title: Milk fever and dietary cation-anion balance effects on concentration of vitamin D receptor in tissue of periparturient dairy cows.
abstract: Milk fever is the clinical disease associated with severe hypocalcemia in dairy cows. In this experiment, we tested the hypothesis that calcium homeostasis is a result of a decreased concentration of receptors for 1,25-dihydroxyvitamin D in the tissues of cows that develop milk fever. Samples of colon mucosa were obtained for analysis of vitamin D receptor concentration in a longitudinal study of Jersey cows during the 2 wk before and after parturition. In the first study, 21 cows fed an alfalfa hay diet were biopsied every 3rd d from 2 wk before to 2 wk after calving. The concentration of vitamin D receptor in the colon during late gestation was three- to fourfold higher than the concentration of vitamin D receptor in the colon mucosa in nonpregnant cows (90 +/- 8 vs. 26 +/- 5 fmol/mg of protein). At parturition, colon concentration of vitamin D receptor decreased to 66 +/- 7.5 fmol/mg of protein. During early lactation, concentrations of vitamin D receptor in the colon were similar to precalving concentrations. There was no significant difference of concentrations of vitamin D receptor in the colon prior to calving, at calving, or in early lactation between cows that did develop milk fever and those that did not. Results were similar in a second study, in which 7 cows were fed a high cation alfalfa diet, and 6 cows were fed the same diet with anionic salts added. Those data do not support the hypothesis that decreased concentrations of vitamin D receptor prior to calving is a causative factor of milk fever within the Jersey breed. However, a decline of concentrations of vitamin D receptor in tissue at calving may reduce the ability of all cows to respond to the calcium demands of lactation.
authors: USDA, Agricultural Research Service, National Animal Disease Center, Ames, IA 50010-0070, USA.
authors: J P
authors: JP
authors: Goff
authors: T A
authors: TA
authors: Reinhardt
authors: R L
authors: RL
authors: Horst
mesh_terms: D000818:Animals; D000838:Anions; D002117:Calcitriol / Q000378:metabolism; D002412:Cations; D002417:Cattle; D002418:Cattle Diseases / Q000378:metabolism*; D003106:Colon / Q000378:metabolism; D004032:Diet; D005260:Female; D007413:Intestinal Mucosa / Q000378:metabolism; D007743:Labor, Obstetric / Q000378:metabolism; D007774:Lactation / Q000378:metabolism; D010319:Parturient Paresis / Q000378:metabolism*; D011247:Pregnancy; D018167:Receptors, Calcitriol / Q000378:metabolism*
chemical_list: D000838:Anions; D002412:Cations; D018167:Receptors, Calcitriol; D002117:Calcitriol