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

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Abstract
During 5 laboratory trials, alfalfa fresh (25% dry matter), haylage (42% dry matter) and hay (89% dry matter) were heated to 88.degree. C in .5, 12, 24, 36 and 48 h for trials 1, 2, 3, 4 and 5, respecively. Total heating time of each trial was 48 h. Percent total N converted into acid-detergent insoluble N was 46.5, 38 and 27% for these forages heated at 140.degree. C/h for 48 h. During the first 6 h of heating, acid-detergent insoluble N 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 N. Measurements of hours heated above 70.degree. C, degree-hours above 50 or 60 explained 69-73% of the variation in acid-detergent insoluble N as a percent of dry matter or total N. Measuring maximum temperature alone gave a relatively low (less than .5) coefficient of determination for an acid-detergent insoluble N fraction.