Retention of H3PO4 and NH4OH by the fibrous components of oat (Avena sativa L.) forage.

Resumen

Objective: To evaluate the structural modification of oat straw through chemical treatment with phosphoric acid (H₃PO₄) and ammonium hydroxide (NH₄OH), focusing on fiber retention and hydrolysis over time, due to its relevance as a forage resource. Design/Methodology/Approach: Oat straw samples (500 g) were treated with 1 M aqueous solutions of H₃PO₄ and NH₄OH separately and exposed for 0, 8, 16, 24, 32, 40, and 48 hours. Samples were not washed prior to analysis to preserve any residual chemical retention on the fiber surface. The following variables were evaluated: neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose, lignin (ADL), silica, and hemicellulose. Data were statistically analyzed using ANOVA and Tukey’s test (p < 0.05). Results: After 8 hours of treatment, H₃PO₄ showed higher retention on structural components, with NDF, ADF, ADL, cellulose, and silica retaining 9.98%, 8.84%, 1.87%, 7.65%, and 2.00%, respectively. In contrast, NH₄OH treatments resulted in lower retention: 4.01% in NDF, 4.84% in ADF, and 4.11% in cellulose. Significant reductions in NDF, ADF, and cellulose content were observed with H₃PO₄ after 16–48 hours, indicating a hydrolytic effect. NH₄OH treatments did not result in significant degradation.

Study Limitations/Implications: The study did not consider the effects of post-treatment washing or neutralization, which could influence the practical application of the treated forage. Nevertheless, the findings highlight the relevance of chemical selection and exposure time in modifying lignocellulosic structures.

Findings/Conclusions: Phosphoric acid (H₃PO₄) exhibited a greater affinity and reactivity with the lignocellulosic matrix of oat straw compared to ammonium hydroxide (NH₄OH), as evidenced by higher initial retention and significant hydrolysis of structural fibers. These results suggest that H₃PO₄ may be a more effective agent for enhancing the nutritional accessibility of oat straw in ruminant diets. Further research is needed to evaluate its practical viability and safety in forage treatment systems.