Year: 2026
Type: article
Abstract: This study investigated the effects of narasin supplementation on the ruminal and cecal bacterial communities of feedlot Nellore cattle. We hypothesized that narasin would selectively modulate microbial populations in distinct gastrointestinal compartments without causing broad-scale disruption of overall community diversity. Sixty-four Nellore bulls (393 ± 24 kg) were assigned to a completely randomized block design and fed finishing diets containing either 0 or 20 ppm of narasin for 112 days. Rumen and cecal contents were collected at slaughter and analyzed using 16S rRNA gene sequencing to characterize bacterial community structure and composition. Overall, the rumen exhibited greater bacterial diversity and richness than the cecum, regardless of dietary treatment. Narasin supplementation did not affect Shannon diversity in either the rumen ( p = 0.182) or the cecum ( p = 0.298); however, Chao richness was reduced in the rumen of narasin-fed cattle ( p = 0.028). Beta-diversity analyses based on Bray–Curtis and Jaccard dissimilarities revealed no significant differences in overall community structure between treatments in either compartment ( p > 0.198). At the phylum level, narasin supplementation was associated with a reduction in Firmicutes and a concomitant increase in Bacteroidetes in the rumen. In contrast, Firmicutes predominated in the cecum, and narasin significantly increased the relative abundance of this phylum, particularly members of the order Clostridiales ( p = 0.05). In conclusion, narasin exerts selective effects on specific bacterial populations rather than inducing widespread shifts in microbial diversity. These results provide novel insights into how narasin modulates microbial ecology in both the rumen and the understudied cecum, highlighting compartment-specific responses that may contribute to improved feed efficiency in beef cattle.
Source: Frontiers in Microbiology
Authors: Johnny M. Souza, Leandro A. F. Silva, Daniel M. Casali, Janaina C. S. M. Souza, Luke A. Wolfe, Joseph H. Skarlupka, Ibrahim Zuniga-Chaves, Andrew J. Steinberger, Courtney L. Deblois, Andrew J. Scheftgen, Ana L. J. Lelis, Tiago Leiva, Murilo Chuba Rodrigues, José Paulo Roman Barroso, Pedro Veloso Facuri Lasmar, Garret Suen, Danilo D. Millen
Language: English
Subfield: Agronomy and Crop Science
Domain: Life Sciences
SDG: Zero hunger
Open Access status: gold
Estimated APC paid: $3,801
Award: G295657101
OpenAlex ID: W7128776706