Degradability of Forages in Sacco

Rumen degradabilities of meadow grasses and silages of the same grasses were observed by incubation in sacco for 2, 6, 24 and 48 h. Samples of crops and silages were oven dried (70°C) and freeze dried (-60°C). Grass crops lost more dry matter (DM) and organic matter (DM) than silages, while silages showed the greater losses of N at 2 and 6 h incubation. Rate constants of losses, obtained by non linear regression, ranged higher for crops than silages. DM losses exceeded OM losses, but gradually less by extended incubation. Freeze drying resulted in greater losses than oven drying, yet mainly until 12 h incubation. The effect of drying method was greater on silages than crops, but initial losses of N was more depressed by oven drying of crops than silages. Efective protein degradability (EPD) ranked higher for silages than crops and higher for freeze dried oven dried samples. Increasing outflow rate from the rumen would decreased EPD to a greater degree for grass crops than silages.