There were investigated the effect of feeding lambs green fodder and the effect of breed origin of lambs on the basic chemical composition and physicochemical features of longissimus dorsi muscle. Ram lambs (50% derived from the prolific line of Kołudzka sheep and 50 % of F1 hybrids after the Ile de France meat rams) were intensively fattened up to body weights from 32 to 37 kg, in 3 groups. The animals were fed ad libitum and received the same nutritive fodder, although with various amounts of roughages added (grass hay, green forage, pasture grazing). The feeding methods applied and the commercial crossing pattern affected the intramuscular fattening of meat. A significantly more fattened meat was obtained from lambs, which temporarily grazed on a pasture compared to meat of lambs fattened in aźsheep barn with grass hay or green fodder (from field cultures) added, as well as from lambs of the prolific Kołudzka sheep compared to the meat of hybrids after the Ile de France meat rams. No significant differences were found in the size of natural drip, water holding capacity, and muscle tissue weight losses during cooking, i.e. there were no differences that could depend either on the feeding system applied or on the breed origin of experimental lambs. No clear effect of the feeding factor was found on pH and electrical conductivity of the lamb muscle tissue, although there was a significantly higher pH and a tendency toward a lower electrical conductivity in the longissimus dorsi muscle in hybrids compared to the Kołudzka lambs. A clearer and, partially, statistically confirmed effect of feeding lambs being fattened fodder supplemented with green forage was found with regard to the colour, marbling and tenderness of meat. The crossing of the Kołudzka sheep and of the Ile de France rams did not impact the colour of meat, although a tendency was found toward a lower marbling of meat and toward the decrease in the tenderness of meat compared to the meat of lambs of the initial line.