TDN Requirement per Litre of Milk

TDN required by cow for 1 liter of milk production is:

Correct Answer: 0.32 kg TDN

A dairy cow requires 0.32 kg of TDN (Total Digestible Nutrients) for the production of 1 liter of milk. This is the production allowance over and above the maintenance requirement.

What is TDN?

TDN is a measure of the energy value of a feed — it is the sum of digestible crude protein, digestible crude fiber, digestible nitrogen-free extract, and 2.25 × digestible ether extract. It represents the total digestible portion of a feed that provides energy.

Key Nutrient Requirements of Dairy Cows

• Maintenance TDN: based on body weight of the cow.
• Production allowance: 0.32 kg TDN per litre of milk.
• Milk fat synthesis: Acetate (a VFA produced in the rumen) is the primary precursor for milk fat synthesis.

Why Other Options Are Wrong

• 0.45 kg → overestimate for production requirement.
• 0.50 kg → too high; this would be excessive.
• 0.55 kg → even higher; well above the standard production allowance.