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

Abstract

Because of its importance as fodder, the treatment of oat straw with phosphoric acid (H₃PO₄) and ammonium hydroxide (NH₄OH) was studied. Five hundred g of oat straw were sprayed separately with 1 molar aqueous solutions of these chemical compounds and after 0, 8, 16, 24, 24, 32, 40 and 48 hours, without washing, samples were taken for analysis. The response variables determined were neutral detergent fiber (NDF), acid detergent fiber (ADF), cellulose, lignin (LDA), silica and hemicellulose. The effects of chemical compounds (analysis of variance, p<0.05) and time (Tukey, p<0.05) were evaluated. Using all data, Hem was higher with H₃PO₄, while FDA, ADL, cellulose and silica were higher with NH₄OH. Overall, most response variables with H₃PO₄ and only NDF, FDA and cellulose with NH4OH were greater (retention effect) at 8 hours than at 0 hours of treatment. From 16 to 48 hours with H₃PO₄, FDN, FDA and cellulose decreased (hydrolytic effect) and no variable did so with NH₄OH. During 8 hours of treatment, FDN, FDA, LDA, cellulose and silica retained 9.98, 8.84, 1.87, 7.65 and 2.00% of H₃PO₄, respectively, while FDN, FDA and cellulose retained 4.01, 4.84 and 4.11% of NH₄OH, respectively. Additionally, at 48 hours of treatment, a hydrolytic effect was observed with H₃PO₄. In conclusion, NDF retained more H₃PO₄ than NH₄OH and in turn was more hydrolyzed by the former than by the latter.