Vitamin D metabolites in plasma of cows fed a prepartum low-calcium diet for prevention of parturient hypocalcemia.
Our objective was to characterize changes in vitamin D metabolites of plasma in Jersey cows fed a prepartum low-calcium diet. Eight cows were fed a high-calcium diet (80 g/day) and eight were fed a low-calcium diet (8 g/day) at least 14 days before parturition. Calcium concentrations in plasma decreased after initiation of feeding either diet, but cows fed low-calcium diet tended to have lower prepartum calcium and phosphorus and greater peripartal calcium in plasma. Hydroxyproline in plasma was greater during peripartal period in cows fed low-calcium diet. Prepartum 1,25-dihydroxyvitamin D in plasma tended to be greater in cows fed low calcium. Increases in 1,25-dihydroxyvitamin D were only 2 and 3 days after initiation of the low-calcium diet; during the first 2 days after parturition, however, 1,25-dihydroxyvitamin D tended to be lower in those cows fed low calcium. As parturition neared, 24,25-dihydroxyvitamin D tended to be lower in cows fed the low calcium-diet. Usual early postpartum changes in calcium phosphorus, magnesium, 1,25-dihydroxyvitamin D, and hydroxyproline were seen during first few days after initiation of feeding low calcium. Thus, we propose that the preventative action of the low-calcium diet is associated with preparation of the calcium homeostatic mechanism several days before the calcium demand of initiation of lactation.
D000818:Animals; D001847:Bone Diseases / Q000178:diet therapy / Q000517:prevention & control / Q000662:veterinary; D002118:Calcium / Q000097:blood; D002136:Calcium, Dietary / Q000627:therapeutic use*; D002417:Cattle; D002418:Cattle Diseases / Q000178:diet therapy / Q000517:prevention & control*; D004100:Dihydroxycholecalciferols / Q000097:blood*; D005260:Female; D006887:Hydroxycholecalciferols / Q000097:blood*; D006909:Hydroxyproline / Q000097:blood; D006996:Hypocalcemia / Q000178:diet therapy / Q000517:prevention & control / Q000662:veterinary*; D007743:Labor, Obstetric; D007744:Obstetric Labor Complications / Q000517:prevention & control / Q000662:veterinary; D010758:Phosphorus / Q000097:blood; D011247:Pregnancy
D002136:Calcium, Dietary; D004100:Dihydroxycholecalciferols; D006887:Hydroxycholecalciferols; D010758:Phosphorus; D006909:Hydroxyproline; D002118:Calcium