02730naa a2200241 a 450000100080000000500110000800800410001902400370006010000240009724501120012126000090023330000150024249000090025752020420026665000170230865000130232565000110233865300220234965300220237170000190239370000140241277300620242620278732024-07-09       1987    bl uuuu     u00u1 u    #d7 adoi:10.2134/jas1987.641295x2DOI1 aWANDERLEY, R. da C.  aDuodenal bacterial and nonbactaserial and nonbacterial protein supply in steers fed forage and grain diets.  c1987  ap.295 v.64  vv.64  aAbstract: Four beef steers (avg wt 300 kg) fitted with duodenal re-entrant cannulae were used to study the effect of dietary concentrate to forage ratio on bacterial and nonbacterial N flow in the duodenum. According to a change-over design, the steers were designated to receive an all forage (83% alfalfa hay and 17% wheat straw) and an 80% sorghum grain diet. Lignin (ADL) and chromium oxide (Cr2O3) ratio techniques were compared with automated total collection (ATC) of digesta for quantitating duodenal protein flow and efficiency of bacterial N yield in the ramen. Estimates of bacterial protein synthesis and ruminal escape of feed protein based on Cr2O3 and lignin tended to be higher by 8 to 16% than those obtained by ATC. Efficiency of ruminal bacterial protein yield estimated by these two markers tended to be greater than that based on ATC (16 vs 12 g of bacterial protein/100 gruminal true digestion of dry matter corrected for bacterial cell synthesis). Efficiency values did not differ between diets. Crude protein flow into the duodenum was about 33% greater (P&lt.01) for the grain than the forage diet, although protein intake was about 10% less on the grain diet. Duodenal bacterial protein, rather than feed protein escaping ruminal degradation, accounted for most of this difference. Average duodenal flow of N, expressed as g/Mcal metabolizable energy (ME) intake, was 11.9 for the forage diet and 10.3 for the grain diet. Grams of duodenal bacterial N per Mcal ME intake were similar (P&gt.10) for the diets (5.1 vs 5.0), but duodenal nonbacterial N (g/Mcal ME intake) was greater (P&lt.01) for the forage than the grain diet (6.9 vs 5.3). With the grain diet, microbial N production exceeded the amount of feed N degraded in the rumen, presumably by utilizing extensive amounts of recycled N for ruminal bacterial synthesis. Recycled N may be of greater magnitude in grain than forage diets. Dietary concentrate to forage ratios showed a marked effect on ruminal protein digestion and duodenal flow of protein.  aconcentrates  aduodenum  aforage  aMicrobial protein  aProtein digestion1 aTHEURER, C. B.1 aPOORE, M.  tJournal of Animal Sciencegv. 64, n. 1, p. 295-302, 1987.