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 nitroge n fractions was studied varying the initial straw-treatment moisture l evel (20%, 30% and 40%) and storage temperature (25 degrees C and 35 d egrees C). The urea treatment fundamentally affected the NDF content o f the straw, which decreased as a result of hemicellulose solubilizati on. The decrease in NDF was greatest when the initial temperature and moisture content of the straw were both high, under which conditions t he maximum solubilization of hemicellulose (25%) occurred. In vitro di gestibility and degradability also improved with the urea treatment. I n this regard, the greatest improvement (up to 20 points in the case o f the digestibility results) was seen when hemicellulose solubilizatio n was maximum. The amount of nitrogen retained by the straw (after ded ucting 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. (C) 1998 Else vier Science B.V.