Effects of calcium supplementation, incomplete milking, and vitamin D

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 D In part 1, the mean ± SD Ca Intramuscular administration of vitamin D