Abstract: Four Barbarine breed sheep (initial average BW and age 58 kg and 18 month, respectively), receiving a basal diet composed of oat hay, were used in a Latin square design (4�4) to study the effect of the total substitution of soybean meal (D1: Sb: 23.5% of concentrate) by corn distillers dried grains with soluble (D2: DDGS: 45%) or corn gluten feed (D3: CGF: 65%) or a mixture of the 2 ingredients (D4: CGF+DDGS, respectively 23 and 26%) on intake, digestibility and nitrogen balance. The proportion of concentrate in diet was adjusted at a level of 25% of the total dry matter intake. Each experimental period lasted 28 days (21 and 7 days, respectively for adaptation and measurements). The compound feeds were approximatively iso-nitrogenous and iso-energetic. The obtained results showed that the studied corn co-products were characterized by a high quality of crude protein. The voluntary intake of hay and total diet DM were not affected by the applied substitution (average value 53.2 g DMkg-0.75 day-1). No effect of substitution was noted on DM, OM and CP digestibility or N balance. In contrast, an improvement of the digestibility of crude fiber was observed (p<0.05), mainly in diet containing DDGS. The biological quality of N expressed as the ratio: Retained N/Absorbed N, seamed to be higher in SBM, DDGS and GDDS diets (averaged 30.5%) than in CGF one (26.6%). It was concluded that substituting soybean with corn co-products in concentrate supplied at a rate of 25% of DM total intake did not affect nutritive value of oat hay based ration and the studied diets were nutritionally similar.