CHANGES IN CONCENTRATION OF CALCIUM IN BO VINE UDDER SECRETIONS RELATED TO PREDICTING PARTURITION

Nine heifers and 10 cows of the breed 'German Black Pied' were used in order to evaluate the practicability of measurement of changes in con centration of calcium in udder secretions during the preparatory stage of labour for the prediction of the time of calving. A gradual increa se in the concentration of calcium in udder secretions ante partum (a. p.) was determined. Eleven days a.p., the average concentration of cal cium was 14.2 mmol/l. Thereafter, the calcium content gradually increa sed and reached a mean value of 52.1 mmol/l sub partu (secretions of a ll udder quarters), and 52.4 mmol/l and 51.8 mmol/l in secretions of f ore and hind quarters, respectively. Despite the increase in calcium, the time of calving in individual animals could nor be predicted relia bly, or with a high probability, because the increase in calcium conte nt did not occur in all cows, the variation of the values was high, an d the differences between values during the last 48 h a.p. were only s mall.