PSXIII-17 - Effects of Dietary Forage Inclusion During Finishing on Growth Performance, Feeding Behavior, and Ruminal Fermentation in Steers at Risk for Acidosis

Wednesday, June 29, 2022

8:15 AM – 9:15 AM CT

Location: Exhibit Hall A

Presenting Author(s)

Colten W. Dornbach, MS

Nesheim Fellow
University of Illinois
Urbana, Illinois, United States

Author(s)

JM

Joshua C. McCann, n/a

Assistant Professor
University of Illinois
Urbana, Illinois, United States

Abstract: The objective was to evaluate the effects of dietary forage inclusion during finishing on growth performance, feeding behavior, and ruminal fermentation in steers at risk for acidosis. Angus × Simmental steers (n = 240; body weight = 350 ± 58 kg) were blocked by body weight and allotted into 18 pens. Feeding behavior was collected and analyzed from the initial 45 d steers were fed a high-moisture corn-based finishing ration in GrowSafe bunks to determine steers (20%) at greatest risk for developing acidosis. The at-risk steers (n = 48) were utilized in a randomized complete block design. Steers were stratified by initial body weight within block and assigned to 8 pens of 6 steers. Pens were randomly assigned to 1 of 2 dietary treatments: (1) 15% (15CS) or (2) 30% corn silage (30CS) on a dry matter basis where corn silage replaced high moisture corn in the finishing diet. Overall body weight, average daily gain, dry matter intake, and gain:feed were not affected (P ≥ 0.19) by treatment. Carcass characteristics were not affected by treatment (P ≥ 0.39). Steers consuming 30CS had greater (P ≤ 0.05) meal frequency and eating rate, as well as decreased meal length, from d 0 to 112. Fluctuations in dry matter intake during the final 56 d of finishing were not affected by treatment (P ≥ 0.20). Ruminal pH was collected prior to feeding and tended to exhibit a treatment × day effect (P = 0.05) with 30CS steers having increased ruminal pH on d 56 and 112. No treatment × day effect was observed for molar proportions of acetate, propionate, and butyrate (P ≥ 0.11) in ruminal fluid. Overall, increasing dietary forage during finishing altered feeding behaviors and ruminal fermentation in steers at risk for acidosis, but did not affect growth performance.