【作者】 李红梅；

【导师】 李艳飞；

【作者基本信息】 东北农业大学 ， 临床兽医学， 2006， 硕士

【摘要】 将健康围产期中国荷斯坦奶牛30头随机均分为三组,预产前28天分别饲喂奶牛标准日粮(能量摄入100%组)、超标准20%日粮(能量摄入120%组)和低标准20%日粮(能量摄入80%组),产后各组奶牛均饲喂标准的产奶日粮,至产后56天结束。通过自动生化分析仪、放射免疫测定技术、定量逆转录PCR(RT-PCR)等现代分子生物学技术,对围产期奶牛的生产性能(干物质摄入量、日产奶量、体重)、循环血液中葡萄糖、胰高血糖素和胰岛素水平及肝脏糖异生关键酶(丙酮酸羧化酶和磷酸烯醇式丙酮酸羧激酶)基因表达水平等进行测定,旨在研究干奶期不同能量摄入水平对围产期奶牛糖异生作用的影响。试验结果如下:1.干奶期高能饲喂奶牛,干物质摄入减少(达16%),产乳量下降(达15%),失重增加,能量负平衡加重;而干奶期低能饲喂奶牛,干物质摄入增加(达6%),产奶量增加(达6%),产后失重减少,能量负平衡减轻且持续时间缩短。2.低能量日粮饲喂干奶期奶牛,血液葡萄糖浓度升高,而干奶期高能饲喂奶牛,血液葡萄糖浓度降低,但组间差异均不显著。3.低能量日粮饲喂干奶期奶牛,肝脏PC mRNA和PEPCK mRNA丰度升高,而干奶期高能饲喂奶牛,肝脏PC mRNA和PEPCK mRNA丰度降低,组间差异显著或极显著。4.低能量日粮饲喂干奶期奶牛,血液胰高血糖素浓度增加,胰岛素浓度下降,GN/INS增高,促进肝糖异生,而干奶期高能饲喂奶牛则相反,组间差异显著性水平不同。5.新生牛肝细胞培养中,胰岛素浓度与胰岛素受体mRNA丰度呈负相关(r=0.849,P<0.05)。干奶期低能饲喂奶牛,肝脏胰岛素受体mRNA丰度变化有效调控血糖水平,血糖浓度升高,而高能饲喂奶牛则相反。本实验说明产前适当降低能量摄入可提高奶牛产后干物质摄入量,上调PC mRNA和PEPCK mRNA丰度,增强肝糖异生能力,有助于缓解产后泌乳消耗大量葡萄糖所造成的能量负平衡和营养应激。而高能饲养奶牛因其对血糖水平的调节能力弱,所以更容易引发能量负平衡。本研究为围产期奶牛能量代谢障碍性疾病的防治奠定了分子水平的实验基础。更多还原

【Abstract】 Thirty healthy periparturient Chinese-Holstein dairy cows were randomly allocated into three groups to study the effect and the regulatory mechanism of different energy intake during the dry period on glyconeogenesis. The cows were fed with 100% energy diet, 120% energy diet and 80% energy diet, respectively, beginning at the day 28 prior to parturition. After calving, all the cows were offered the lactation ration ad libitum up to the day 56 postpartum. The levels of some metabolites and hormones in the peripheral blood and of insulin receptor(IR) mRNA, pyruvate carboxylase (PC) mRNA and phosphoenolpyruvate carboxykinase (PEPCK) mRNA abundance in the liver were measured by radioimmunoassay, quantitative reverse transcription polymerase chain reaction(RT-PCR)and automatic biochemistry analyzer. The results showed as follows:1.The cows fed with high energy diet during the dry period reduced 6% of the dry matter intake (DMI) and 21% of milk yields (MY). It increased the loss in body weight and aggravated the negative energy balance, while the cow fed with low energy diet during the dry period increased 6% of the DMI and 6% of MY. It had a less loss in body weight after parturition, thus not only relieve the negative energy balance but also shorten the duration.2.The cows fed with low energy diet during the dry period had the highest level of blood glucose compared with the other two groups of cows,however,there was no significant difference among the groups.3.The cows fed with low energy diet during the dry period had the highest abundance of PC mRNA and PEPCK mRNA in liver compared with the other two groups of cows and there was significant difference among the groups.4.The cows fed with low energy diet during the dry period, had an increasing plasma concentrations of glucagons, reducing plasma concentration of insulin and increasing GN/INS and improved the liver glyconeogenesis. While the cows fed with high energy diet during the dry period had opposite results.5.The concentration of insulin in hepatocyte culture of calf showed inverse correlation with the abundance of insulin receptor(IR). The abundance of IR mRNA in the cows fed with low更多还原