Effects of Wheat Bran, EM Bacteria, Ammonium Nitrate and Fungal Additives on Fermentation and Forage Quality of Rice Straw Silage

Abstract

The global ruminant industry is constrained by a persistent shortage of high-quality roughage, thus rendering the bioconversion of agricultural residues, such as rice straw, a critical priority. Nevertheless, the high lignification, silicification, and nitrogen deficiency of rice straw pose significant biological barriers to traditional ensiling. This study investigated the impact of various additives on rice straw silage quality. Six treatments were evaluated: CK (control, no additives), L1 (200 g/kg wheat bran), L2 (L1 + 1 g/kg EM bacteria), L3 (L2 + 20 g/kg ammonium nitrate), L4 (L3 + 1 g/kg Aspergillus oryzae), and L5 (L4 + 1 g/kg Trichoderma longibrachiatum). All additive concentrations are expressed on a fresh matter basis. After 45 days of ensiling, all treatments significantly improved silage quality compared to the control. Treatments L2-L5 achieved significantly higher sensory scores than CK (P<0.05). All treatments significantly improved silage quality compared to the control, with increased crude protein content, decreased fiber fractions (ADF, NDF), and enhanced Relative Feed Value (RFV) (P<0.05). Fermentation parameters also improved, as evidenced by lower pH values and higher lactic acid concentrations (P<0.05). Results indicate that optimal silage enhancement requires the combined supplementation of fermentable carbohydrates (wheat bran), EM bacteria, and nitrogen source (ammonium nitrate). The addition of A. oryzae further improved silage quality, while the effects of T. longibrachiatum were less conclusive. Treatment L4 achieved the highest Relative Feed Value (RFV: 79.86) and optimal fermentation profile, while L5 showed comparable pH and lactic acid levels but lower RFV (79.29) and acetic acid content. Based on the current experimental conditions, T. longibrachiatum did not provide additional benefits beyond L4 and is not recommended for rice straw silage under these conditions. Overall, treatment L4 produced the most favorable improvements in rice straw silage quality.