血浆酶活力动态变化特征在揭示奶牛酮病致病机理中的作用

Dynamic change roles of plasma enzyme characters on revealing pathogenesis of ketosis in dairy cows

通过对16头荷斯坦奶牛分娩前后血浆葡萄糖、酮体含量以及丙氨酸氨基转移酶(ALT)、天门冬氨酸氨基转移酶(AST)、γ-谷氨酰基转移酶(GGT)、鸟氨酸氨基甲酰转移酶(OCT)的活性进行动态跟踪检测,以探讨荷斯坦奶牛分娩前后酮体等血液指标的动态变化特征以及各指标间的动态相关性,揭示奶牛酮病的高发时间以及与血酮、血糖等酮病指标相关性密切的肝功能指标酶变化特征。结果表明,奶牛肝功能损伤出现在血酮、血糖出现异常之前;被检酶的峰值出现在产后14d,而血酮峰值出现在产后28d,血糖最低值出现在产后35d;亚临床酮病牛各项指标处在异常范围的时间较长,机体对许多被检指标调节缓慢且不稳定;在非酮病、亚临床酮病牛GGT和血酮均存在显著相关性,而ALT、AST与血酮、血糖的相关性均不显著。揭示了肝脏功能损伤在前、酮病发生在后的时序特征,反映出肝脏功能与酮病发病机理之间的联系。因奶牛酮体含量在产后2～6周较高,3～4周最高,此期是监控酮病的重要时期。

The present study was undertaken to elucidate dynamic changes in blood biochemical indexes and to correlate different indexes （alanine aminotransferase ALT, aspartate aminotransferase AST, γ-glutamyl transferase GGT, ornithine carbamyl transferase OCT）in Holstein cows. For this, high morbidity time of ketosis and changes in enzyme （related to ketone and glucose metabolism） associated with liver functions have also been analysed. The samples were taken from 16 Holstein cows to determine the plasma ketone and glucose contents and ALT, AST, GGT and OCT activities at pre-and-post parturition （about 10 days）. The results showed that damages in liver functions in cows occurred before they suf- fered from ketosis. The peak of different enzyme activities and ketone accumulation was at the 14^th and 28^th day of postpartum period, respectively, and the lowest glucose level was observed at the 35^th day of postpartum period. All indexes of cows including sub-clinical ketosis have been found to be in abnormal range for a long time with slow and unstable regulation. There was significant correlation between GGT and ketone content in non-ketostic and sub-clinical ketostie cows, while no significant correlation has been found between ALT, AST, ketone, glucose content. These results indicated the damage characteristics of liver function before ketosis and helped in understanding the relationship between liver function and pathogenesis mechanism of ketosis. The best monitoring stage of ketosis was found to be at 3-4 weeks of postpartum period for the highest ketone concentration in cow.