The Effects of Oyster Mushroom Stem Waste Dietary Supplementation on Growth Performance, Meat Quality Parameters, and Antioxidant Capacity in Lambs

Oyster mushroom cultivation results in the generation of large amounts of by-products, the improper disposal of which can have adverse environmental consequences. The utilization of mushroom stem waste as a functional feed ingredient could serve as a promising strategy for its sustainable management and the development of alternative feed resources. This experiment investigates the effects of dietary enrichment with dried oyster mushroom stem waste of the Pleurotus ostreatus species (OMSW) on lamb growth performance and meat quality indices. Twenty-four 3-month-old male Chios lambs were randomly assigned to three groups; a control group (C) that received a basal diet; the P2 group that was offered a concentrate supplemented with 2% dried OMSW; and the P4 group, supplemented with 4% OMSW. Individual feed intake and body weight measurements were recorded weekly during the 28-day experimental period for each lamb. At the end of the feeding trial, lambs were fasted for 12 h and slaughtered. The internal organs (spleen, kidneys, liver, lungs, and heart) were then weighed, along with the hot carcass for each lamb. After 24 h at refrigerated storage, cold carcass weight was recorded and samples of longissimus thoracis muscle were collected from each lamb for subsequent meat quality assessment. No significant differences were observed among the three groups in feed intake and body weight throughout the experiment. Hot and cold carcass and internal organs’ weights were also not affected by OMSW addition. Moreover, meat quality characteristics, such as pH, color, water holding capacity, shear force values and intramuscular fat were similar among the experimental groups. Meat oxidative stability during refrigerated storage was ameliorated (p = 0.002), possibly due to the antioxidant activity exerted by the phenolic compounds contained in OMSW, without any adverse effects on the meat fatty acid profile. These findings indicate that OMSW may be successfully incorporated into growing lamb diets up to 4% as an alternative feed without adverse effects on intake, production or meat quality.