Replacing Barley and Soybean Meal With By-products, in a Pasture Based Diet, Alters Daily Methane Output and the Rumen Microbial Community in vitro Using the Rumen Simulation Technique (RUSITEC)

Abstract

Plant based by-products (BP) produced from food and bioethanol industries are human inedible, but can be recycled into the global food chain by ruminant livestock. However, limited data is available on the methanogenesis potential associated with supplementing a solely BP formulated concentrate to a pastoral based diet. Therefore the objective of this in vitro study was to investigate the effects of BP inclusion rate (in a formulated concentrate) to a pasture based diet on dietary digestibility, rumen fermentation patterns, methane production and the prokaryotic microbial community composition. Diets consisted of perennial ryegrass and one of two supplementary concentrates, formulated to be isonitrogenous (16% CP) and isoenergetic (12.0 MJ/ME/kg), containing either 35% BP, barley and soybean meal (BP35) or 95% BP (BP95) offered on a 50:50 basis, however, starch, NDF and fat content varied. The BPs, included in equal proportions on a DM basis, were soyhulls, palm kernel expeller and maize dried distillers grains. The BP35 diet had greater (P < 0.05) digestibility of the chemical constituents DM, OM, CP, NDF, ADF. Greater total VFA production was seen in the BP35 diet (P < 0.05). Daily methane production (mmol/day; +22.7%) and methane output per unit of total organic matter digested (MPOMD; +20.8%) were greatest in the BP35 diet (P < 0.01). Dietary treatment influenced microbial composition (PERMANOVA; P = 0.023) with a greater relative abundance of Firmicutes (adj P < 0.01) observed in the BP35. The Firmicutes:Bacteroidetes ratio was significantly reduced in the BP95 diet (P < 0.01). The relative proportions of Proteobacteria (adj P < 0.01), Succinivibrionaceae (adj P < 0.03) and Succinivibrio (adj P = 0.053) increased in the BP95 diet. The abundance of Proteobacteria was found to be negatively associated with daily methane production (r s , −0.71; P < 0.01) and MPOMD (r s , −0.65; P < 0.01). Within Proteobacteria, the relationship of methane production was maintained with the mean abundance of Succinivibrio (r s , −0.69; P < 0.01). The abundance of

Phenotypic relationship and repeatability of methane emissions and performance traits in beef cattle using a GreenFeed system

“…Reducing CH 4 emissions, therefore, not only improves the environmental sustainability but also the efficiency of both dairy and beef cattle production systems. As such, numerous mitigation strategies for the reduction of CH 4 have been developed, including the use of feed additives ( Gao et al, 2011 ; Smith et al, 2020 ; Almeida et al, 2021 ), nutritional management practices such as increased feed quality ( Beauchemin et al, 2008 ), indirect genetic selection, for example, residual feed intake to reduce methane emissions per kilogram of product and animal performance improvements in milk yields and meat production ( O’Brien et al, 2016 ; Thompson and Rowntree, 2020 ), and direct genetic selection for reduced emissions ( Donoghue et al, 2016a ; González-Recio et al, 2020 ; Lassen and Difford, 2020 ; de Haas et al, 2021 ; Manzanilla-Pech et al, 2021 ). However, before mitigation strategies relating to genetic selection can be implemented, a clear understanding of the CH 4 phenotype and associated measurement methods is first required.…”

Effect of brown and green seaweeds on diet digestibility, ruminal fermentation patterns and enteric methane emissions using the rumen simulation technique

“…The rumen simulation technique (RUSITEC) system designed by Czerkawski and Breckenridge (1977) has been used to assess dietary feed additives such as tannins, essential oils, plant secondary metabolites (Tedeschi et al, 2022), and seaweeds (Belanche et al, 2016a) on total gas output, CH 4 production, digestibility parameters (Smith et al, 2020), and volatile fatty acid (VFA) production (Castro-Montoya et al, 2012). This system is an ideal example of both the reduction and refinement concepts for animal science experimentation, whereby feed additives can be screened for their antimethanogenic properties prior to being brought forward to in vivo animal experiments, which can be expensive, time consuming and labour intensive.…”

Enteric methane research and mitigation strategies for pastoral-based beef cattle production systems

“…Subsequently, this issue may be overcome by formulating rations from a combination of BPs, with both Whelan et al (212) and Condren et al (213) reporting no differences in N excretion between dairy cows receiving a barely and soybean meal supplemented ration in comparison with a BP ration formulated from DDGS, palm kernel expeller, and soyhulls. Indeed, the same BP formulation was also shown to reduce CH 4 output by ∼20% (both daily and per unit of OMD) without negatively impacting members of the rumen microbiota when supplemented with a pasture-based diet in vitro (199).…”

“…Furthermore, rumen microbes possess a limited ability to ferment lipids (198). As a result, the addition of lipids to the diet, at the expense of other carbohydrate sources, likely results in a lower availability of fermentable substrate, leading to less VFA, H 2 , and ultimately CH 4 production per unit of intake and/or digestibility (199). The supplementation of lipids has been identified as a costly CH 4 mitigation strategy (103), which may limit its use due to its economic viability (10).…”