Clinico-Pharmacological Studies of 1,25(OH)_2D_3 to Hypocalcemia in Cows.

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1. In the first study, 1,25-dihydroxyvitamin D_3 [1,25(OH)_2D_3] was injected into late-pregnant cows 12-48 hours prepartum to evaluate the effect of 1,25(OH)_2D_3 for prevention of parturient hypocalcemia. Twelve Holstein cows, at least second parity, were assigned to two groups. Seven cows received 1 μg/kg of 1,25(OH)_2D_3 (1,25(OH)_2D_3 group) in ethanol, and the other five received only ethanol (control group). All cows calved 12-48 hours after administration. Plasma 1,25(OH)_2D_3 concentration in 1,25(OH)_2D_3 group was significantly higher 1 day pre- to 0.5 day postpartum than in control group. Plasma Ca and iP levels in 1,25(OH)_2D_3 group kept high near parturition, and were significantly higher than those in control group from 0.5 day before parturition to 2 days after parturition.In conclusion, it was considered that the intramuscular injection of 1,25(OH)2D3 before 1-2 day(s) of calving had prophylactic effect for parturient hypocalcemia.2. The aim of the second study was to investigate association between occurrence of milk fever and bone metabolism. To observe changes in bone metabolism and associations between it and the development of milk fever, we investigated serum tartrate-resistant acid phosphatase (TRAP) activity at each lactating stage n 83 cows.In this study, it was confirmed utilization of Trap activity in serum for evaluation of bone metabolism in cow. Occurrence of milk fever thought to be related with inactive bone metabolism from the finding of low TRAP activity in milk fever frequent farm. It was thought that measuring of serum TRAP activity was applied to prevent milk fever.