Journal Article

Links between the rumen microbiota, methane emissions and feed efficiency of finishing steers offered dietary lipid and nitrate supplementation

Cormican, Paul, Dewhurst, Richard J., Roehe, Rainer, McCabe, Matthew S., Bowen, Jenna M., Lister, Susan J., Duthie, Carol-Anne

2020

Overview

Ruminant methane production is a significant energy loss to the animal and major contributor to global greenhouse gas emissions. However, it also seems necessary for effective rumen function, so studies of anti-methanogenic treatments must also consider implications for feed efficiency. Between-animal variation in feed efficiency represents an alternative approach to reducing overall methane emissions intensity. Here we assess the effects of dietary additives designed to reduce methane emissions on the rumen microbiota, and explore relationships with feed efficiency within dietary treatment groups. Seventy-nine finishing steers were offered one of four diets (a forage/concentrate mixture supplemented with nitrate (NIT), lipid (MDDG) or a combination (COMB) compared to the control (CTL)). Rumen fluid samples were collected at the end of a 56 d feed efficiency measurement period. DNA was extracted, multiplexed 16s rRNA libraries sequenced (Illumina MiSeq) and taxonomic profiles were generated. The effect of dietary treatments and feed efficiency (within treatment groups) was conducted both overall (using non-metric multidimensional scaling (NMDS) and diversity indexes) and for individual taxa. Diet affected overall microbial populations but no overall difference in beta-diversity was observed. The relative abundance of Methanobacteriales (Methanobrevibacter and Methanosphaera) increased in MDDG relative to CTL, whilst VadinCA11 (Methanomassiliicoccales) was decreased. Trimethylamine precursors from rapeseed meal (only present in CTL) probably explain the differences in relative abundance of Methanomassiliicoccales. There were no differences in Shannon indexes between nominal low or high feed efficiency groups (expressed as feed conversion ratio or residual feed intake) within treatment groups. Relationships between the relative abundance of individual taxa and feed efficiency measures were observed, but were not consistent across dietary treatments.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Abundance / Additives / Air pollution / Air pollution control / Animal Feed / Animal Husbandry - methods / Animals / Beef cattle / Biodiversity / Biology and Life Sciences / Cattle / Cattle feed / Conversion ratio / Cytotoxicity / Deoxyribonucleic acid / Diet / Dietary Fats - administration & dosage / Dietary Supplements / DNA / DNA, Bacterial - isolation & purification / Earth Sciences / Ecology and Environmental Sciences / Efficiency / Emissions / Energy dissipation / Energy loss / Feed additives / Feed conversion / Feed efficiency / Feeds / Gastrointestinal Microbiome - physiology / Grasslands / Greenhouse effect / Greenhouse Effect - prevention & control / Greenhouse gases / Greenhouse Gases - metabolism / Legal fees / Library collections / Lipids / Lymphocytes T / Male / Medicine and Health Sciences / Methane / Methane - metabolism / Methane emissions / Methane production / Methanobacteriaceae - genetics / Methanobacteriaceae - isolation & purification / Methanobacteriaceae - metabolism / Methanobacteriales - genetics / Methanobacteriales - isolation & purification / Methanobacteriales - metabolism / Methanobrevibacter - genetics / Methanobrevibacter - isolation & purification / Methanobrevibacter - metabolism / Microbiota / Microbiota (Symbiotic organisms) / Microorganisms / Multidimensional scaling / Nucleotide sequence / Physical Sciences / Rapeseed / Relative abundance / RNA / RNA, Ribosomal, 16S - genetics / rRNA 16S / Rumen / Rumen - drug effects / Rumen - microbiology / Scotland / Studies / T cells / Taxa / Taxonomy / Trimethylamine