The in sacco degradation of crude protein and cell wall constituents in grass, alfalfa and maize silages.

Abstract

Degradation of crude protein (CP) and cell wall constituents (CWC) in grass, lucerne and maize silages were estimated after incubation for 48 h in nylon bags in the rumen of 2 Dutch Friesian cows fed daily on hay 10 kg and concentrates 1 kg. Estimation of fractional rates of degradation was based on a single exponential degradation model. Fractional degradation rates of CP in grass, lucerne and maize silages were 5.2, 5.0 and 6.3% per h respectively. Corresponding values for CWC were 4.3, 4.0 and 2.8% per h. The non-degradable CWC fraction was higher in lucerne silage (52.1%) than in grass and miaze silages (20.4 and 24.6%, respectively). Extent of degradation of lucerne CWC was lower than that of maize and grass silages but voluntary intake of lucerne silage by steers was higher. Voluntary intake of silages cannot be explained by content, composition and degradation of CWC only; the physical structure may also be involved. (Abstract retrieved from CAB Abstracts by CABI’s permission)