Characterizing the link between the gastrointestinal tract microbiome, microbial metabolism, and host response in grain-finished cattle fed low-dose antimicrobials

Why this research is being done

Maladaptation to high grain diets increases an animal’s risk for BRD, liver abscesses, and other metabolic disorders. Combined, these disorders cost the beef industry in excess of 1 billion dollars (Rezac et al., 2014; Johnson and Pendell, 2017). While dietary antimicrobial drugs have offered a solution to subclinical diseases and other environmental stressors that decrease cattle growth, there is mounting evidence and concern that widespread use increases the selection for antibiotic-resistant bacteria and their transmission to the human population (Allen and Stanton, 2014). Nonetheless, the control of subclinical diseases, increased animal growth, and other benefits contribute to the overall efficiency of beef production and subsequent sustainability of the food chain. Complete removal of dietary antibiotics from beef cattle production is estimated to result in a 9% decrease in total production (Mathews, 2002). Therefore, it is critical that effective technologies are developed that can support maximum growth of cattle under various conditions. While ruminal health has received much attention, it is increasingly evident that the impact of high grain diets on other sections of the GIT substantially contribute to the overall pathophysiology of the disease (Sanz Fernandez et al., 2020). Indeed, the portal vein collects blood from the entire GIT and recent evidence suggests that a considerable number of bacterial endotoxins and liver abscess microbes arise from the post-ruminal GIT (Khafipour et al., 2009; Jennings et al., 2021; Pinnell et al., 2022). A more mechanistic understanding of how antimicrobial drugs work in post-ruminal regions of the GIT would enlighten mechanisms amenable to manipulation and will facilitate allied industry development of new strategies that target these changes.

Results

The microbiome richness was increased when antibiotics (Tylosin + Monensin/CTC) were fed compared to the control steers, suggesting a more diverse microbiome in feces over time. Tylosin + Monensin increased the abundance of beneficial bacteria across the gastrointestinal tract with major benefits noted in the rumen. Taken together, low dose antibiotics have a significant impact on the GIT microbiome, which could have implications for host health and feedlot cattle performance. This could be used as a guide for alternatives.

Conclusions

From this study we hope to determine how the changes in the microbiome affect the metabolites.

We also hope to understand how metabolites change gut physiology in the small intestine and lower GIT.

Contact information

Jon Schoonmaker jschoonm@purdue.edu | 765-494-4860