A field trial of 1alpha-hydroxycholecalciferol (1alpha-OH D3) in the prevention of milk fever.

The efficacy of 1alpha-OH cholecalciferol for the prevention of milk fever has been tested in a controlled field trial using 597 cows on 19 farms all of which had previously had a high incidence of milk fever. Of 293 cows receiving 1alpha-OH cholecalciferol 34 had milk fever and of 304 control cows 51 had milk fever. Although there was an apparent efficacy of 31 per cent the difference in incidence was not statistically significant. There was no effect if 1alpha-OH cholecalciferol was administered less than 24 hours before the cows succumbed to milk fever. However, if 1alpha-OH cholecalciferol was administered more than 24 hours and less than one week before the occurrence of milk fever the efficacy increased to 61 per cent and the effect was highly significant.