This experiment carried out in order to determine the ruminal disappearance rate of ten feedstuffs used in ruminant diet and to determine the best ruminal digestive model using mobile nylon bag technique. Feedstuffs were corn grain, barley grain, corn silage, alfalfa hay, whole barley hay, cotton seed meal, soybean meal, meat meal, fish meal and wheat bran. The nylon bags containing each feedstuff were in duplicate for 0,2,4,8,12,24,48 and 96 h in three steers fitted with rumen fistula. In order to determine the disappearance rates in 0 h , samples were washed by cold water. Disappearance rates of dry matter and crude protein determined by calculating of rate of their weight loss. Using completely randomized design the statistical comparing of disappearance rates of dry matter and crude protein of feedstuffs in three studied groups (energy, protein and forage sources) carried out. Disappearance rates of dry matter and crude protein in 0 h in each of the three sources had significantly differences(p<0.05) and disappearance rate of dry matter and crude protein of feedstuffs in 96 h in each of protein and forage sources had significantly differences but in energy sources had not significantly differences. The best ruminal model for determining disappearance rate constants of dry matter and crudeprotein of feedstuffs was: IR (t) =Di. exp(-kd.t)+ I0 which IR (t),Di, kd,t and I0 were insoluble residue at any time t ,potentially digestible fraction at any time disappearance rate constant, time and indigestible residue respectively. Dry matter fractional rate constant of digestion (kd) in ruminal digestive models for corn grain, barley grain, corn silage, alfalfa hay, barley hay, cottonseed meal, meat meal, fish meal, wheat bran and soybean meal were :4, 15,6,9,15,26,32, 10,4 and 5.9 % / h respectively, and indigestible fraction (residue) of dry matter were: 25, 183, 364, 401, 6/341, 633, 608, 208.3, 450 and 133 g.kg-1 respectively. Crude protein fractional rate constants of digestion (kd) in ruminal digestive models for corn grain, barley grain, corn silage, alfalfa hay, barley hay, cottonseed meal, meat meal, fish meal , wheat bran and soybean meal were: 0.2, 17,0.4, 14, 18,24,35, 14,69 and 2.8 % / h respectively, and indigestible fraction (residue) of crude protein were: 0,30.02,0,69.6, 13.2,266.5, 435,37.92, 103.15 and 69.72 mg, respectively.