1 材料与方法
1.1 试验时间和试验地点
1.2 试验动物与试验设计
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 | |||
| 燕麦草Oat hay | 5.49 | ||
| 小麦草Wheat grass | 19.78 | ||
| 青贮玉米Corn silage | 57.69 | ||
| 精料补充料Concentrate supplement1) | 17.04 | ||
| 合计Total | 100.00 | ||
| 营养水平Nutrient levels2) | |||
| 干物质Dry matter | 92.32 | ||
| 有机物Organic matter | 91.39 | ||
| 粗蛋白质Crude protein | 12.58 | ||
| 粗脂肪Ether extract | 1.85 | ||
| 粗灰分Crude ash | 8.61 | ||
| 中性洗涤纤维Neutral detergent fiber | 61.58 | ||
| 酸性洗涤纤维Acid detergent fiber | 37.52 | ||
| 总能Gross energy/(MJ/kg) | 5.81 | ||
| 钙Calcium | 0.77 | ||
| 磷Phosphorus | 0.42 | ||
| 非结构性碳水化合物 Non-fibrous carbohydrate | 15.38 | ||
| 中性洗涤纤维/非结构性碳水化合物 Neutral detergent fiber/non-fibrous carbohydrate | 4.00 |
1)精料补充料主要成分:麦麸、豆粕、菜籽粕、玉米蛋白粉、石粉和氯化钠,其粗蛋白质含量≥35%,粗纤维含量≤22%,粗灰分含量≤9%,钙含量0.5%~1.0%,磷含量0.7%~0.9%,氯化钠含量1%~2%。The main ingredients of the concentrate supplement: wheat bran, soybean meal, rapeseed meal, corn gluten meal, limestone and sodium chloride, with its crude protein content ≥ 35%. crude fiber content ≤ 22%, crude ash content ≤ 9%, calcium content 0.5% to 1.0%, phosphorus content 0.7% to 0.9%, sodium chloride content 1% to 2%. 2)非纤维性碳水化合物和中性洗涤纤维/非结构性碳水化合物为计算值,非纤维性碳水化合物=1-(中性洗涤纤维+粗蛋白质+粗脂肪+粗灰分),其他营养水平为实测值。Non-fibrous carbohydrate and neutral detergent fiber/non-fibrous carbohydrate were calculated values, non-fibrous carbohydrate=1-(neutral detergent fiber+crude protein+ether extract+crude ash), while the other nutrient levels were measured values. |
1.3 饲养管理
1.4 样品采集与指标测定
1.4.1 饲粮样品采集与营养成分含量测定
1.4.2 生长性能测定
1.4.3 营养物质表观消化率测定
1.4.4 瘤胃气体排放量测定
1.5 数据统计分析
2 结果
2.1 不同生理阶段(18、21、24月龄)荷斯坦后备奶牛的生长性能
表2 不同生理阶段(18、21、24月龄)荷斯坦后备奶牛的生长性能Table 2 Growth performance of Holstein heifers at different physiological periods (18, 21 and 24 months of age) |
| 项目 Items | 组别Groups | P值 P-value | ||
|---|---|---|---|---|
| 18月龄 18 months of age | 21月龄 21 months of age | 24月龄 24 months of age | ||
| 初始体重Initial body weight/kg | 512.2±11.9c | 548.0±6.9b | 608.1±6.0a | <0.01 |
| 终末体重Final body weight/kg | 526.2±11.8c | 554.7±6.5b | 614.5±6.0a | <0.01 |
| 平均日增重Average daily gain/(kg/d) | 0.50±0.02a | 0.24±0.01b | 0.23±0.01c | <0.01 |
| 干物质采食量Dry matter intake/(kg/d) | 9.59±0.13c | 10.23±0.04b | 12.18±0.06a | <0.01 |
| 总能摄入量Gross energy intake/(MJ/d) | 205.09±1.30c | 218.61±0.83b | 260.46±2.76a | <0.01 |
2.2 不同生理阶段(18、21、24月龄)荷斯坦后备奶牛的营养物质表观消化率
表3 不同生理阶段(18、21、24月龄)荷斯坦后备奶牛的营养物质表观消化率Table 3 Nutrient apparent digestibility of Holstein heifers at different physiological periods (18, 21 and 24 months of age) % |
| 项目 Items | 组别Groups | P值 P-value | ||
|---|---|---|---|---|
| 118月龄 18 months of age | 21月龄 21 months of age | 24月龄 24 months of age | ||
| 干物质Dry matter | 69.58±0.11c | 74.07±0.10b | 75.38±0.17a | <0.01 |
| 有机物Organic matter | 73.22±0.08 | 77.67±0.07 | 77.49±0.66 | 0.76 |
| 粗蛋白质Crude protein | 76.81±0.56 | 80.32±0.26 | 76.16±0.39 | 0.28 |
| 粗脂肪Ether extract | 81.17±1.29 | 82.08±1.71 | 84.95±1.19 | 0.17 |
| 中性洗涤纤维Neutral detergent fiber | 68.25±1.54 | 72.24±1.31 | 73.51±0.87 | 0.63 |
| 酸性洗涤纤维Acid detergent fiber | 60.34±1.21 | 63.57±1.08 | 64.31±0.96 | 0.72 |
2.3 不同生理阶段(18、21、24月龄)荷斯坦后备奶牛的瘤胃CH4和CO2排放
表4 不同生理阶段(18、21、24月龄)荷斯坦后备奶牛的瘤胃CH4和CO2排放Table 4 Ruminal CH4 and CO2 emissions of Holstein heifers at different physiological periods (18, 21 and 24 months of age) |
| 项目 Items | 组别groups | P值 P-value | ||
|---|---|---|---|---|
| 18月龄 18 months of age | 21月龄 21 months of age | 24月龄 24 months of age | ||
| 甲烷排放量CH4 emission/(g/d) | 207.8±8.5c | 275.1±25.2b | 321.1±31.8a | <0.01 |
| 二氧化碳排放量CO2 emission/(g/d) | 5 636.3±221.1c | 6 559.3±106.7b | 7 267.7±122.1a | <0.01 |
| 甲烷/代谢体重 CH4/metabolizable body weight/(g/kg) | 1.91±0.09c | 2.40±0.17b | 2.61±0.24a | <0.01 |
| 甲烷/干物质采食量 CH4/dry matter intake/(g/kg) | 21.67±0.28c | 26.90±0.78a | 26.36±0.83b | <0.01 |
| 甲烷/有机物采食量 CH4/organic matter intake/(g/kg) | 29.61±0.38c | 34.64±1.00a | 34.01±1.07b | <0.01 |
| 甲烷/中性洗涤纤维采食量 CH4/neutral detergent fiber intake/(g/kg) | 51.69±0.45c | 60.46±0.87a | 58.28±1.53b | <0.01 |
| 甲烷/二氧化碳CH4/CO2 | 0.037±0.002c | 0.042±0.001b | 0.044±0.001a | <0.01 |
图1 不同生理阶段(18、21、24月龄)荷斯坦后备奶牛的瘤胃甲烷能和甲烷能/总能摄入量数据柱形标注不同小写字母表示差异显著(P<0.05)。 Fig.1 Ruminal CH4 energy and CH4 energy/gross energy intake of Holstein heifers at different physiological periods (18, 21 and 24 months of age) Value columns with different small letters mean significant difference (P<0.05). |
