AbstractData were obtained from 89 Holstein cows, distributed among seven commercial herds, to evaluate the incidence of metabolic disorders during the periparturient transition period. The herds were enrolled in the Dairy Herd Improvement Program (DHIP) and were routinely visited by veterinarians, who diagnosed any metabolic disorders. The cows were observed every two weeks to evaluate body condition score (1 to 5 scale), to discern clinical disorders and to obtain blood samples for chemical analyses. Clinical metabolic diseases were not diagnosed, but 34% of the cows showed sub-clinical hypocalcaemia (blood calcium less than 7.9 mg/dl) and 14% had blood glucose levels less than 39.9 mg/dl. Although not significant (P greater than 0.05), milk production was higher at the second and third milk weighings in the normal cows than in those with sub-clinical hypocalcaemia (27.5 and 25.6 vs. 25.1 and 23.6 kg, respectively). The interval between parturition and first service was shorter in cows with normal blood calcium levels than in those that suffered sub-clinical hypocalcaemia (74 vs. 91 days, P less than 0.05). Mean body condition score of the cows without sub-clinical hypocalcaemia or sub-normal blood glucose levels was higher than that of cows with these conditions (2.5 vs. 2.3 in both criteria, P less than 0.05). It is concluded that postpartum blood calcium concentrations affect the interval from parturition to first service and that the probability of occurrence of hypocalcaemia after parturition can be estimated from prepartum blood calcium concentrations.
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