Rumen degradation characteristics of the herbage mass samples and the simulated grazing samples for dairy cows

An experiment was carried out in order to describe the ruminal degradation characteristics of forages, in herbage mass samples (FD) and in simulated g razing samples (FS), obtained at two sward heights (high and low) from a pe rmanent pasture (Lolium perenne L.). The degradation kinetics of the sample s was studied using in situ dacron bags. Data collected were fitted accordi ng to an exponential equation. The soluble fraction (g/kg DM) of the dry ma tter (DM) (299 vs. 351, s.e.d. = 5.4), of the organic matter (OM) (304 vs. 376, s.e.d. = 3.3) and of the nitrogen (250 vs. 301, s.e.d. = 6.4) were sig nificantly higher (P < 0.05) for simulated samples than for the herbage mas s samples. The potential degradability (g/kg DM) of DM, OM and nitrogen was significantly higher on FS compared with the FD (P < 0.05). The effective degradability for the FS samples was greater than for FD samples, either fo r DM (474 vs. 508, s.e.d.= 13.0), OM (490 vs. 529, s.e.d.= 11.6), or nitrog en (351 vs. 419, s.e.d.= 10.0). A significant greater effect (P < 0.05) of the low sward height on the effective degradability was found for the nitro gen only.