Investigations were conducted on two groups of dairy cows, housed into the structures differed considering the systems of feeding and maintenance /structure I was free-stand, concrete barn; structure II - tethered, litter bedding barn including pasture during summer/. Cows selected for an experimental trials, /3 and h months of pregnancy/, were clinically examined and the blood was taken for hematology and biochemistry assignments. The procedure was repeated in 8 and 9 month of pre-delivery period. The quality of silage, fed during the pregnancy, was estimated. Among of blood indicators, the greatest variations from the physiological standards were referred to ketone bodies and' acid-base balance parameters. One can suppose, that the reason of variations was the a low quality of silage, composed too large part of cows diet. Evaluating the course of periparturient period, it appeared, that increased level of ketone bodies and acid-base balance disorders, were accompanied by the frequent number of disease incident's, like placenta detention, uterine mucus membrane inflammation, post-parturition paralysis, delayed uterus involution and udders inflammation.