Effect of corn processing on starch digestion and bacterial crude protein flow in finishing cattle.
Six ruminally and duodenally cannulated yearling steers (523 kg) were used in a replicated 3 x 3 Latin square design experiment to study the effects of corn processing on nutrient digestion, bacterial CP production, and ruminal fermentation. Dietary treatments consisted of 90% concentrate diets that were based on dry-rolled (DRC), high-moisture (HMC), or steam-flaked (SFC) corn. Each diet contained 2.0% urea (DM basis) as the sole source of supplemental nitrogen. Each period lasted 17 d, with d 1 through 14 for diet adaptation and d 15 through 17 for fecal, duodenal, and ruminal sampling. Dry matter and OM intakes were similar for DRC and SFC but were approximately 15% higher (P < 0.05) for HMC. True ruminal OM digestibilities were 18 and 10% greater (P < 0.05) for HMC than for DRC or SFC, respectively. Ruminal starch digestibilities were similar between HMC and SFC and were approximately 19% greater (P < 0.05) than DRC. Postruminal OM digestibility was similar among treatments; however, postruminal starch digestibility was 15% greater (P < 0.05) for SFC than for DRC or HMC, which were similar. Total-tract DM and OM digestibilities were similar between HMC and SFC and were 4% greater (P < 0.05) than DRC. Likewise, total-tract starch digestibilities were similar between HMC and SFC and were 3% greater (P < 0.05) than DRC. Bacterial CP flow to the duodenum was 29% greater (P < 0.05) for HMC than for DRC or SFC, which were similar. Bacterial N efficiencies were similar among treatments. Based on bacterial CP flow from the rumen, we estimate that dietary DIP requirements are approximately 12% higher for HMC-based diets than for DRC or SFC-based diets, which were similar.
Cooper
R J
RJ
Department of Animal Science, University of Nebraska, Lincoln 68583-0908, USA.
Milton
C T
CT
Klopfenstein
T J
TJ
Scott
T L
TL
Wilson
C B
CB
Mass
R A
RA
D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis*; D002417:Cattle / Q000378:metabolism / Q000502:physiology*; D004063:Digestion; D004386:Duodenum / Q000378:metabolism / Q000382:microbiology; D005243:Feces; D005511:Food Handling / Q000379:methods*; D008297:Male; D009751:Nutritional Requirements; D012417:Rumen / Q000378:metabolism* / Q000382:microbiology*; D013213:Starch / Q000378:metabolism*; D003313:Zea mays
D001426:Bacterial Proteins; D013213:Starch