Question

Which of the following components of milk remains relatively constant during a lactation period
(A). Fat
(B). Protein
(C). Potassium
(D). Lactose
Choose the correct answer from the options given below:

• A. (C) and (D) only.
• B. (B) and (D) only.
• C. (A), and (D) only.
• D. (D) only.

Hint:

Osmotically active components (Lactose and soluble salts like Potassium) are the most stable constituents of milk, as they maintain the blood-milk isotonic barrier.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
The osmotic pressure of milk is kept constant and in equilibrium with blood plasma. This balance is maintained primarily by soluble, low-molecular-weight components.

Step 2: Detailed Explanation:
- Lactose (milk sugar) and soluble minerals like Potassium are the primary osmotic regulators of milk.
- Because the osmotic pressure of milk must remain stable and isotonic with the animal's blood, the concentrations of lactose and potassium are kept within narrow physiological limits throughout the entire lactation cycle.
- In contrast, Fat and Protein are synthesized via complex cellular pathways that are highly sensitive to the lactation stage (extremely high in colostrum, dropping in mid-lactation, and rising again in late-lactation), feeding regimes, and seasonal factors.
Therefore, lactose and potassium remain relatively constant compared to fat and protein.

Step 3: Final Answer
Potassium and Lactose remain relatively constant during lactation.