Eight ruminally cannulated crossbred male sheep (64.5 ± 8.5 kg) were used to evaluate the effect of inclusion of up to 30% crude glycerin, totally replacing corn, on dry matter intake, and DM and NDF in situ rumen degradability of rations. Animals were assigned into a replicated 4 × 4 Latin square design and, in pairs, were fed 1 of the 4 experimental treatments. Diets were composed of corn silage, soybean hulls, soybean meal, mineral premix, and crude glycerin (83% glycerol) replacing 0 (G0), 10 (G10), 20 (G20), or 30% (G30) corn cracked grain (DM basis), in a roughage:concentrate ratio of 40:60. Each experimental period lasted 21 d, composed of 14 d of adaptation and 7 d of data collection. Feed delivered and refused were weighed every morning to assess DMI. The 4 rations incubated in the rumen for 3, 6, 12, 24, 48, 72, and 96 h. The fraction “a” was determined by washing the bags in water and the residue after 96 h incubation was considered the fraction “c.” The potential degradability was calculated with the model: P = a + b (1 - e^kt), and the effective degradability with the model: P = a + b * [k / (k + K_p)]. Treatments tented to promote a quadratic effect in DMI, with increased values observed for G10 and G20 (P = 0.09). Increasing crude glycerin linearly increased fraction “a” of DM and NDF of diets (P < 0.0001), and linearly decreased its fraction “c” (P = 0.004), increasing considerably the effective DM degradability (P < 0.0001). However, degradation rate of DM was unaffected by treatments, while degradation rate of NDF decreased in glycerin treatments (P = 0.01). No effects of crude glycerin was observed in effective degradability of NDF, regardless the passage rate evaluated (2, 5, and 8%/h). The addition of up to 20% crude glycerin seems to improve DMI. This by-product (up to 30% in dry matter basis) is a suitable energetic ingredient to replace corn in diets for sheep since it improves effective degradability of DM without affecting effective degradation of NDF.