The Evaluation of Encapsulated Megasphaera elsdenii in an Accelerated Beef Step-Up Program and an Acidosis Challenge Model and the Evaluation of RAMP Versus a Traditional Forage Grain Adaptation Strategy on Methane and Respired Carbon Dioxide

Authors

Cindy D. Mansfield, University of Nebraska - LincolnFollow

First Advisor

Jim C. MacDonald

Second Advisor

Galen E. Erickson

Date of this Version

5-2023

Comments

A THESIS Presented to the Faculty of The Graduate College at the University of Nebraska In Partial Fulfillment of Requirements For the Degree of Master of Science, Major: Animal Science (Ruminant Nutrition), Under the Supervision of Professors Jim C. MacDonald and Galen E. Erickson. Lincoln, Nebraska: May, 2023

Copyright (c) 2023 Cindy D. Mansfield

Abstract

A metabolism experiment (Exp 1) was conducted to evaluate daily feeding of encapsulated Megasphaera elsdenii (M. elsdenii) NCIMB 41125 along with a one-time drench of 1×10¹¹ CFU of M. elsdenii on dry matter intake (DMI), in-vitro lactate utilization, volatile fatty acid (VFA), and lactate concentration. Treatments consisted of steers which were fed no M. elsdenii (CONTROL), steers drenched with the commercial dose 1×10¹¹ CFU of M. elsdenii (LactiproNXT) on d 1 of the experiment and received no other M. elsdenii (DRENCH), and steers drenched with a commercial dose of LactiproNXT on d 1 of the experiment and received 1×10⁶ CFU of encapsulated M. elsdenii daily as a top dress (LOW), 1×10⁷ CFU of encapsulated M. elsdenii daily as a top dress (MEDIUM), and 1×10⁸ CFU of encapsulated M. elsdenii daily as a top dress (HIGH). CONTROL was stepped-up to a finisher diet in 18 d and DRENCH, LOW, MEDIUM, and HIGH were stepped-up in 9 d. During the step-up, there were no differences in DMI; however, cattle fed M. elsdenii had increased butyrate by 3% compared to CONTROL. After an acidosis event, DMI increased by 4.6% for LOW, MEDIUM, and HIGH steers compared to DRENCH. Steers fed M. elsdenii daily tended to have a 30% greater utilization of lactate compared to CONTROL. After an acidosis event, cattle fed M. elsdenii daily had a 10% increase in VFA concentration compared to DRENCH. An accelerated step-up was possible with DRENCH and daily feeding of M. elsdenii. A drench and daily feeding of M. elsdenii may have a positive effect during and after an acidosis event. A finishing experiment (Exp 2) was conducted to evaluate RAMP compared with a traditional forage adaptation program on methane (CH₄) emissions and respired carbon dioxide (CO₂), performance, and carcass characteristics of beef cattle. Steers were utilized in 2 adaptation treatments, using 100% RAMP or 43% forage during step 1. All cattle were adapted to the same finishing diet over 22 d. Feeding RAMP during step 1 resulted in 12% decrease in CH₄, in g/d and a 18% lower CH₄:CO_2. Steers fed RAMP during step 1 had an 8% increase in CO₂ g/d due to greater digestibility compared to traditional forage diet. Steers fed RAMP spent 45% less time ruminating and eating compared to CONTROL during step 1. For emissions while on the common finishing diet, steers that had been adapted using RAMP had a 9% lower CH₄, in g/d, 8% lower in CH₄ g/kg DMI, and a lower CH₄:CO₂ suggesting a carryover effect from adaptation. Steers adapted with RAMP tended to have a greater HCW. Feeding RAMP to cattle during the grain adaptation phase resulted in a 12% decrease in CH₄, which carried over to 9% less CH₄ during the finishing phase.

Advisors: James C. MacDonald and Galen E. Erickson