PROTEIN-DEGRADATION IN RESPONSE TO SPONTANEOUS HEATING IN ALFALFA HAYBY IN-SITU AND FICIN METHODS

Alfalfa forage, field-wilted to 29.9 or 19.7% moisture and packaged in five baling treatments (prestorage control; conventional bales; and l aboratory bales made at 1.0, 1.5, and 2.0 times the density of convent ional bales), was evaluated for protein degradation characteristics by in situ and ficin assays. Relationships between degradation rates and accumulated heating degree days suggested that these degradation rate s are controlled by two conditions. Degradation rates increased concur rently with conservation and minimal heating, primarily because of a l arge redistribution of highly degradable N that was soluble in prestor age controls, but not in conserved hays. For both methods, this effect appeared to be maximized between 100 and 125 heating degree days. Wit h respect to the in situ method, these effects appeared to be less pro nounced, and degradabilities were not affected. After bales accumulate d about 125 heating degree days, degradation rates decreased predictab ly in response to heating by both methods, as did N degradabilities ca lculated from in situ data. Increases in degradation rates concurrent with con servation and minimal heating appear to be especially importa nt considerations when results of the ficin assay are being interprete d.