Does Dietary Mitigation of Enteric Methane Production Affect Rumen Function and Animal Productivity in Dairy Cows?

Abstract

It has been suggested that the rumen microbiome and rumen function might be disrupted if methane production in the rumen is decreased. Furthermore concerns have been voiced that geography and management might influence the underlying microbial population and hence the response of the rumen to mitigation strategies. Here we report the effect of the dietary additives: linseed oil and nitrate on methane emissions, rumen fermentation, and the rumen microbiome in two experiments from New Zealand (Dairy 1) and the UK (Dairy 2). Dairy 1 was a randomized block design with 18 multiparous lactating cows. Dairy 2 was a complete replicated 3 x 3 Latin Square using 6 rumen cannulated, lactating dairy cows. Treatments consisted of a control total mixed ration (TMR), supplementation with linseed oil (4% of feed DM) and supplementation with nitrate (2% of feed DM) in both experiments. Methane emissions were measured in open circuit respiration chambers and rumen samples were analyzed for rumen fermentation parameters and microbial population structure using qPCR and next generation sequencing (NGS). Supplementation with nitrate, but not linseed oil, decreased methane yield (g/kg DMI; P<0.02) and increased hydrogen (P<0.03) emissions in both experiments. Furthermore, the effect of nitrate on gaseous emissions was accompanied by an increased rumen acetate to propionate ratio and consistent changes in the rumen microbial populations including a decreased abundance of the main genus Prevotella and a decrease in archaeal mcrA (log10 copies/ g rumen DM content). These results demonstrate that methane emissions can be significantly decreased with nitrate supplementation with only minor, but consistent, effects on the rumen microbial population and its function, with no evidence that the response to dietary additives differed due to geography and different underlying microbial populations.

Effect of Dietary Fat on the Metabolism of Energy and Nitrogen, Serum Parameters, Rumen Fermentation, and Microbiota in twin Hu Male Lambs

“…It also contributes to the majority of hereditary and metabolic varieties of the microflora [45]. Furthermore, Prevotella is the most abundant genus in adult rumen [46,47]. This is in agreement with our result, which show that Prevotella is predominantly composed of this genus when a high-caloric diet is consumed [48].…”

The Structural and Functional Capacity of Ruminal and Cecal Microbiota in Growing Cattle Was Unaffected by Dietary Supplementation of Linseed Oil and Nitrate

“…While in vitro, W. succinogenes possessed higher activity (Iwamoto et al, 2002), in vivo S. ruminantium is the most abundant (Asanuma et al, 2015; Veneman et al, 2015). Accordingly, in our study we only detected sequences affiliated to the genus Selenomonas .…”

Invited review: Large-scale indirect measurements for enteric methane emissions in dairy cattle: A review of proxies and their potential for use in management and breeding decisions

“…Other compounds known for their antimicrobial activities were also shown to induce reductions in both MeP and methanogen numbers (Kubo et al, 1993;Iwamoto et al, 2002). Examples of these are nitrates (van Zijderveld et al, 2010;Veneman et al, 2015), anacardic acid contained in cashew nut shell liquid (Shinkai et al, 2012), monensin (Shinkai et al, 2012), and isobutyrate (Wang et al, 2015). The relationship between rumen methanogen abundance and methanogenesis is less clear when changes in enteric CH 4 emissions are modulated by diet or are a consequence of selecting phenotypes related to feed efficiency or MeY.…”