Incubation Temperature, But Not Pequi Oil Supplementation, Affects Methane Production, and the Ruminal Microbiota in a Rumen Simulation Technique (Rusitec) System

Abstract

Lipid supplementation is a promising strategy for methane mitigation in cattle and has been evaluated using several different lipid sources. However, limited studies have assessed the effect of temperature on methane emissions from cattle and changes in incubation temperature have also not been extensively evaluated. The aim of this study was to evaluate the combined effect of pequi oil (high in unsaturated fatty acids) and incubation temperature on fermentation characteristics and microbial communities using the rumen simulation technique. A completely randomized experiment was conducted over a 28-day period using a Rusitec system. The experiment was divided into four periods of 7 days each, the first of which was a 7-day adaptation period followed by three experimental periods. The two treatments consisted of a control diet (no pequi oil inclusion) and a diet supplemented with pequi oil (1.5 mL/day) which increased the dietary fat content to 6% (dry matter, DM-basis). Three fermenter vessels (i.e., replicates) were allocated to each treatment. In the first experimental period, the incubation temperature was maintained at 39°C, decreased to 35°C in the second experimental period and then increased again to 39°C in the third. Pequi oil was continuously supplemented during the experiment. Microbial communities were assessed using high-throughput sequencing of the archaeal and bacterial 16S rRNA gene. Methane production was reduced by 57% following a 4°C decrease in incubation temperature. Supplementation with pequi oil increased the dietary fat content to 6% (DM-basis) but did not affect methane production. Analysis of the microbiota revealed that decreasing incubation temperature to 35°C affected the archaeal and bacterial diversity and richness of liquid-associated microbes, but lipid supplementation did not change microbial diversity.

Application of MootralTM Reduces Methane Production by Altering the Archaea Community in the Rumen Simulation Technique

“…The family Methanobacteria with its genera Methanobrevibacter and Methanosphaera was dominant followed by Thermoplasmatales, Incertae sedis , and Methanomicrobium . These archaea are typically found in the rumen in in vivo and in vitro studies ( Janssen and Kirs, 2008 ; Henderson et al, 2015 ; Duarte et al, 2017a , b ). Several differences in the abundance of individual OTUs were detected among treatment groups.…”

Humic Substances Alter Ammonia Production and the Microbial Populations Within a RUSITEC Fed a Mixed Hay – Concentrate Diet

“…The substrate used was a hay:concentrate (60:40 DM basis) diet using hay obtained from natural grassland of Lower Saxony, Germany. Hay was prepared using an electrical clipper with a 76- mm blade ( Duarte et al, 2017 ). The commercial concentrate was pelleted (Deuka Schaffutter, Deutsche Tiernahrung Cremer, Düsseldorf, Germany) and contained 20% crude protein, 2.6% crude fat, 11.0% crude fiber, 8.7% crude ash, 0.9% calcium, 0.55% phosphor and 0.2% sodium.…”

“…After removal from the vessel, feed bags were washed in 50 mL of warmed buffer in a small plastic bag, gently squeezed and the residual buffer was placed back into the fermenter to ensure transfer of solid-phase-associated microorganisms. The residual feed bag was rinsed under cold water until the water was clear and then dried at 55°C for 48 h for the determination of DMD ( Duarte et al, 2017 ). After drying, substrate samples from day 9, 10, and 14 were taken from the bag and ground using a coffee grinder for NDF analysis.…”

Unconventional Vegetable Oils for a Reduction of Methanogenesis and Modulation of Ruminal Fermentation

“…The lack of change of microbial diversity is supported by Duarte et al ( 31 ) who found that the archaeal and bacterial microbiota structure was not affected by pequi oil supplementation using the rumen simulation technique. However they did report that pequi oil increased the relative abundance of Anaerovibrio , a genus that has reported to be involved in the metabolism of lipids in the rumen, enhancing propionate synthesis ( 37 , 38 ).…”

“…In contrast to this, Duarte et al ( 30 , 31 ) demonstrated that pequi oil included at 1.5 mL/d, increasing the dietary fat content to 6.0%, had no effect on in vitro CH 4 production using the rumen simulation technique (RUSITEC). However, authors state that this may have been due to the small concentration of pequi oil tested in relation to fermentation liquid.…”