This study was carried out to investigate the impact of feeding Barki lambs on straw treated with Trichoderma harzianum and Trichoderma viride fungi on growth performance and protein digestibility. Ten male Barki lambs with an average weight of 26 kg were randomly allocated into two groups of five animals each. Lambs in the first group were fed untreated straw (control). While lambs in the second group were fed straw treated with Trichoderma harzianum (Th) and Trichoderma viride (Tv) fungi (treated group). All experimental animals were fed a concentrated diet and wheat straw at 2 and 1% of their live body weight, respectively, during the feeding trial, which lasted for 90 days. At the end of feeding trial, a digestion trial was carried out on lambs to determine the total digestible nutrients (TDN), digestible crude protein (DCP), and nitrogen balance (NB). The results revealed that treating straw with Th and Tv fungi improved its chemical composition by increasing crude protein and decreasing fiber, and improved the average daily gain, growth rate, TDN, and DCP in male Barki lambs compared to untreated straw.