不同粗饲料分级指数与碳水化合物平衡指数组合饲粮对泌乳中期奶牛产奶性能及血清生化指标的影响

Effects of Different Roughage Grading Index and Carbohydrate Balance Index Combinational Diets on Milk Performance and Serum Biochemical Indexes of Mid-Lactating Dairy Cows

本试验在相同能量和蛋白质水平下,研究不同粗饲料分级指数(GI)与碳水化合物平衡指数(CBI)组合饲粮对泌乳中期奶牛产奶性能及血清生化指标的影响。通过GI筛选粗饲料最佳组合,以谷物的种类和含量改变CBI[CBI=物理有效中性洗涤纤维(peNDF)/谷物瘤胃可降解淀粉(RDSG)]。试验采用2×2双因素析因设计,饲粮GI分别为10.83和10.33,CBI分别为1.48和1.62。选24头胎次、体重接近的泌乳中期荷斯坦奶牛,随机分为4组(每组6头),分别饲喂不同GI与CBI组合饲粮。结果显示:1) GI和CBI对奶牛的干物质采食量及主要营养物质采食量均无显著影响(P>0.05),且两者的交互作用不显著(P>0.05)。GI对各时间点(正试期第6、13、20、27、34天)及平均产奶量无显著影响(P>0.05),CBI对除第6天外的各时间点及平均产奶量均有显著影响(P<0.05)。同一GI下,随着CBI的减小,产奶量增大,以GI=10.83、CBI=1.48组产奶量相对较高。GI和CBI以及两者的交互作用对乳脂率、乳蛋白率、乳尿素氮含量和乳体细胞数均没有显著影响(P>0.05)。GI=10.33、CBI=1.48组乳脂率相对较高,GI=10.83、CBI=1.62组乳尿素氮含量相对较高,GI=10.33、CBI=1.62组乳体细胞数相对较低。2)GI和CBI对奶牛各时间点(正试期第6、13、20、27、34天)及平均血清总蛋白、白蛋白、尿素氮、总胆固醇、甘油三酯、葡萄糖、β-羟丁酸含量与谷丙转氨酶、谷草转氨酶活性均无显著影响(P>0.05),且两者的交互作用不显著(P>0.05)。由此得出,饲粮GI=10.83、CBI=1.48时泌乳中期奶牛的产奶量相对较高,GI=10.33、CBI=1.48时泌乳中期奶牛的乳品质相对较好。在饲粮CBI=1.48的条件下,蛋白质和脂类消化利用情况以GI=10.83时较优,在糖类代谢方面以GI=10.33时较优。

The effects of different roughage grading index (GI) and carbohydrate balance index (CBI) combinational diets were studied on milk performance and serum biochemical indexes of mid-lactating dairy cows under the same dietary energy and protein levels in this experiment. The optimal combination of roughage was screened by GI,and the CBI [CBI = physically effective neutral detergent fiber (peNDF)/ruminal degradable starch from grain (RDSG) ] was changed by the type and content of the grain. A 2×2 two-factor factorial design was used with dietary GI of 10.83 and 10.33 and CBI of 1.48 and 1.62,respectively. Twenty-four midlactating Holstein dairy cows were selected and randomly divided into 4 groups with 6 cows per group,and the cows in the 4 groups were fed different GI and CBI combinational diets. The results showed as follows: 1) GI and CBI had no significant effects on dry matter intake and main nutrient intakes of dairy cows (P>0.05),and there were no significant interactions between GI and CBI (P>0.05). GI had no significant effects on average milk yield and the milk yield at different time points (the 6 th,13 th,20 th,27 th and 34 th day of the trial period) (P> 0. 05),and CBI had significant effects on average milk yield and the milk yield at different time points except the 6 th day (P<0.05). At the same GI,the milk yield increased with the CBI decreasing,and the group of GI = 10.83 and CBI = 1.48 had the relatively higher milk yield. The milk fat percentage,milk protein percentage,milk urea nitrogen content and milk somatic cell count were not significantly affected by GI,CBI and their interaction (P>0.05). The milk fat percentage of group GI = 10.33 and CBI = 1.48 was relatively higher,the milk urea nitrogen content of group GI = 10.83 and CBI = 1.62 was relatively higher,and the milk somatic cell count of group GI = 10.33 and CBI = 1.62 was relatively lower. 2) GI and CBI had no significant effects on the contents of total protein (TP),albumin (ALB),urea nitrogen (UN),total cholesterol (TC),triglyceride (TG),glucose (GLU),β-hydroxybutyrate (BHBA) and the activities of alanine transaminase (ALT) and aspartate aminotransferase (AST) in serum at different time points (the 6 th,13 th,20 th,27 th and 34 th day of the trial period) and their average values (P>0.05),and there were no significant interactions between GI and CBI (P>0.05). It is concluded that the milk yield is relatively higher when dairy cows fed the diets with GI = 10.83 and CBI = 1.48 in the mid-lactation period,and the milk quality is relatively well when dairy cows fed the diet with GI = 10.33 and CBI = 1.48 in the middle lactation. Under the condition of dietary CBI = 1.48,the digestion and absorption of protein and lipids are better when GI = 10.83,and the carbohydrate metabolism is better when GI = 10.33.