Step 1: Understanding the Concept:
Colostrum is the "first milk" produced by the mammary glands of mammals (like cows and buffaloes) immediately after giving birth.
It is fundamentally different from regular milk; it is highly concentrated, yellow in color, and extremely rich in immunoglobulins (antibodies), proteins, minerals, and vitamins (especially Vitamin A).
Because calves are born with "epitheliochorial" placentation, maternal antibodies do not cross the placenta. Consequently, the calf is born without any immune protection and must acquire "Passive Immunity" by consuming colostrum.
Step 2: Detailed Explanation:
The feeding of colostrum involves two critical dimensions: Timing and Quantity.
Timing: The calf's small intestine is capable of absorbing large immunoglobulin molecules only during the first 24 hours of life. The efficiency of this absorption drops significantly after 6 hours and virtually stops (gut closure) after 24 hours. Therefore, the first feeding should occur within 1-2 hours of birth.
Quantity: The standard recommendation in dairy management is that a calf should consume colostrum equivalent to approximately 10% of its body weight during the first 24 hours.
For instance, if a newborn calf weighs 35 kg, it should receive approximately 3.5 liters (or kg) of colostrum.
This quantity ensures that the calf receives a sufficient mass of IgG (immunoglobulins) to achieve a serum IgG concentration of $> 10$ mg/mL, which is necessary to prevent "Failure of Passive Transfer" (FPT).
Evaluation of other options:
Options (A) \( 25% \), (B) \( 30% \), and (D) \( 40% \) are excessively high. Overfeeding can lead to abomasal bloat or severe nutritional scours (diarrhea), as the calf's digestive system cannot process such large volumes at once.
Step 3: Final Answer:
Scientifically validated management practices dictate that a newborn calf must be fed colostrum at the rate of 10% of its birth weight within the first day of life.
Hence, the correct answer is option (C).