饲粮中性洗涤纤维水平对泌乳高峰期奶牛生产性能、营养物质表观消化率及血清指标的影响

Effects of Neutral Detergent Fiber Levels in Diet on Milk Performance,Nutrient Apparent Digestibility and Serum Indices of Dairy Cows during Peak Lactation Period

本试验旨在研究饲粮中性洗涤纤维(NDF)水平对泌乳高峰期奶牛生产性能、营养物质表观消化率及血清指标的影响。选用8头泌乳天数为(50±15)d的泌乳高峰期荷斯坦奶牛,按照4×4拉丁方设计,4个处理分别饲喂NDF水平为25.05%、28.05%、31.22%和34.19%的4种饲粮;共进行4期试验,每期21 d,其中预试期14 d,正试期7 d。结果表明:1)随饲粮NDF水平的升高,奶牛干物质采食量、产奶量、乳糖产量、乳蛋白产量和氮利用效率线性降低(P<0.05);乳脂率和乳尿素氮浓度线性增加(P<0.05);饲料转化效率和乳脂产量呈线性增加的趋势(P=0.05);乳蛋白率呈线性降低的趋势(P=0.08);但4%标准乳产量、乳糖率变化不显著(P>0.05)。2)随饲粮NDF水平的升高,NDF和酸性洗涤纤维(ADF)的表观消化率线性增加(P<0.05)。3)随饲粮NDF水平的升高,血清葡萄糖、胰岛素浓度线性降低(P<0.05);血清非酯化脂肪酸、β-羟丁酸及尿素氮浓度线性增加(P<0.05);血清甘油三酯(P=0.06)和皮质醇(P=0.07)浓度呈线性增加的趋势;但血清总胆固醇浓度无显著变化(P>0.05)。综合得出,饲粮中25.05%和34.19%NDF对泌乳高峰期奶牛生产性能和能氮利用都有不利影响,28.05%NDF比31.22%NDF的饲粮能氮利用更为合理,生产性能更佳,建议泌乳高峰期奶牛饲粮NDF水平为28.05%。

This experiment was conducted to investigate the effects of neutral detergent fiber（NDF） levels in diet on milk performance,nutrient apparent digestibility and serum indices of dairy cows during peak lactation period.Eight Holstein dairy cows [（50 ± 15） days in milk]were selected in a 4 × 4 Latin square design.The NDF level in diets was 25.05%,28.05%,31.22% and 34.19%,respectively.The experiment had 4 periods with21 days per period,and each period had 14 days for pre-test and 7 days for formal test.The results showed as follows： 1） with the increase of NDF level in diet,the dry matter intake,milk yield,lactose yield,milk protein yield and nitrogen efficiency decreased linearly（P〈0.05）; milk fat percentage and milk urea nitrogen concentration increased linearly（P〈0.05）; feed efficiency and milk fat yield tended to increase linearly（P = 0.05）;milk protein percentage tended to decrease linearly（P = 0.08）; while 4% fat corrected milk yield and lactose percentage were not significantly influenced（P〈0.05）.2） With the increase of NDF level in diet,the apparent digestibility of NDF and acid detergent fiber increased linearly（P〈0.05）.3） With the increase of NDF level in diet,serum glucose and insulin concentrations reduced linearly（P〈0.05）; serum non-esterified fatty acids,β-hydroxybutyrate and urea nitrogen concentrations increased linearly（P〈0.05）; serum triglyceride（P = 0.06）and cortisol concentrations（P = 0.07） tended to increase linearly,but total cholesterol concentration was not significantly influenced（P〈0.05）.In conclusion,both the 25.05% NDF and 34.19% NDF in diet have negative influence on energy-nitrogen utilization and milk performance,while the 28.05% NDF level can be more reasonable for nitrogen utilization and better milk performance than 31.22% NDF.It is suggested that the supplemental level of NDF be 28.05% for dairy cows in the peak lactation period.