Nitrogen Flow to Duodenum of Steers Grazing on Orchardgrass and Meadowfescue Pastures

This experiment was conducted to evaluate nitrogen flow to the duodenum of steers grazing on orchardgrass (Dactylis glomerata L., OG) or meadowfescue (Festuca elatior L., MF) pasture. Holstein steers fitted with cannulas in the rumen and duodenum were used. Nitrogen content and in vitro dry matter digestibility of herbage did not differ between OG and MF pastures. Herbage nitrogen intake of steers grazing on OG and MF pastures averaged 229 and 271 g/day, respectively. Nitrogen flows to the duodenum of steers grazing on orchardgrass and meadowfescue pastures averaged 187 and 195g/d, respectively. Microbial nitrogen flow to the duodenum also did not differ between OG and MF pastures. Efficiencies of nitrogen utilization for microbial protein synthesis per kg organic matter apparently digested in the rumen of steers grazing on OG and MF pastures averaged 31.4 and 29.0g, respectively. There was no significant difference in nitrogen absorption from the intestine between steers grazing on OG and MF pastures. In both pastures, steers were supplied with more than 3.5 times metabolizable protein as much as required for maintenance without supplements