Question

What of the followings could be called as 'True growth' of calf when fed on milk

• A. 1 kg BW gain/ 1.09 kg DM of milk
• B. 1 kg BW gain/ 1.39 kg DM of milk
• C. 1 kg BW gain/ 1.59 kg DM of milk
• D. 1 kg BW gain/ 1.79 kg DM of milk

Hint:

Remember that pre-ruminant calves have a highly efficient digestive system for milk because of the esophageal groove, which bypasses the undeveloped rumen and channels milk directly into the abomasum for enzyme digestion.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
For newborn pre-ruminant calves, whole milk is highly digestible, containing highly bioavailable proteins, fats, minerals, and vitamins. The feed conversion ratio (FCR) of milk dry matter (DM) to body weight (BW) gain is extremely high compared to solid feed or grain.

Step 2: Detailed Explanation:
Let us analyze the relationship between milk dry matter intake and body weight gain in young calves:

Whole cow milk contains approximately 12% to 13% dry matter (DM) and has a digestion coefficient of nearly 95% to 98% in the pre-ruminant digestive tract.

During the first few weeks of life, a calf's growth is characterized primarily by deposition of protein and water in muscle tissue (skeletal muscle growth), rather than fat storage. This is defined physiologically as "true growth."

Because of the high nutrient density and digestibility of milk, the efficiency of converting milk dry matter into body tissue is extremely high.

Under optimal feeding conditions, a pre-ruminant calf can achieve1 kg of body weight (BW) gain for every 1.09 kg of milk dry matter (DM) consumed.

As the calf grows and starts consuming starter feed and roughage (which are less digestible), the FCR increases (meaning more dry matter is needed per unit of gain).
Thus, 1 kg BW gain per 1.09 kg DM of milk is the standard value representing true growth on a milk diet.

Step 3: Final Answer:
The correct option is (A).