Relationship Between Measurements of Heating and Acid-Detergent Insoluble Nitrogen in Heat Damaged Fresh Alfalfa, Haylage, and Hay

Abstract

During five laboratory trials, alfalfa fresh (25% dry matter), haylage (42% dry matter), and hay (89% dry matter) were heated to 88 C for 48 h at five rates (140, 5.8, 2.9, and 1.5 C/h). Percent total nitrogen converted into acid-detergent insoluble nitrogen was 46.5, 38, and 27 for these forages heated at 140 C/h for 48 h. During the first 6 h of heating, acid-detergent insoluble nitrogen in haylage was increased 4 to 9 fold more rapidly than that in fresh alfalfa or hay. Among the 10 measurements of heating, none produced squared correlation coefficients larger than .25 with total nitrogen. Measurements of hours heated above 70 C, degree-hours above 50 or 60 explained 69 to 73% of the variation in acid-detergent insoluble nitrogen as a percent of dry matter or total nitrogen. Measuring maximum temperature alone gave relatively low (less than .5) coefficient of determination for acid-detergent insoluble nitrogen fraction. © 1976, American Dairy Science Association. All rights reserved.