Effects of the lactation on cellular energy supply and aging processes in dairy cows

哺乳后的高产奶量导致奶牛代谢活动增加，从而增加脂肪组织储备库的动员。代谢性应激伴随着代谢性疾病和感染性疾病以及生育功能障碍的增加。在哺乳早期，参与衰老过程的高代谢率对奶牛持续缩短寿命和生产期可能是重要的。在哺乳早期，脂肪储备的总脂肪质量通过脂肪组织的动员而改变，导致脂肪细胞变小，细胞数量减少，即细胞程序性死亡(细胞凋亡)。由表观遗传过程控制的细胞衰老是否优先导致能量供应减少，或者两者兼而有之，是否会导致更多的凋亡尚不清楚。因此，直接参与代谢和能量过程的器官(乳腺、肝脏、脂肪组织)将由于其细胞能量供应和表观遗传(衰老)过程而被研究。通过对初产奶牛和经产奶牛的比较，将确定高产奶牛在增加生产时间和强度的情况下，通过乳汁合成所产生的影响。

The high milk yield directly after lactation results in an increased metabolic activity in dairy cows leading to increased mobilization of adipose tissue depots. The metabolic stress is accompanied by increased incidences of metabolic and infection diseases as well as fertility dysfunctions. During early lactation the enhanced metabolic rate involved in aging processes, is probably important for ongoing shortened longevity and production period of dairy cows. Total fat mass of the fat depots is changed through mobilization of adipose tissue during early lactation, leading to smaller adipocytes and a decline of the amount of cells, the programmed cell death (apoptosis). Whether preferentially cell ageing -controlled by epigenetic processes- reduced energy supply or both leads to increased apoptosis is not known. Therefore, organs directly involved in metabolic and energetic processes (mammary gland, liver, adipose tissue) will be investigated due to their cellular energy supply and epigenetic (aging) processes. Comparing primiparous and pluriparous cows, the impact of high yielding, effected through milk synthesis, in dairy cows with increased production time and intensity will be identified.