Relationship between dry matter, fibre and nitrogen degradation characteristics of silage and silage intake of steers

A study was carried our to examine the relationship between silage intake a nd rumen degradability characteristics of silage. The dry matter (DM), neut ral-detergent fibre (NDF), acid-detergent fibre (ADF), hemicellulose and,ni trogen (N) degradability characteristics of 136 silages were determined usi ng polyester bags in three rumen fisfulated beef cross steers. The bags wer e incubated for 0, 6, 22, 24, 48 and 72 h. Intakes of these silages, by ste ers, were reported by Steen et al., 1998. The relationships between silage DM intake (g/kg metabolic live weight) and DM,fibre and N degradability cha racteristics of the silages were poor (R-2 < 0.32). Degradability character istics of the silages were highly negatively correlated with fibre concentr ation of the silages (R < -0.82) and highly positively correlated with the soluble N minus ammonia concentration (R < 0.77). Some of the degradability characteristics were highly correlated with organic matter digestibility, particularly the proportion of DM, fibre and N degraded after 72 h (R = 0.7 5 to 0.85). lit view of the poor relationship between silage intake and deg radability, the results of this study question the role of degradation char acteristics of DM, fibre and N in the rumen on silage intake.