Effect of vitamin D source and amount on vitamin D status and response to endotoxin challenge.

The objectives were to test the effects of dietary vitamin D [cholecalciferol (CHOL)] compared with 25-hydroxyvitamin D [calcidiol (CAL)] on vitamin D status and response to an endotoxin challenge. Forty-five Holstein bull calves (5 ± 2 d of age) were blocked into weekly cohorts, fed a basal diet that provided 0.25 µg/kg body weight (BW) CHOL, and assigned randomly to 1 of 5 treatments: control [(CON) no additional vitamin D], 1.