Phytogenic Additives Can Modulate Rumen Microbiome to Mediate Fermentation Kinetics and Methanogenesis Through Exploiting Diet–Microbe Interaction

Abstract

Ruminants inhabit the consortia of gut microbes that play a critical functional role in their maintenance and nourishment by enabling them to use cellulosic and non-cellulosic feed material. These gut microbes perform major physiological activities, including digestion and metabolism of dietary components, to derive energy to meet major protein (65–85%) and energy (ca 80%) requirements of the host. Owing to their contribution to digestive physiology, rumen microbes are considered one of the crucial factors affecting feed conversion efficiency in ruminants. Any change in the rumen microbiome has an imperative effect on animal physiology. Ruminal microbes are fundamentally anaerobic and produce various compounds during rumen fermentation, which are directly used by the host or other microbes. Methane (CH 4 ) is produced by methanogens through utilizing metabolic hydrogen during rumen fermentation. Maximizing the flow of metabolic hydrogen in the rumen away from CH 4 and toward volatile fatty acids (VFA) would increase the efficiency of ruminant production and decrease its environmental impact. Understanding of microbial diversity and rumen dynamics is not only crucial for the optimization of host efficiency but also required to mediate emission of greenhouse gases (GHGs) from ruminants. There are various strategies to modulate the rumen microbiome, mainly including dietary interventions and the use of different feed additives. Phytogenic feed additives, mainly plant secondary compounds, have been shown to modulate rumen microflora and change rumen fermentation dynamics leading to enhanced animal performance. Many in vitro and in vivo studies aimed to evaluate the use of plant secondary metabolites in ruminants have been conducted using different plants or their extract or essential oils. This review specifically aims to provide insights into dietary interactions of rumen microbes and their subsequent consequences on rumen fermentation. Moreover, a comprehensive overview of the modulation of rumen microbiome by using phytogenic compounds (essential oils, saponins, and tannins) for manipulating rumen dynamics to mediate CH 4 emanation from livestock is presented. We have also discussed the pros and cons of each strategy along with future prospective of dietary modulation of rumen microbiome to improve the performance of ruminants while decreasing GHG emissions.

Effect of Oregano Oil and Cobalt Lactate on Sheep In Vitro Digestibility, Fermentation Characteristics and Rumen Microbial Community

“…Previous studies had shown different effects of oregano essential oil and cobalt on rumen microbial activity and fermentation characteristics in ruminants due to different additive types and adding levels [ 16 ], which may be related to the type of EO, its structure and the substrate employed. Therefore, to develop new additives for EO binding to ultimately effectively regulate ruminant production, in this study, the effects of different gradients of oregano essential oil and cobalt lactate binding on nutrient digestibility, rumen fermentation patterns and microbiota were evaluated by in vitro incubation.…”

“…These experiments showed that providing a mixture of Co and EO improved rumen fermentation capacity and altered VFA patterns, resulting in improved digestibility of dry matter, protein and fiber. However, previous studies on oregano EO and Co have yielded inconsistent results on the basis of the amount and type of EO additive, and few studies have reported relationships between rumen microbes and rumen fermentation parameters and feed digestibility [ 16 ]. This study hypothesized that different levels of EOC addition would have different effects on rumen microorganisms, while nutrient digestibility and fermentation parameters might change with the microbiota altered.…”

Specific inhibition of Streptococcus bovis by endolysin LyJH307 supplementation shifts the rumen microbiota and metabolic pathways related to carbohydrate metabolism

“…Several agents to inhibit ruminal bacteria were evaluated in an in vitro system, and the ability to change the rumen microbiota and rumen fermentation has been shown [ 45 – 47 ]. Shen, Liu, Yu (47) reported that monensin and nisin supplementation decreased the absolute abundance of total bacteria and overall rumen fermentation (gas and VFA production) with a concomitant change in the major rumen microbiota.…”

Understanding microbial networks of farm animals through genomics, metagenomics and other meta-omic approaches for livestock wellness and sustainability – A Review

“…For example, the cervical barrier is crossed, allowing the microbial entry from the vagina or environment or skin into the genital tract (Ochiel et al, 2008). Porphyromonas, Bacteroidetes, and Fusobacterium inhabiting rumen are excreted but also add to the possibilities of uterus infection leading to metritis (Hassan et al, 2020;Wang et al, 2013). The prevalence of microbes in livestock environments can easily cross the host's defense system and establish a niche in the uterus (Baker et al, 2018).…”