TDN Equivalents — Correct Pairs

Which of the following pair(s) regarding TDN equivalents is/are correctly matched?
(a) 1 Kg TDN = 4.4 Mcal of DE
(b) 1 Kg TDN = 0.86 Starch equivalent
(c) 1 Kg TDN = 3.6 Mcal of ME

Correct Answer: All the above

All three conversions are standard and correctly stated:

• 1 Kg TDN = 4.4 Mcal DE: TDN is converted to Digestible Energy (DE) using 4.4 Mcal/kg as the conversion factor. (TDN × 4.4 = DE in Mcal)
• 1 Kg TDN = 0.86 Starch Equivalent (SE): Kellner's starch equivalent is 86% of TDN. SE = TDN × 0.86.
• 1 Kg TDN = 3.6 Mcal ME: Metabolic Energy (ME) = DE × 0.82. So 4.4 × 0.82 = 3.608 ≈ 3.6 Mcal ME/kg TDN.

Additional TDN Facts

• TDN% = DCP% + DCF% + DNFE% + (DEE × 2.25)
• Fat's energy multiplied by 2.25 because fat has 2.25 times more energy than carbohydrate
• 0.32 Kg TDN required by cow per litre of milk produced