No hints at glyphosate-induced ruminal dysbiosis in cows

Abstract

Glyphosate-based herbicides are among the most used non-selective herbicides worldwide and inhibit synthesis of aromatic amino acids in plants, bacteria, and fungi. Given the broad usage, controversies concerning potential effects of glyphosate on health and especially on gut microbiomes arose. For cattle, it has been proposed based on in vitro data that glyphosate has detrimental effects on the ruminal microbiome, which manifest as a specific inhibition of bacteria involved in fiber degradation and as an enrichment of specific pathogens. In the present study, glyphosate effects on the ruminal microbiome were analyzed in vivo using glyphosate contaminated feedstuffs with strong differences in dietary fiber and dietary energy content in order to reproduce the proposed detrimental glyphosate effects on the rumen microbiome. While significant impact of dietary factors on the ruminal microbiome and its products are pointed out, no adverse glyphosate effects on ruminal microbiome composition, diversity, and microbial metabolites are observed.

Effects of Different Formulations of Glyphosate on Rumen Microbial Metabolism and Bacterial Community Composition in the Rumen Simulation Technique System

“…Our results agree with previous RUSITEC studies, which observed only minor effects of glyphosate on the rumen bacterial population and no effects on the growth of pathogenic bacteria (Riede et al, 2016;Bote et al, 2019). In a recent in vivo study with dairy cattle, Billenkamp et al (2021) observed differences for only four taxa, which, however, appeared to be linked closer to experimental conditions than to glyphosate application. One of the formulations used in the present study, Roundup ® LB plus was also tested in a pig colon microbiota in vitro model, where also no effect on the microbial community composition was detected (Krause et al, 2020).…”

“…Typhimurium in the RUSITEC system (Bote et al, 2019). Schnabel et al (2017) did not observe adverse effects of a glyphosate-contaminated diet (intake up to 84.5 mg/d) on performance or energy balance of dairy cows, neither did this affect leucocytes or erythrocytes (Schnabel et al, 2020) or the rumen microbiome (Billenkamp et al, 2021).…”

Traditional and emerging Fusarium mycotoxins disrupt homeostasis of bovine mammary cells by altering cell permeability and innate immune function

“…In general, ruminants have been considered less susceptible than monogastric animals to mycotoxins due to ability of rumen to degrade mycotoxins into less toxic metabolites by rumen microbes ( Bertero et al., 2018 ; Fink-Gremmels, 2008 ; Rodrigues, 2014 ; Xu et al., 2020 ). However, ruminal biodegradation of mycotoxins could be influenced by antimicrobial properties of certain mycotoxins ( Bertero et al., 2020 ; Křížová et al., 2021 ; Wu et al., 2018 ), feed composition ( Upadhaya et al., 2010 ), and the consequent changes in the rumen environment characteristics (subacute ruminal acidosis, rumen dysbiosis and redox potential) ( Billenkamp et al., 2021 ; Huang et al., 2018 ), diseases ( Chen et al., 2021 ; Debevere et al., 2020 ; Nagaraja and Titgemeyer, 2007 ), and production stages ( Valgaeren et al., 2019 ). Collectively, these influences suggest that in some circumstances, mycotoxins could by-pass ruminal degradation and be distributed to different tissues via systemic circulation ( Debevere et al., 2020 ; Escrivá et al., 2017 ), and may therefore exert their toxic effects in different tissues.…”

Influences of glyphosate residues and different concentrate feed proportions in dairy cow rations during early gestation on performance, blood parameters, functional properties and DNA damage of blood cells in cows and their offspring

“…Pregnant cows investigated in the present study originated from a feeding trial under common practical conditions in agriculture as recently described by different authors [6,[18][19][20]. That trial indicated that 16 weeks of GLY exposure (average GLY exposure: 122.7 μg/kg BW/d GLY) did not lead to adverse effects on performance [6], serum metabolites [6,19], ruminal microbiome [18], liver health [19], hematology, functional properties of immune cells, oxidative status, and DNA integrity of blood cells in dairy cows in mid-lactation [20]. Different CFP affected most of analyzed parameters [6,[18][19][20].…”