Predicting Degradation Characteristics from Chemical Composition and Soluble Fraction of Poor Quality Roughage Diets

This study was conducted to explore the feasibility of predicting quality from selected chemical and degradability measurements for two browses (Alchornea cordifolia (A), Ficus coapensis (F), and two crop residues (maize (M) and rice stover (R.) and their mixtures; Degradation characteristics were determined in the rumen of three West African Dwarf (WAD) goats, three WAD sheep and three White Fulani steers. Each animal was fitted with a permanent ruminal canulae, and was routinely fed on Panicum maximum and equal amount officus and alchornea at a ratio of 70:30 respectively (dry matter basis). The DM disappearance values were fitted to the exponential equation P = a + b (l-e*1) where P is amount degraded at time (t) as the soluble fraction, b is the potentially degraded fraction, and c is the rate at which b degrades. Effective degradability (ED) was also determined. The ED of the feeds and their mixtures varied from 256 to 373 (g/kg). The experimentally determined values were compared, to calculate values based on predictions from individual chemical components (separately or combined) with the inclusion of the soluble fractions in the regression analyses. The use of the individual chemical components (NDF, ADF, cellulose, and lignin) was not effective in predicting the degradation characteristics. When the chemical components (cellulose, hemicellulose, lignin and total nitrogen) were combined in a multiple regression analysis, prediction was also poor. However, the results suggest that cellulose and lignin contribute significantly to the prediction. The inclusion of the washing loss in the multiple regression analysis with the combined chemical components improved the prediction of ED. Calculated ED values from predictions correlated well with the experimentally determined ED. The coefficient of correlation between the observed and calculated ED values was highest for cattle (0.95) followed by sheep (0.93) and goats (0.77).