Step 1: Understanding the Concept:
A bull is used for breeding.
The number of bulls needed depends on the herd size.
Step 2: Key Formula or Approach:
No specific formula.
Need to know the recommended bull to female ratio.
Step 3: Detailed Explanation:
A bull can serve a certain number of females.
Generally, one bull is maintained for about 5% of the breedable female stock.
This means approximately 1 bull per 20 females.
Thus, the correct percentage is 5%.
Step 4: Final Answer:
The number of bulls to be maintained is 5% of breedable female stock.
Hence, the correct option is (A).