Use of Asian selected agricultural byproducts to modulate rumen microbes and fermentation

Abstract

In the last five decades, attempts have been made to improve rumen fermentation and host animal nutrition through modulation of rumen microbiota. The goals have been decreasing methane production, partially inhibiting protein degradation to avoid excess release of ammonia, and activation of fiber digestion. The main approach has been the use of dietary supplements. Since growth-promoting antibiotics were banned in European countries in 2006, safer alternatives including plant-derived materials have been explored. Plant oils, their component fatty acids, plant secondary metabolites and other compounds have been studied, and many originate or are abundantly available in Asia as agricultural byproducts. In this review, the potency of selected byproducts in inhibition of methane production and protein degradation, and in stimulation of fiber degradation was described in relation to their modes of action. In particular, cashew and ginkgo byproducts containing alkylphenols to mitigate methane emission and bean husks as a source of functional fiber to boost the number of fiber-degrading bacteria were highlighted. Other byproducts influencing rumen microbiota and fermentation profile were also described. Future application of these feed and additive candidates is very dependent on a sufficient, cost-effective supply and optimal usage in feeding practice.

Rumen responses to dietary supplementation with cashew nut shell liquid and its cessation in sheep

“…The mode of action for the microbial selection by CNSL is attributed to the surfactant action of alkylphenols, as represented by anacardic acid (Kobayashi et al 2016). This compound should be kept intact to ensure stable function.…”

“…This compound should be kept intact to ensure stable function. In fact, heat-treated CNSL shows weakening or loss of antimicrobial function (Branco et al 2015), thereby decreasing its rumen modulatory function (Kobayashi et al 2016). Technological developments in processing CNSL without heat treatment ensures the functionality of CNSL in ruminant livestock at practical levels.…”

“…As alternatives to ionophore antibiotics, many natural products exerting ionophore-like actions have been actively explored. These alternatives include plant extracts such as tannins, saponins and essential oils containing cinnamaldehyde and eugenol (Calsamiglia et al 2007;Kobayashi et al 2016). The main action of these compounds is the reduction of ammonia and increase of propionate in the rumen.…”

Does intra-ruminal nitrogen recycling waste valuable resources? A review of major players and their manipulation

“…As summarized by Kobayashi et al [ 179 ], anacardic acids predominantly present in the by-products of cashew ( Anacardium occidentale ) and ginkgo ( Ginkgo biloba ) nut production, are discussed as modifiers of rumen fermentation. Anacardic acids are characterized as a group of few closely related organic compounds, differing in saturation and side chain length [ 180 ].…”

“…16S rDNA copies of P. ruminicola increased with ginkgo extract [ 181 ], but declined when cashew nut shell liquid was added [ 182 ]. This inconsistency may be explained by differences in the structure of anacardic acids contained in ginkgo and cashew by-products [ 181 ] or also by the presence of other antimicrobial compounds [ 179 ]. As both studies used similar diets for the in vitro incubation as well as bead beating-based DNA extractions and identical primers for qPCR analysis, laboratory procedures may not have been a contributing factor for the deviating microbial abundances.…”