Abstract
OBJECTIVE
To evaluate various strategies for prevention of subclinical hypocalcemia (SH) during the first 24 hours after parturition in dairy cows.
ANIMALS
165 multiparous German Holstein cows from 1 herd.
PROCEDURES
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.
RESULTS
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.
CONCLUSIONS AND CLINICAL RELEVANCE
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.
