Thirty-two male fallow deer, half 18- and half 30-month-old, were slaughtered after a 4-month feeding trial on pasture alone or with daily supplement of 500 g (dry matter) concentrate/head (eight each 18- and 30-month-old). The concentrate was composed of 40% maize, 25% sugar beet pulp, 20% alfalfa, 13% soy flakes, 2% minerals and vitamins. Supplemented deer were heavier (49.9 vs 45.0 kg) and their carcasses produced higher dressing proportions (61.5 vs 57.2%) and bigger amounts of first quality cuts. Supplemented feeding improved muscle development and fat deposition. Thirty-month-olds were heavier than 18-month-olds (53.3 vs 41.6 kg) and their carcasses produced higher dressing proportions (60.9 vs 57.7%) and bigger amounts of first quality cuts; older deer carcasses showed better conformation and bigger amounts of fat deposition.