Abstract: In order to understand the incidence of ketosis in postpartum dairy cows in a large-scale pasture,86 postpartum dairy cows were randomly selected to track and detect the incidence of ketosis at 1,7,14 and 21 days postpartum,and the correlation between ketosis and parity and lactation was analyzed. The results showed that the incidence rate of ketosis in cows at 1 d,7 d, 14 d and 21 d after birth was 2.32%,24.42%,11.63% and 4.65% respectively. With the increase of parity,the incidence rate of ketosis increased,and the incidence rate of 3~6 fetuses was higher. The incidence rate of subclinical ketosis and clinical ketosis cows increased with the increase of daily milk production. The results showed that there was a positive correlation between the incidence rate of ketosis ,parity and milk yield.

Key words: cow, β- Hydroxybutyric acid, clinical ketosis, subclinical ketosis, testing