Effects of condensed tannins supplementation on animal performance, phylogenetic microbial changes and in vitro methane emissions in steers grazing winter wheat

Authors: Min, Byeng Ryel; PINCHAK, WILLIAM - Texas A&M Agrilife; Hume, Michael; Anderson, Robin

Submitted to: Animals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/9/2021
Publication Date: 8/13/2021
Citation: Min, B., Pinchak, W.E., Hume, M.E., Anderson, R.C. 2021. Effects of condensed tannins supplementation on animal performance, phylogenetic microbial changes and in vitro methane emissions in steers grazing winter wheat. Animals. 11(8). Article 2391. https://doi.org/10.3390/ani11082391.
DOI: https://doi.org/10.3390/ani11082391

Interpretive Summary: Grazing wheat pasture is a common practice throughout the southeastern and south-central United States; however, the practice is limited by concerns regarding the occurrence of bloat. In addition, there are few reports concerning methane production by cattle grazing wheat pasture. There is a growing interest in the use of plant condensed tannins as the alternative natural feed additives to control bloat and mitigate methane production. However, the effects of condensed tannins supplementation on in vitro gas production, rumen microflora and animal performance in stocker cattle grazing wheat forage are not fully defined. Therefore, scientists from USDA-ARS at Bushland, TX, and Texas A&M University, TX, analyzed the effects of dietary condensed tannins on in vitro methane gas production, animal performance, and microbiome profiles. Supplementation with condensed tannins induced changes in ruminal bacteria, reduced methane emissions, and increased animal performance. These data indicate that condensed tannin supplementation may benefit stocker producers who graze wheat pasture for growing beef cattle by decreasing the incident of bloat and increasing animal performance by changing rumen fermentation.

Technical Abstract: Grazing stocker cattle on winter wheat from fall to early spring months is commonly practiced on the Southern Great Plains, a dual-use winter wheat region. Wheat pastured cattle frequently experience frothy bloat during this grazing. Excessive dietary amounts of rapidly degradable soluble protein and low fiber content are primary precursors for development of frothy bloat. Supplementation with condensed tannins (CT) may decrease frothy bloat incidence and improve animal performance in stocker cattle grazing wheat. Two experiments were conducted to: 1) enumerate the effects of ruminal fluid from eighteen cannulated steers fed different dosages of quebracho CT (0%, 1%, and 2% CT/kg dry matter intake [DMI]) on in vitro gas and methane (CH4) production (Exp. 1); and 2) quantify the influence of CT supplementation on animal performance and microbial community changes of steers grazing winter wheat forage (Exp. 2). Rumen bacterial microbiota genomic guanines and cytosines (GC) diversity changes from individual steers were analyzed by a denaturing gel gradient electrophoresis (DGGE) using a percentage similarity coefficient (% SC). In Exp.1, in vitro total gas, potential gas, and CH4 productions decreased (P < 0.01) by 38%, 32%, and 70.8%, respectively, as CT supplementation increased in steers grazing wheat forage. In Exp. 2, initial body weight (BW) was similar among treatments, but final BW was greater (P < 0.02) for the 2% CT treatment group compared to either 1% CT or control groups. Rumen bacterial populations in cannulated steers fed winter wheat forage in the absence of CT supplementation represented large proportions of the moderate-GC containing bacterial clusters with similarity ranging from 64% to 92% SC (Fig. 2). In the presence of CT on day 0, day 20, and day 60, however, the similarity was 60% or greater (90% SC) with multiple bacterial band clusters as shown by the DGGE banding patterns, except for steer #11 (< 61% SC) on day 20 (Fig. 3). Multiple bacterial band clusters were common in all 1% CT samples, while one or two major band clusters were common in steers fed winter wheat pasture in the absence of CT. When steers received 2% CT supplementation, multiple banding patterns were seen in steers grazing winter wheat forage, with 62% to 92% SC, but increasingly low-GC-containing bacterial communities were present (Fig. 4), except for steers #16 and #18. These results suggested that the administration of CT inducanges in the rumen of steers grazing wheat forage. Quebracho CT is potentially a value-added supplement that can decrease the impacts of CH4 emissions and increase BW gain in stocker cattle wheat pasture systems.