Twenty multiparous Friesian cows, 80 to 130 days postpartum, were allotted to two groups of 10 cows, according to calving date, lactation number, and daily milk production, and assigned randomly to one of two diets in a crossover design experiment. The control diet was 53% maize silage (dry basis) and contained ground maize, soya bean meal and wheat bran in proportions to ensure that the dietary dry matter contained 16% crude protein, 11.5 MJ metabolizable energy/kg DM and 15% crude fibre. The treatment diet contained ensiled wet tomato pomace at 13% (dry basis) replacing maize silage and soya bean meal. The two diets contained similar quantities of crude protein, metabolizable energy, and crude fibre. The diets were offered individually, in tie-stalls, as total mixed rations in two equal proportions for ad libitum intakes. The cows were allowed exercise in an open lot without shade. Dry matter, metabolizable energy and crude protein intakes, actual milk production, milk composition and body condition score were not affected by the diet. In contrast, supplementation with ensiled wet tomato pomace decreased 4% fat-corrected milk production (22.2 vs. 20.2 kg/day; P < 0.05). No differences were observed in blood plasma concentrations of glucose, total protein, urea, triglycerides, cholesterol, phospholipids, Na, K, Ca, P, and Mg.