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

Monday, June 27, 2022

11:05 AM – 11:20 AM CT

Location: Oklahoma City Convention Center, 301 A/B

Presenting Author(s)

Kaliu G. Scaranto Silva

Masters Student
Texas Tech University
Lubbock, Texas

Author(s)

JO

Jhones O Sarturi, n/a

Associate Professor
Texas Tech University
Lubbock, TX
DH

Darren H. Henry

Department of Animal and Dairy Science, University of Georgia – Tifton Campus, Tifton, GA 31793-5766, USA
Tifton, GA
BJ

Bradley J. Johnson, PhD

Professor
Texas Tech University
Lubbock, TX
AL

Alejandra M. Lopez

Master's Student
Texas Tech University
Lubbock, Texas
BR

Barbara Rodrigues

Texas Tech University
Lubbock, TX
Kaue Tonelli Nardi

Masters Student
Texas Tech University
Lubbock, TX
CR

Camron J. Rush

Undergraduate Student
Texas Tech University
Lubbock, TX
SP

Sarah Peters

Texas Tech University
Lubbock, TX
AC

Angela Camarillo

Texas Tech University
Lubbock, TX
AW

Ashleigh Wilson

Texas Tech University
Lubbock, TX

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