The dynamic interactions within the rumen are difficult to simulate. In situ technique allow us to study digestion within the rumen and reduce the need for ruminal simulation. The nylon bag technique has been used for many years to provide estimates of both the rate and extent of disappearance of feed constituents (Mehrez and Ørskov, 1977).This technique provides a useful means to estimate rates of disappearance and potential degradability of feedstuffs and feed constituents. The technique has also provided relatively good predictions of forage intake and digestibility (Ørskov, et al., 2000) and has greatly improved the understanding of nitrogen (N) supply to ruminants and their microbes. By-product feeds are produced by the wet milling, brewing, and other food or feed processing industries and have been recognized as potential feed sources for decades. Feeding by-products to dairy cows and other livestock will probably continue to increase in the future. By-product feeds fed to dairy cows and other livestock prevents a waste disposal problem for industry and reduces the amount of concentrate that must be included in the diet to ensure maximum animal performance. The object of this study was to evaluate of nutritive value of grape marc (GM), noodle waste (NW), tomato pomace (TP), apple pomace (AP), grape pomace (GP) and raisin waste (RW) using nylon bag technique.