Studies on the Productive Value of Roughages and Concentrates for Lactation

Abstract
Four reversal type experiments were conducted with 25 lactating cows to determine the effect of replacing part of a roughage ration with concentrates supplying equal amounts of total digestible nutrients (TDN) or estimated net energy (ENE). TDN proved to be less accurate than ENE for comparing the value of roughages and concentrates for milk production. ENE appeared to slightly overrate the value of roughages in comparison to concentrates for lactation, but to a lesser degree than TDN.