48.60a | 47.28b | 43.79c | 41.45d | 39.38e | 35.58f | 1.355 | <0.001 |
| 36 h | 52.54a | 52.58a | 46.98b | 46.88b | 42.59c | 39.44c | 1.488 | <0.001 |
| 48 h | 61.17a | 60.65a | 57.66b | 55.35c | 48.61d | 43.60e | 1.936 | <0.001 |
| 72 h | 62.59a | 61.25a | 58.52b | 56.48c | 50.39d | 46.42e | 1.749 | <0.001 |
| ADF瘤胃降解参数Rumen degradation parameters of ADF | ||||||||
| a/% | 15.62a | 13.16b | 11.04c | 10.33c | 7.66d | 6.54e | 0.933 | <0.001 |
| b/% | 52.67a | 54.57a | 54.15a | 52.66a | 46.79b | 42.82c | 1.319 | <0.001 |
| c/(%/h) | 0.04bc | 0.04bc | 0.03c | 0.03c | 0.04ab | 0.04a | 0.001 | 0.020 |
| a+b/% | 68.29a | 67.73ab | 65.19bc | 62.99c | 54.46d | 49.36e | 2.136 | <0.001 |
| ED/% | 44.12a | 42.37b | 39.33c | 37.86d | 33.81e | 30.89f | 1.384 | <0.001 |

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