ANN 121: Applied Animal Nutrition-I (2+1)

 PROTEIN REQUIREMENT FOR GROWTH 

Factorial method

• The amount of protein required for maintenance is determined first.
• The value thus obtained is added to the amount of protein required for growth (or say gain in weight) plus losses in metabolism.
• The maintenance needs can be determined directly on the basis of endogenous urinary nitrogen or calculated from the basal energy metabolism and later corrected for metabolic faecal nitrogen losses. The amount required for the growth tissue formed can be estimated from the slaughter data.

Nitrogen balance studies

• It is an exact measure of actual requirement of protein.
• Calves are raised on equal amounts of dry matter and on isocaloric rations which contain different levels of protein and the minimum intake of protein which provides maximum retention is taken as the estimate of requirement.

Based on feeding trials

• The rations containing different levels of protein are fed to determine the minimum level required to give the maximum rate of growth.
• The nature of growth thus obtained may be further tested by slaughter tests for assessing the integrity of the nitrogenous tissues.