Effects of calcium supplementation, incomplete milking, and vitamin D3 injection on serum total calcium concentration during the first 24 hours after parturition in dairy cows fed an anionic diet during late gestation.

Abstract

To evaluate various strategies for prevention of subclinical hypocalcemia (SH) during the first 24 hours after parturition in dairy cows. 165 multiparous German Holstein cows from 1 herd. All cows were fed a ration with a moderate dietary cation-anion difference (approx 0 mEq/100 g of dry matter; anionic diet) for the last 2 to 3 weeks of gestation. In the first part of a 2-part study, cows were randomly assigned to 1 of 4 treatment groups (no calcium supplementation [n = 30], oral administration of a calcium bolus alone [34] or in combination with IV administration of 500 mL of a calcium solution [34] or incomplete milking during the first 24 hours after parturition [34]). In part 2, cows in their fifth or greater parity were randomly assigned to receive vitamin D3 (20,000 U/kg, IM; n = 15) 7 days before the predicted calving date or a control group (18). A calcium bolus was orally administered within 30 minutes after parturition to all cows of part 2. Serum total calcium (Cat) concentration was measured immediately after parturition and every 2 hours thereafter for 24 hours and compared among treatment groups. Subclinical hypocalcemia was defined as a Cat concentration < 2.00 mmol/L. In part 1, the mean ± SD Cat concentration during the 24 hours after parturition for the IV-treated group (2.28 ± 0.42 mmol/L) was greater than that for the other 3 groups, each of which had a mean Cat concentration < 2.00 mmol/L. In part 2, the mean Cat concentration for the vitamin D3-treated cows was greater than that for control cows and remained above 2.00 mmol/L for the duration of the observation period. Intramuscular administration of vitamin D3 or IV administration of a calcium solution in combination with oral administration of a calcium bolus might alleviate SH during the first 24 hours after parturition in dairy cows fed an anionic diet during late gestation.