Step 1: Understanding the Concept:
Milk fever (parturient paresis) is a calcium metabolism disorder.
It occurs around calving time.
Step 2: Key Formula or Approach:
No specific formula.
Need to understand the prevention of milk fever.
Step 3: Detailed Explanation:
Cows and ewes are kept on a low calcium diet late in pregnancy.
This stimulates the body to mobilize calcium from bones.
It prevents milk fever at calving.
Thus, low calcium feed prevents milk fever.
Step 4: Final Answer:
Low calcium feed late in pregnancy prevents milk fever.
Hence, the correct option is (A).