Effect of substituting soybean meal with mycelium of Penicillium chrysogenum in lamb diets on performance and carcass quality

Thirty-two intact male Pelibuey lambs with an average weight of 21.2 kg were randomly assigned to four treatment rations in a completely random design. The four experimental rations contained incremental levels of dry waste mycelium: 0, 2.7, 5.4 and 8.1%. The study was 75 days long, with 15 days for adaptation of lambs to their pens and a 60-day experimental period in which dry matter (DM) intake, daily weight gain, and feed efficiency were determined. At the end of the study, lambs were slaughtered, and their carcasses weighed and marbling scores determined. Results show a quadratic effect on DM intake (P = 0.035) and ADG (P = 0.006). Both DM intake and ADG first increased before declining as mycelium level increased in the diet. Gain:feed decreased linearly (P < 0.001) with an increase in waste mycelium in the diet. Carcass characteristics, such as hot and chilled carcass weight and hot and chilled dressing percent, and carcass marbling score, were not affected (P > 0.10). Marbling score of the carcasses ranged from traces to modest marbling.