PSX-A-1 Impacts of Undigestible NDF and Grain Source in Feedlot Steers on Performance, Feeding Behavior, and Ruminal pH

Abstract Little is known about how fiber quality impacts rumen health in feedlot diets with minimal forage inclusion. The objective of the study to investigate interaction between undigestible NDF (uNDF) levels and grain fermentability (GF) on animal performance, feeding behavior, ruminal pH steers. Using a 2x2 factorial design, Angus crossbred steers (n=96, 505±54 kg) were fed an isonitrogenous isocaloric diet containing: high uNDF (haylage; 12% uNDF) or lower (corn silage, 6% (high moisture corn) ruminally fermentable (rolled yielding 4 different treatments. Following adaption, their treatment ration for 102±14d before slaughter. Feed intake (DMI) behavior data collected using Insentec feeders continuous was measured during last weeks slaughter indwelling probes (12 steers/treatment). Liver abscesses gut scores assessed at Steers low had greater ADG (P≥0.005) improved F:G first half finisher period. No other differences performance traits found second overall period GF, interaction. DMI (P≥0.64) did not differ, but time spent feeder (min/day) (P≥0.02) GF (P≥0.04) per day below 5.8. At slaughter, treatments hot carcass weights (P≥0.03). This suggests that can improve early gain may result increased SARA risk compared same inclusion level. However, there limited processing. Further research should continue relationships pH, dietary concentrations optimize without compromising health.