Use of 24-F-1, 25-Dihydroxyvitamin D3 to Prevent Parturient Paresis in Dairy Cows

Abstract
Forty-one aged Jersey cows were fed a high Ca diet prior to parturition to predispose them to parturient paresis. Twenty-one of the cows were treated with 24-F-1,25-dihydroxyvitamin D3, a synthetic analogue of 1,25-dihydroxyvitamin D3, 7 d before the expected parturition. Treated cows received either 100 .mu.g (n = 7) or 150 .mu.g (n = 14) of 24-F-1,25-dihyeroxyvitamin D3, intramuscularly at 7-d intervals until the cow calved. Incidence of parturient paresis among untreated animals was 85% (17/20). Injections of 100 .mu.g of 24-F-1,25-dihydroxyvitamin D3 reduced the incidence of parturient paresis to 43% 43/7), whereas 150 .mu.g injections of 24-F-1,25-dihydroxyvitamin D3 reduced the incidence of parturient paresis to 29% (4/14). Plasma concentrations of hydroxyproline were not elevated prior to parturition in 24-F-1,25-dihydroxyvitamin D3-treated cows, indicating that treatment did not stimulate bone resorption and that the ability of 24-F-1,25-dihydroxyvitamin D3 to prevent parturient paresis likely resides in its ability to stimulate intestinal Ca absorption prior to parturition. Further, cows treated with 24-F-1,25-dihydroxyvitamin D3 that developed parturient paresis had lower than normal plasma concentrations of 1,25-dihydroxyvitamin D, indicating that 24-F-1,25-dihydroxyvitamin D3 treatment impairs the metabolism of 25-hydroxyvitamin D in response to hypocalcemia. These data suggest that injection of 24-F-1,25-dihydroxyvitamin D3, delivered at 7-d intervals prior to parturition, can effectively reduce incidence of parturient paresis in dairy cows.

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