[Changes in the acid-base index of blood in dairy cows in relation to the seasonal composition of feed rations and phases of the reproductive cycle].

The changes in the acid-base indices of the blood of dairy cows in different stages of reproduction cycle were studied in relation to the composition of feed ration in the autumn, winter, spring and summer feeding seasons. The cows were in the following stages of their reproduction cycle: Group I the fourth to sixth month of gravidity, II eighth to ninth month of gravidity, III one to two months after calving. The seasonal composition of feed ration was demonstrated to exert a significant influence on the acid-base balance of the blood of cows in the studied stages of reproduction. A considerable occurrence of metabolic acidoses with different levels of compensation was observed when the cows were given the autumn and winter feed rations. Subclinical acid-base disorders of different directions (metabolic and respiratory alkaloses, acidoses) frequently occurred in the green feeding season. The frequency of acid-base disorders as a result of incorrect nutrition was found to be the highest in highly pregnant cows (group II) and in those one to two months after parturition (group III), i. e. in the periods with a significant influence on the reproduction process. On the whole, the best situation as to the acid-base balance was found in cows in the fourth to sixth month of their gravidity, irrespective of the seasonal effect of feed ration.