An experiment was conducted with the objective of replacing vetch for concentrate mix on feed intake and digestibility as well as milk production and composition in lactating F1 crossbred (Boran x Friesian) cows fed with a basal diet of urea-molasses-treated wheat straw. Eight crossbred cows of similar milk yield (8–10 kg d-1), body weight (BW) and stage of lactation (early lactation), but differing in parities were arranged in 4 x 4 double Latin square design. The treatments included offering urea-molasses treated wheat straw (UMTWS) ad libitum and supplementation with concentrate mix (T1), and replacement of the concentrate mix with vetch (Vicia dasycarpa) hay at a level of 25% (T2), 50% (T3) and 75% (T4). The concentrate mix consisted of 74% wheat bran, 25% noug seed (Guizotia abyssinica) cake and 1% common salt. In sacco degradability study showed that the concentrate mix and vetch were similar in rumen degradability parameters, except that rate of degradation was relatively faster for vetch hay. Total dry matter (DM) intake was significantly higher (P<0.05) for cows in T3 compared to cows in the other treatments. Nutrient intakes and apparent digestibility were non-significant (P>0.05) among treatments, except for cows in T3 that had higher (P<0.05) acid detergent fibre (ADF) intakes than cows on T1 and T2. Crude protein (CP) and metabolisable energy (ME) intakes were sufficient to meet daily requirements for the observed mean daily milk yield of 6.5 kg. Cows in T1 produced higher (P<0.05) milk yield compared to cows in T4. Milk compositions were similar (P>0.05) for cows in the different treatments. It is concluded that vetch hay could substitute up to 50% of the concentrate mix without compromising feed intake and digestibility of nutrients as well as milk yield and compositions of lactating F1 Boran x Friesian cows.