A New Method for Calculating the Gross Value of Proteins

GROSS protein value (G.P.V.) was first described by Heiman et al. (1939) as a numerical expression of the relative response obtained in the growth of chicks when protein supplements are added to a basal diet believed complete in all respects except quality and quantity of protein. The gross value of proteins was obtained graphically by plotting the response due to casein and the response due to the test protein; numerically the gross protein value was equivalent to the amount of casein that would have given the same growth as the test protein consumed, over the amount of the test protein and multiplied by 100. Gross protein value was later calculated by Robertson, Carver and Cook (1940) by expressing the gain per gram of test protein consumed as a percentage of the gain per gram of casein protein consumed. Both the above methods gave values of the growth achieved on the …