Effect of moisture and temperature on the degradability of fiber and on nitrogen fractions in barley straw treated with urea

The effect of the treatment of barley straw with urea (6% of the D.M.) on its chemical composition, digestibility, degradability and nitrogen fractions was studied varying the initial straw-treatment moisture level (20%, 30% and 40%) and storage temperature (25°C and 35°C). The urea treatment fundamentally affected the NDF content of the straw, which decreased as a result of hemicellulose solubilization. The decrease in NDF was greatest when the initial temperature and moisture content of the straw were both high, under which conditions the maximum solubilization of hemicellulose (25%) occurred. In vitro digestibility and degradability also improved with the urea treatment. In this regard, the greatest improvement (up to 20 points in the case of the digestibility results) was seen when hemicellulose solubilization was maximum. The amount of nitrogen retained by the straw (after deducting the residual urea) rose under conditions of increased moisture and temperature, reaching its highest values at moisture levels of 35% and 40%, when the best urea hydrolysis also took place.