342 Effects of Direct fed Microbial Mixtures on Beef Cattle Ruminal Fermentation Characteristics, Intake, and Nutrient Digestibility

Abstract Direct fed microbials (DFM) dietary mixture effects on beef cattle ruminal variables, intake, and apparent total tract digestibility were evaluated. Six ruminally cannulated steers (BW = 520 ± 30 kg) used in a duplicated 3 × Latin square design offered steam-flaked corn-based finishing diet ad libitum for three 28-d periods (21-d adaptation 7-d collection). Treatments assigned were: 1) Control (no DFM mixture; lactose only); 2 3) mixtures at distinct concentrations [Mixture A B, g/animal-daily (lactose as carrier)]. Ruminal pH temperature measured every 6 min (wireless probes). samples collected 0, 2, 4, 8, 16, 23 h post-feeding d28. Feed fecal (collected once twice daily, respectively) composited by period analyzed. Fecal output was estimated with internal marker (288-h indigestible-NDF). Data analyzed using the GLIMMIX procedure of SAS. No treatment time interactions (P ≥ 0.20) observed. Steers mixture-A experienced 300 min/d less 0.04) under 5.6, tended 0.13) lesser area curve while showing greater average (5.67 vs. 5.50), 0.06) (39.2 39.4°C) compared to control. The concentration NH3-N 0.02) control (10.78 4.35 mg/dL), animals mixture-B 0.07) be (9.11 mg/dL) than increased ADF (39.8 54.0%), not affecting DM intake 0.61). induced safer environment encouraging fiber degradation release, animal