日粮蛋白质和赖氨酸水平对奶牛产奶性能、氮代谢和血液指标的影响.

Effects of Various Dietary Protein or Lysine Level on Performance,Nitrogen Metabolism and Blood Parameters for Lactating Dairy Cows

本研究的目的是观察不同日粮蛋白质(CP)和赖氨酸(Lys)水平对奶牛产奶性能、氮代谢和血液指标的影响。试验采用4×4拉丁方设计,选择4头经产中国荷斯坦牛,随机接受4个日粮处理。分别为12.5%CP和0.45%Lys的日粮1、12.5%CP和0.60%Lys的日粮2、14.1%CP和0.45%Lys的日粮3及14.1%CP和0.60%Lys的日粮4。试验期共72d,分为4期,每期18d,其中每期最后4d为收集期。结果表明,无论蛋白质水平是否变化,当日粮赖氨酸水平从0.45%提高到0.60%,奶牛的产奶量、乳氮产量和氮利用率均提高,乳蛋白率略呈上升趋势;日粮赖氨酸水平还可以通过调节奶牛激素分泌和血尿素氮的水平,影响奶牛产奶性能。

A nitrogen balance experiment was performed to characterize the effects of changing dietary CP from 12.5% to 14.1% and dietary lysine from 0.45% to 0.60% on milk yield, N metabolism and blood parameters for lactating cows. Four multiparous Holstein lactating cows were used in a 4 × 4 Latin Square. Four diets were formulated to contain 12.5% CP and 0.45% Lys （Diet 1）, 12.5% CP and 0.60% Lys （Diet 2）, 14.1% CP and 0.45% Lys （Diet 3） and 14.1% CP and 0.60% Lys （Diet 4）. Each lactating cow had 4 experimental periods and each period had a 14 d adaptation, following by a 4 d total milk, faecal and urine collection. Blood samples were taken in the last day of each collection. The results showed that the cows improved the milk production and milk protein, milk N excretion and N utilization when dietary Lys increased from 0.45% to 0.60%, no matter how dietary CP changed; dietary Lys level could also manipulate hormone secretion and BUN concentration and modify the performance of dairy cows.