Effects of ensiling on ruminal degradability and intestinal digestibility of Italian rye-grass

Abstract

The effective degradability (ED) and the intestinal effective digestibility (IED) of dry matter (DM) and crude protein (CP) of a green Italian rye-grass (GRG) crop and its silage (ERG) were determined using in situ and particle passage techniques on three wethers, cannulated in rumen and duodenum. Two rumen incubations with duplicate bags filled with 3 g of freeze-dried samples were performed for each feed at times of 0, 2, 4, 8, 16, 24, 48 and 72 h. On each incubation, one series of bags was used to determine rumen degradation and the otherwas freeze-dried and pooled for each incubation time. Then two sub-samples (0.2 g) were incubated into mobile nylon bags through the entire intestine of each animal. The microbial contamination of rumen incubated residues (determined with 15N techniques) was fitted to an exponential function. The asymptotic values (m) for DM contamination showed that silage particle reached a greater colonisation (P=0.006) but with a slower rate of microbe accumulation (P=0.03). Values of m for CP also showed that the undegradable CP fraction was mainly of microbial