1 材料与方法
1.1 试验动物与处理
表1 饲粮组成及营养水平(干物质基础)Table 1 Composition and nutrient levels of diets (DM basis) |
| 项目 Items | 组别Groups | ||||||
|---|---|---|---|---|---|---|---|
| LSN | MSN | HSN | |||||
| 原料Ingredients/% | |||||||
| 玉米Corn | 15.42 | 20.54 | 25.60 | ||||
| 小麦麸Wheat bran | 13.22 | 7.18 | 2.22 | ||||
| 菜籽粕Rapeseed meal | 2.94 | 4.49 | 4.30 | ||||
| 棉籽粕Cottonseed meal | 7.58 | 7.00 | 7.50 | ||||
| 豆皮Soybean hull | 4.36 | 4.31 | 3.90 | ||||
| 酵母Yeast | 0.15 | 0.15 | 0.15 | ||||
| 脂肪酸钙Fatty acid calcium | 1.06 | 1.06 | 1.06 | ||||
| 膨化尿素Puffing urea | 0.26 | 0.26 | 0.26 | ||||
| 碳酸钙CaCO3 | 0.28 | 0.28 | 0.28 | ||||
| 小苏打NaHCO3 | 1.11 | 1.11 | 1.11 | ||||
| 食盐NaCl | 0.84 | 0.84 | 0.84 | ||||
| 预混料Premix1) | 2.78 | 2.78 | 2.78 | ||||
| 全株青贮玉米Whole corn silage | 20.00 | 25.00 | 30.00 | ||||
| 麦秸Wheat straw | 20.00 | 15.00 | 7.50 | ||||
| 玉米秸杆Corn straw | 10.00 | 10.00 | 12.50 | ||||
| 合计Total | 100.00 | 100.00 | 100.00 | ||||
| 营养水平Nutrient levels2) | |||||||
| 总能GE/(MJ/kg) | 18.40 | 18.46 | 18.51 | ||||
| 粗蛋白质CP/% | 13.32 | 13.33 | 13.34 | ||||
| 中性洗涤纤维NDF/% | 47.11 | 44.07 | 41.02 | ||||
| 酸性洗涤纤维ADF/% | 27.95 | 26.57 | 24.81 | ||||
| 钙Ca/% | 0.87 | 0.86 | 0.84 | ||||
| 磷P/% | 0.48 | 0.45 | 0.42 | ||||
| 淀粉Starch/% | 19.20 | 22.50 | 26.07 | ||||
| 粗脂肪EE/% | 3.36 | 3.46 | 3.57 | ||||
| 淀粉/中性洗涤纤维SN | 0.41 | 0.51 | 0.64 | ||||
1)每千克预混料含有Contained the following per kg of the premix:VA 2 100 000 IU,VD3 800 000 IU,VE 21 000 IU,Cu 6.2 g,Mn 9.54 g,Zn 12.42 g,I 210 mg,Se 180 mg,Co 75 mg。 | |
2)营养水平均为实测值。Nutrient levels were all measured values. |
1.2 饲养管理
1.3 指标测定与方法
1.3.1 生长性能
1.3.2 屠宰性能
1.3.3 肉品质
1.4 数据统计与分析
2 结果
2.1 生长性能
表2 不同SN比例饲粮对育肥牦牛生长性能的影响Table 2 Effects of diets with different SN ratios on growth performance of fattening yaks |
| 项目 Items | 组别Groups | SEM | P值 P-value | ||
|---|---|---|---|---|---|
| LSN | MSN | HSN | |||
| 始重IBW/kg | 249.77 | 247.60 | 245.07 | 6.32 | 0.871 |
| 末重FBW/kg | 332.43 | 343.11 | 350.03 | 5.64 | 0.054 |
| 增重WG/kg | 82.67c | 95.51b | 104.97a | 3.01 | <0.001 |
| 干物质采食量DMI/(kg/d) | 6.93 | 7.09 | 7.20 | 0.25 | 0.687 |
| 平均日增重ADG/(g/d) | 718.84c | 830.55b | 912.75a | 26.16 | <0.001 |
| 料重比F/G | 9.64a | 8.53ab | 7.88b | 0.42 | 0.025 |
同行数据肩标不同小写字母表示差异显著(P<0.05),无字母或相同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 no letter or the same letter superscripts mean no significant difference (P>0.05). The same as below. |
2.2 屠宰性能
表3 不同SN比例饲粮对育肥牦牛内脏器官重量的影响Table 3 Effects of diets with different SN ratios on organ weight of fattening yakskg |
| 项目 Items | 组别Groups | SEM | P值 P-value | ||
|---|---|---|---|---|---|
| LSN | MSN | HSN | |||
| 内脏脂肪重Visceral fat weight | 3.22 | 3.47 | 3.71 | 0.25 | 0.472 |
| 心脏重Heart weight | 1.51 | 1.80 | 1.67 | 0.16 | 0.556 |
| 肝脏重Liver weight | 4.58 | 5.16 | 5.45 | 0.40 | 0.348 |
| 脾脏重Splenic weight | 0.72 | 0.83 | 0.65 | 0.11 | 0.525 |
| 肺脏重Lung weight | 3.98 | 4.06 | 3.70 | 0.45 | 0.868 |
| 肾脏重Kidney weight | 0.70 | 0.65 | 0.70 | 0.03 | 0.598 |
