Description
Voluntary dry matter intake (VDMI) and rumen fill were measured on sheep fed with 18 forages ranging from wheat straw to lucerne hay. In vivo fill effect (IVFE i.e. rumen DM pool divided by VDMI), in situ degradability, cell-wall composition, pepsin-cellulase digestibility and in vitro gas production were determined. In situ estimated fill effect (ISFE) was calculated as the retention time of insoluble potential degradable and undegradable fractions using a constant rate of passage. ISFE and IVFE were highly correlated (r2=0.89) but ISFE values were lower than IVFE values because in situ degradability does not integrate comminution time of large particles. NDF content, pepsin-cellulase digestibility and gas production were good predictors of IVFE (r2=0.86, 0.90 and 0.91 respectively) and to a lesser extent of VDMI (r2=0.78, 0.88 and 0.84).
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Ruminal Fill Effect of Forages: Prediction and Relationship with Voluntary Intake
Voluntary dry matter intake (VDMI) and rumen fill were measured on sheep fed with 18 forages ranging from wheat straw to lucerne hay. In vivo fill effect (IVFE i.e. rumen DM pool divided by VDMI), in situ degradability, cell-wall composition, pepsin-cellulase digestibility and in vitro gas production were determined. In situ estimated fill effect (ISFE) was calculated as the retention time of insoluble potential degradable and undegradable fractions using a constant rate of passage. ISFE and IVFE were highly correlated (r2=0.89) but ISFE values were lower than IVFE values because in situ degradability does not integrate comminution time of large particles. NDF content, pepsin-cellulase digestibility and gas production were good predictors of IVFE (r2=0.86, 0.90 and 0.91 respectively) and to a lesser extent of VDMI (r2=0.78, 0.88 and 0.84).
