Question

What is the appropriate time for injection of Vitamin D3 to prevent occurrence of Milk fever?

• A. One month before calving
• B. 1 week before calving
• C. 2 weeks before calving
• D. 3 weeks before calving

Hint:

Milk Fever Prevention with Vitamin D3: Inject 10 million IU i/m exactly 2--8 days (1 WEEK) BEFORE calving. Never inject too early to prevent PTH suppression.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Parenteral cholecalciferol prophylaxis against periparturient hypocalcemia (milk fever) requires timed administration to peak active 1,25-(OH)2D3 at calving.

Step 2: Detailed Explanation:
Prophylactic protocol for Bovine Milk Fever (Parturient Hypocalcemia) using Vitamin D3:
- A massive single intramuscular injection of Vitamin $\text{D_3$ (Cholecalciferol, $10\text{ million IU}$)} must be administered 2 to 8 days (approximately 1 week) prior to expected calving date.
- This timing allows 3--5 days for hepatic and renal conversion into active $1,25\text{-(OH)}_2\text{D}_3$, ensuring peak stimulation of intestinal calcium absorption and bone resorption exactly at the onset of colostrogenesis at parturition.
- (Giving it $> 10-14$ days before calving leads to refractory suppression of parathyroid glands).

Step 3: Final Answer:
Thus, the appropriate time is 1 week before calving, matching option (B).