A Study of the Crude Fiber and Nitrogen-free Extract Fractions of Orchard Grass Hay and the Digestibility of Some of the Constituents by Milking Cows

Abstract

Digestion trials were conducted with milking dairy cows fed orchard grass hay cut at 4 stages of maturity. A detailed system of analysis that included detns. of the starch, sugars, organic acids, pentosans, alpha cellulose, and lignin was used with these hays and with the corresponding feces to determine the digestion coeffs. of constituents that are ordinarily grouped in the crude fiber and N-free extract fractions. Cellulose isolated from the orchard grass hays cut at 4 stages of maturity and from the corresponding feces contained approx. 25% of furfural-yielding constituents. The apparent digestion coeffs. of the Matrone crude cellulose, corrected Matrone cellulose, alpha cellulose, pentosans, total carbohydrates, organic acids, and undetd. fractions all decreased with advancing maturity of the orchard grass. The similarity in the digestion coeffs. of the alpha cellulose, holocellulose, pentosan, and Matrone crude cellulose fractions indicate that a large part of the forage that is ordinarily included in the crude fiber and N-free extract fractions could be grouped into a holocellulose fraction. A greater percentage of the dry matter of the immature hay was accounted for by the detailed system of analysis than of the more mature hay. Higher percentages of the dry matter were also accounted for in the feces of animals fed immature hay than in the feces from animals fed mature hay. Considerably higher percentages of the dry matter of feces were detd. by the detailed analysis than were detd. by the same analyses on the forage fed to these animals.