BIOECONOMIC VALORIZATION OF Bactris Gasipaes Kunth SHELLS AS A SUBSTRATE FOR SHIITAKE MUSHROOMS AND ITS BYPRODUCT FOR BEEF CATTLE FEED

Bactris gasipaes Kunth (peach palm) processing generates byproducts (shells), which when inappropriately discarded, cause environmental problems. These shells are lignocellulosic material with great potential as a substrate for the axenic cultivation of mushrooms. Nevertheless, after the mushroom harvesting, there is a byproduct (spent mushroom substrate; SMS), which presents high nutritional value. This study aimed to verify the technical viability of Shiitake (Lentinula edodes) production in an axenic cultivation system using peach palm shells as substrate and to evaluate the SMS as an ingredient for beef cattle diet. Shiitake mushrooms in axenic cultivation was carried out using supplemented (20%; manioc bagasse, soya bran, and sorghum flour; 5 treatments) external shells as substrate (80%) to evaluate the substrate influence on productive parameters and chemical composition, mainly total protein and β-glucans content. The SMS that presented the highest β-glucans content was analyzed using an in vitro system to assess the effects on ruminal fermentation and greenhouse gas parameters. Results showed that all treatments of the axenic system presented mushroom growth. Treatment 2 (supplemented with soya bran and sorghum flour) obtained the highest total number of mushrooms (6 mushrooms) and protein content (27.03%), while treatment 4 (supplemented with soya bran and manioc bagasse) presented the highest mushroom wet weight, performance, and biological efficiency (97.28 g, 19.45%, and 67.06%, respectively), and 3 (supplemented with manioc bagasse and sorghum flour) had the highest β-glucans content (mushrooms: 29.53%; SMS: 11.27%). The SMS presented similar digestibility (73.95%) to conventional diets (corn silage and sugar cane) and lower methane and carbon dioxide emissions than corn silage (22% lower and 21.3% lower, respectively) and sugar cane (20.9% lower and 22.6% lower, respectively). This study highlighted a sustainable use of byproducts for human and cattle diets, promising for digestibility, nutritional value, β-glucans incorporation, and environmental impact mitigation, favoring the circular bioeconomy.