维生素A在泌乳奶牛消化道内的动态变化研究

选择3头条件一致的荷斯坦奶牛，安装永久性的瘤胃瘘管、十二指肠瘘管和回肠瘘管，用Co-ETDA做标记物。采用3×3拉丁方设计研究了不同维生素A添加水平对奶牛瘤胃、十二指肠、回肠和血液中维生素A浓度的影响，以及维生素A在小肠中的吸收情况，研究结果表明：瘤胃、十二指肠、回肠和血液中维生素A浓度随着维生素A剂量增加而极显著上升（P〈0.01），其中回肠末端维生素A浓度上升的幅度随着添加剂量的增加而加大，其余三者中维生素A浓度上升的幅度随着添加剂量的增加而逐步降低。小肠中维生素A的吸收量随着维生素A剂量的增加而极显著上升（P〈0.01），但上升的幅度随着添加剂量的增加而逐步降低。

Study on Dynamic Change of Vitamin A in Alimentary Canal of Lactating Holsteins

In this ex perimen t, three Holsteins fitted with permanent rumen fistulae, proximal duodenum fistulae and ileum fistulae respectively were used in 3×3 Latin square design and ETDA-Co was used as marker to determine the effect of different levels of VA supplemented in diets on concentration of VA in rumen, duodenum, ileum and blood, as well as the absorption of VA in small intestine. The results indicated that the concentration of VA in rumen, duodenum, ileum and blood mounted up remarkably（P〈0.01 ）with the concentration of VA increased in diets. The rising amplitude in terminal ileum increased with VA increasing, while the rising amplitude in the other three reduced with VA increasing. The deposition of vitamin A in small intestine also increased; there were very significant difference in concentration of VA at different sampling time（P〈0.01 ）. The rising amplitude in small intestine reduced with VA increasing.