Ruminal degradability of dry matter and neutral detergent fibre of grasses

Abstract

A study was conducted (I) to determine rumen degradability (in sacco) of dry matter (DM) and neutral detergent fibre (NDF) of the most important grass species grown in the Czech Republic, (II) to compare grass species (n = 5) according to calculated degradation parameters, and (III) to establish prediction equations for degradation parameters from chemical composition. Forty samples of the most important grass species (Dactylis glomerata, Phleum pratense, Lolium perenne, Festuca arundinacea, Felina hybrid) were harvested in 2004 and 2005 and analyzed for chemical composition, and DM and NDF in sacco degradability. Results from the in sacco method were used to calculate DM and NDF degradation parameters. Linear and stepwise multiple regression analyses were used to develop prediction equations for DM and NDF degradation parameters from nutrient concentrations. The highest DM and NDF degradation parameters were found for Lolium perenne. DM and NDF rumen degradation parameters were successfully predicted from chemical composition, with a single predictor adequate for most parameters. For all parameters R<sup>2</sup>-values increased with addition of more predictors into regression equations. Effective degradability (ED) of DM calculated at a rumen outflow rate (k) of 0.05 h<sup>–1</sup> was the best predicted by NDF (R<sup>2</sup> = 0.878), and ED of NDF at k = 0.02 h<sup>–1</sup> by crude protein (CP) (R<sup>2 </sup>= 0.653).