Comparison of the in situ degradation parameters of fresh and frozen-thawed 15N-labelled alfalfa and ryegrass

Degradation of dry matter (DM) and nitrogen (N) in fresh or frozen-thawed alfalfa and ryegrass was studied by using in situ technique. The forages were labeled with 15N during growth in a glasshouse, harvested at similar growth phase, and fresh (F) or frozen-thawed (FT) samples were incubated in the rumen of 3 sheep. There was no difference (P> 0.05) between forage type (S) for the immediately soluble fraction (a) and the insoluble but slowly degradable fraction (b) estimates for DM and N disappearance over time. However, 15N values for a and b were significantly (Pb (c) and potential degradability of DM, N and 15N; degradation rate of b for DM, N and 15N were higher for alfalfa. There was no effect due to sample preparation (M) in degradation rate (c) for DM and 15N but FT had a significantly (P15N. Mean estimates of effective rumen degradable protein due to forage species were significantly (Pin situ degradation determination the same preparation method be used throughout.

Comparison of the in situ degradation parameters of fresh and frozen-thawed 15N-labelled alfalfa and ryegrass Keywords:

fresh forages , in situ , degradation , dry matter , nitrogen , labeled nitrogen