Influence of method of forage preservation on fibre and protein digestion in cattle given lucerne, birdsfoot trefoil and sainfoin

Abstract

ABSTRACTSix steers, each fitted with a ruminal cannula and T-type duodenal and ileal cannulae, were used to investigate protein and fibre utilization from lucerne, birdsfoot trefoil and sainfoin preserved both as hay and silage. Steers were fed at 2-h intervals during six 12-day periods in an experiment with a 6 × 6 Latin-square design. Animals were fed all-forage diets of six treatments (lucerne hay and silage, birdsfoot trefoil hay and silage, sainfoin hay and silage). Samples were collected from all alimentary sites twice daily during the last 3 days of each period. Acid insoluble ash was used as a solid marker and Cr-ethylene diamine tetra-acetic acid as a liquid marker. Organic matter (OM), hemicellulose (HC) and cellulose (CL) total tract digestibilities of lucerne, birdsfoot trefoil and sainfoin were similar (OM: 599, 608, 580 g/kg; HC: 499, 497, 480 g/kg; CL: 590, 618, 608 g/kg). However, crude protein (CP) digestibilities were lower (P < 0·001) for sainfoin (582 g/kg) than for lucerne (732 g/kg) or birdsfoot trefoil (693 g/kg). Nitrogen (N) flows at the duodenum or ileum were similar among forages despite lower N intake for sainfoin. Presence of tannins in sainfoin may have been responsible for low protein degradation in the rumen, and reduced N digestion in the small intestine. Forage preserved as hay or silage had similar CL, HC and OM digestibilities, while CP digestibility was higher (P < 0·05) for silages.