Abstract
We studied the effect of different levels of beet-pulp supplementation on nitrogen (N) intake, microbial N synthesis in the rumen, and duodenal flows of amino acids insteers grazing pasture. Three Holstein steers fitted with cannulas in the rumen and duodenum were grazed on orchardffrass (Dactylis glomerata L.) pasture and supplement with 0,15 or 30g/per metabolic body size of beet-pulp (BP0, BP15, BP30) in a 3×3 Latin square design. The pasture was divided into several paddocks, and the steers grazed each paddock for a day. The OM intake from pasture decreased with beet pulp supplementation but there was no difference in total OM intake among treatments. Total N and amino acid N intake decreased with beet-pulp supplementation (P<0.05). The ammonium N concentration in rumen fluid (mg/dL) was significantly lower in BP30 than in BP0 steers. Although duodenal non-ammonia N and amino acid N now did not differ among treatments, supplementing with beet-pulp decreased the N absorption from the rumen and increased the proportion of non-ammonia N and amino acid to duodenum.