表4 不同SN比例饲粮对育肥牦牛消化器官重量的影响Table 4 Effects of diets with different SN ratios on digestive organ weight of fattening yakskg |
| 项目 Items | 组别Groups | SEM | P值 P-value | ||
|---|---|---|---|---|---|
| LSN | MSN | HSN | |||
| 瘤胃Rumen | 5.56a | 5.11a | 4.36b | 0.21 | 0.010 |
| 网胃Reticulum | 0.82 | 0.87 | 0.80 | 0.06 | 0.684 |
| 瓣胃Omasum | 1.64 | 1.76 | 1.54 | 0.12 | 0.458 |
| 皱胃Abomasum | 0.87 | 0.89 | 0.82 | 0.04 | 0.498 |
| 小肠Small intestine | 2.37 | 2.27 | 2.20 | 0.07 | 0.354 |
| 大肠Large intestine | 1.77 | 1.56 | 1.60 | 0.11 | 0.464 |
| 盲肠Cecum | 0.82 | 0.81 | 0.83 | 0.08 | 0.990 |
表5 不同SN比例饲粮对育肥牦牛头、尾、皮和蹄重的影响Table 5 Effects of diets with different SN ratios on head, tail, fur and hoof weight of fattening yakskg |
| 项目 Items | 组别Groups | SEM | P值 P-value | ||
|---|---|---|---|---|---|
| LSN | MSN | HSN | |||
| 头重Head weight | 19.73 | 19.76 | 19.23 | 0.74 | 0.857 |
| 蹄总重Total hoof weight | 7.34 | 6.60 | 6.78 | 0.22 | 0.192 |
| 尾重Tail weight | 1.59 | 1.52 | 1.63 | 0.09 | 0.718 |
| 皮重Fur weight | 33.22 | 33.18 | 34.20 | 1.11 | 0.785 |
表6 不同SN比例饲粮对育肥牦牛胴体性状的影响Table 6 Effects of diets with different SN ratios on carcass traits of fattening yaks |
| 项目 Items | 组别Groups | SEM | P值 P-value | ||
|---|---|---|---|---|---|
| LSN | MSN | HSN | |||
| 胴体长Carcass length/cm | 121.25 | 127.25 | 128.00 | 2.47 | 0.203 |
| 胴体胸深Chest depth of carcass/cm | 63.00 | 62.75 | 64.00 | 0.98 | 0.723 |
| 胴体深Carcass depth/cm | 61.75 | 61.00 | 62.25 | 1.60 | 0.866 |
| 胴体后腿围Hind leg girth of carcass/cm | 49.00 | 50.00 | 50.25 | 1.02 | 0.723 |
| 胴体后腿长Hind leg length of carcass/cm | 60.50 | 62.25 | 63.50 | 2.42 | 0.780 |
| 胴体后腿宽Hind leg breadth/cm | 21.25 | 22.25 | 22.00 | 0.65 | 0.555 |
| 大腿肌肉厚Thigh muscle thickness/cm | 11.25 | 11.75 | 12.00 | 0.51 | 0.594 |
| 眼肌面积Loin muscle area/cm2 | 44.25 | 48.50 | 49.25 | 3.12 | 0.551 |
表7 不同SN比例饲粮对育肥牦牛屠宰性能的影响Table 7 Effects of diets with different SN ratios on slaughter performance of fattening yaks |
| 项目 Items | 组别Groups | SEM | P值 P-value | ||
|---|---|---|---|---|---|
| LSN | MSN | HSN | |||
| 胴体重Carcass weight/kg | 177.24 | 181.08 | 186.56 | 3.55 | 0.244 |
| 净肉重Net meat weight/kg | 152.46 | 156.15 | 161.33 | 3.36 | 0.238 |
| 骨重Bone weight/kg | 24.78 | 24.93 | 25.23 | 0.57 | 0.856 |
| 屠宰率Slaughter rate/% | 50.35b | 51.40ab | 52.87a | 0.56 | 0.036 |
| 净肉率Clear meat ratio/% | 43.31b | 44.33ab | 45.72a | 0.56 | 0.042 |
| 胴体产肉率Meat production rate of carcass/% | 86.01 | 86.23 | 86.47 | 0.30 | 0.605 |
2.3 肉品质
表8 不同SN比例饲粮对育肥牦牛肉品质的影响Table 8 Effects of diets with different SN ratios on muscle quality of fattening yaks |
| 项目 Items | 组别Groups | SEM | P值 P-value | ||
|---|---|---|---|---|---|
| LSN | MSN | HSN | |||
| 熟肉率Cooked meat rate/% | 63.32 | 64.67 | 68.32 | 1.16 | 0.090 |
| 剪切力Shear force/N | 7.90a | 7.02ab | 5.82b | 0.42 | 0.025 |
| pH | 5.93 | 6.02 | 5.73 | 0.19 | 0.605 |
| 亮度L* | 26.65 | 26.86 | 31.33 | 1.11 | 0.058 |
| 红度a* | 9.48 | 10.03 | 11.20 | 0.93 | 0.490 |
| 黄度b* | 6.00 | 10.80 | 13.95 | 3.66 | 0.446 |

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