Abstract

Solid-state fermentation represents a strategic biotechnological approach to enhance the nutritional profile of cereal grains for animal feed applications. This investigation systematically evaluated the effects of varying effective microorganism (EM-4) inoculation levels, with and without urea supplementation, on crude protein and crude fiber content in ground yellow maize. A completely randomized design compared five treatments: control (T0), EM-4 alone (T1), and three urea-supplemented EM-4 levels (T2: 25 mL, T3: 35 mL, T4: 45 mL). Fermentation proceeded anaerobically for 72 hours at ambient temperature. Analysis of variance revealed highly significant treatment effects on both nutritional parameters (P < 0.01). Treatment T3 achieved optimal results with 10.51% crude protein (48.0% increase over control) and 2.47% crude fiber (8.9% reduction). Urea supplementation synergistically enhanced protein content through microbial single-cell protein accumulation and non-protein nitrogen conversion, while higher EM-4 levels promoted fiber degradation via cellulolytic enzyme activity. Conversely, lower EM-4 treatments showed preferential utilization of soluble carbohydrates, resulting in apparent fiber elevation. These findings establish intermediate EM-4 dosing with urea as an effective protocol for upgrading maize nutritional quality, offering practical implications for sustainable feed production systems.