Effect of sample pretreatment on alfalfa silage dry matter and protein degradability in sacco

Alfalfa silage was dried and ground (DS) or chopped and frozen (FS) and incubated ruminally in sacco for 1, 2, 4, 6, 8, 12, 24, 30, 36, 48, 54, 60, 72 and 82 h. The water solubility of dry matter (DM) and protein (P) was 27.2 and 50.8% and 25.4 and 66.5%, for DS and FS, respectively. The undegradable fraction and the calculated slope of degradation of DM and P were 27.4% and 0.0134 and 16,9% and 0.0181 for DS, and 28.6% and 0.0131 and 9.6% and 0.0145 for FS, respectively. The data indicate that the methods of sample pretreatment studied have different effects on protein degradation parameters in sacco. Oven drying of alfalfa silage samples causes a decrease in protein solubility and extent of rumen degradation. This effect has to be considered when comparing results from experiments where these processing methods are used.