Impact on Site and Extent of Digestion of Feeding a Corn Hybrd Containing Alpha Amylase in Finishing Cattle Diets

Abstract Text: For cattle to maximize feed efficiency, full utilization of starch digestion must occur. Our objectives were to evaluate feeding cattle corn containing an alpha amylase enzyme (Syngenta Enhanced Feed Corn™; SYT-EFC) on site and extent of digestion and ruminal pH parameters.  Four ruminally and duodenally cannulated steers (BW = 264 ± 13 kg) were utilized in a 6x4 Latin rectangle design with a 2x2+1 factorial arrangement of treatments.  Factors included corn trait (SYT-EFC or CON), corn by-product type [Sweet Bran (SB) or modified distillers grains plus solubles (MDGS)], and a 50:50 blend of SYT-EFC and CON with MDGS.  Period length was 21 d which consisted of 16 d adaptation and 5 d fecal and duodenal collection. Rumen microbial samples were collected via whole rumen contents on d 21 and were analyzed for purines.  Titanium dioxide was dosed intraruminally on d 10-20 as a marker to determine digestibility and fecal output.  Ruminal pH was measured continuously from d 17 to 21 with submersible, wireless pH probes.  No interactions (P > 0.18) or main effect of corn trait (P > 0.43) were observed for true ruminal starch or OM digestibilities.  However, a tendency was observed for postruminal starch (P = 0.11) digestibility to be greater for steers fed SYT-EFC than CON.  Postruminal OM digestibility was also increased in steers fed SYT-EFC compared to CON (P = 0.08).  This resulted in steers fed SYT-EFC to have a decrease in fecal starch (P = 0.01) and OM (P = 0.05) output compared to CON. Ultimately, steers fed SYT-EFC had increased total tract starch, OM, and DM digestibilities (P = 0.01, P = 0.07, and P = 0.08, respectively) compared to CON.  There were no interactions (P > 0.19) or main effect of corn trait (P> 0.30) for ruminal pH characteristics.  These data would suggest that steers fed SYT-EFC were able to utilize starch in the small intestine to a greater extent than cattle fed CON leading to an overall greater total tract starch digestibility and ultimately improved feed efficiencies.

Keywords: Alpha amylase, Finishing cattle, Starch utilization