The effect of the forage:concentrate ratio (F:C, %) was studied in a total of 72 dairy ewes (Manchega, MN, n = 36, 70.0 ± 1.3 kg BW; Lacaune, LC, n = 36, 71.5 ± 1.7 kg BW) in early-lactation (65 ± 1 DIM), after the suckling of the lambs. Ewes were sheltered in straw/wood-chips bedded pens of 6 ewes, fed a TMR ad libitum with 0.2 kg/d corn grain at milking, and milked twice-daily in a 2 × 12 parlor with electronic milkmeters (Delaval, Tumba, SE). Experimental design was a factorial 2 × 3 × 2 (breed × diet × duplicate), lasting 8 wk. Dietary treatments were the F:C ratio resulting of adding concentrate (0, 0.5 or 1 kg/d, as fed) to a basal diet (1.8 Mcal NE_L and 15.9% CP, DM basis): high- (HF, 70:30), medium- (MF, 55:45) and low-forage (LF, 40:60). Ewes were fed the HF diet during 4 wk and the experimental diets thereafter (wk 5 to 8). Milk recording was done at each milking and milk sampled on wk 3 and 7 for composition (NIR system; Foss, Nordersted, Denmark). No differences in total DM intake were detected by treatment (MN vs. LC, 2.57 ± 0.19 vs. 3.01 ± 0.19 kg DM/d, on average), but forage intake decreased 28 and 37% with the LF diet, in LC and MN ewes, respectively (P < 0.05). Reduction of forage intake was only detected between HF vs. MF diets in the MN ewes (−21%; P < 0.05). Milk yield varied by breed (MN vs. LC, 1.46 ± 0.09 vs. 2.12 ± 0.22 kg/d; P < 0.001), but no yield nor composition vary by treatment (P = 0.97 to 0.24). Nevertheless, milk fat content decreased numerically between HF and LF diets in both breeds (MN, −8%, P = 0.24; LC, −5%, P = 0.53). No effect was seen between HF and MF diets. Body weight and BCS markedly increased in the LC ewes (HF-MF vs. LF, 2.7 vs. 4.6 kg BW; P = 0.015), but not in the MN ewes. No effect of concentrate was detected on feces consistency, although fecal (P < 0.001) and urinary pH (MN, P = 0.24; LC, P = 0.10) decreased by adding concentrate. In conclusion, the use of high concentrate (>45%, DM basis) had not effect on milk yield and milk composition, producing remarkable BW gains during lactation. On the dairy ewes feeding practice, the final decision on the amount of concentrate to be used will be dependent on the feedstuffs prices and the body reserves of the ewes.