Use of gallic acid and hydrolyzable tannins to reduce methane emission and nitrogen excretion in beef cattle fed a diet containing alfalfa silage1,2

Abstract

of the Lethbridge Research and Development Centre, AB, Canada, for their invaluable technical assistance. We also thank R. Merrill and the metabolism barn staff for their care of the experimental animals. 2 Lethbridge Research and Development Centre contribution number is 38718065.

Potential of Molecular Weight and Structure of Tannins to Reduce Methane Emissions from Ruminants: A Review

“…Feeding tannins to ruminants improves N utilization by decreasing rumen degradability of CP and sometimes CP digestibility in the total digestive tract, which shifts N excretion from urine to feces and consequently, reduces excretion of the more volatile form of N into the environment [6]. This effect may be independent of source, type, molecular weight (MW) or dose of tannin [7,8].…”

“…Since HT have low MW and are less structurally variable than CT, they appear to result in a more consistent CH 4 reduction effect. The effect of HT on reducing enteric CH 4 production may be due to the gallic acid (GA) subunit [8], although few in vivo studies have characterized the effect of low MW tannins on CH 4 production. Herein, we review the current literature on the potential of CT and HT for decreasing CH 4 production while considering their effects on animal performance.…”

A commentary on methodological aspects of hydrolysable tannins metabolism in ruminant: a perspective view

“…'The biodegradation of HT and its monomers, such as GA, involves decarboxylation into pyrogallol that is further transformed to several intermediates in step-wise enzymatic reactions, to form acetate and butyrate' (Salami et al 2018). 'The metabolites of GA (pyrogallol, resorcinol and phloroglucinol) can be hydrolysed to acetate and butyrate by rumen microbes to generate energy' (Aboagye et al 2019). 'In the short-term study, the beneficial effect of added GA on promoting 48-h carbohydrate fermentation may be explained by the possible decomposition of GA to resorcinol, pyrogallol and phloroglucinol and their subsequent use as potential energy sources by ruminal microorganisms' (Wei et al 2019).…”

“…However, none of them addresses the above concerns. Furthermore, ruminal microbiota (or adaptation, response) and animal evolution (or adaptation, response) in experimentally adapted ruminant for ruminal HT metabolism and whole animal HT metabolism respectively are interesting research questions that are not explored in the studies of Salami et al (2018) and Aboagye et al (2019). In other words, after adaptation, what significant changes in ruminal and whole animal HT metabolism were observed in comparison with before feeding a HT ingredient?…”

“…Although using TA, GA, natural HT-rich ingredients (for example, chestnut hydrolysable tannins) and HT-rich feeds (for example, oak leaves, Pistachio by-product and Terminalia oblongata) in ruminant feeding have been explored extensively, not many studies report the information on the concentration of HT metabolites in biological samples (rumen fluid, blood, liver, urine and animal products) (Doce et al 2009;Rahimi et al 2013;Salami et al 2018;Aboagye et al 2019;Focant et al 2019). To the best of my knowledge, data on the concentration of HT metabolites (mostly pyrogallol) in biological samples in ruminant animals fed HT ingredients (TA, GA, natural HT-rich ingredients and HT-rich feeds) are scarce (Martin 1982;Murdiati et al 1992;Frutos et al 2004b;Gonz alez-Barrio et al 2012).…”