Effect of the first and second postpartum partial milking on blood serum calcium concentration in dairy cows

Abstract

Parturient paresis and subclinical hypocalcemia are frequent metabolic disorders in dairy cows postpartum. The aim of this study was to determine the effect of postpartum partial milking in the first two milkings on blood serum calcium concentration in dairy cows. Twenty multiparous Holstein dairy cows were randomized into two groups. Cows of group 1 (n = 10) were partially milked at the first and second milking postpartum. Cows of group 2 (n = 10) were completely milked. Blood samples were collected from all animals 5–7 days before calving, within 30 min after calving, and 4, 8, 12, 16, 20, 24, 28, and 32 h after calving for determination of serum calcium (Ca), phosphorus (P), and magnesium (Mg) concentrations. Colostrum production was registered and sampled in the first and second milking. Concentration of Ca in colostrum was determined by atomic absorption spectrophotometry. Serum Ca and P concentrations decreased in both groups after parturition (P < 0.05) and remained low during 32 h postpartum with no difference observed between groups (P > 0.05). Serum concentrations of Mg were stable in all samples and no statistical difference was observed between groups (P > 0.05). Colostrum production was higher in completely milked cows only in the first postpartum milking (P < 0.05), but there was no difference between groups at the second milking. Total Ca secretion in colostrum was higher in the complete milking group at the first and second postpartum milking. Colostrum Ca secretion increased at the second milking with respect to the first one in both groups (P < 0.05). There was no correlation between serum Ca and colostrum Ca (P > 0.05). In this study, the partial milking of colostrum in the first and second milking postpartum did not prevent subclinical hypocalcemia in dairy cows.