The effects of Beta Glucan from Cordycep Mushrooms Diets on Swine Microbiota Composition

Modern day agricultural practices are shifting to less antibiotic usage in food animal production due to scientific, socio-political, and consumer concerns. However, the need to maintain healthy livestock while preventing the onset of pathogenic outbreaks still needs to be kept at a high standard; otherwise, the industry and the consumers are at biological and financial risks. One method to move away from antibiotics but still maintain animal health, is to look at alternatives that promote natural immunity and animal gut health. Recent studies have shown that Beta-glucans encourage the production of cytokines and chemokines which activate macrophages and increased sensitivity to pathogenic antigens in the host. This study focused on using varying diets with differing levels of Beta-glucans from Cordyceps-based mushroom powders to post-weaned piglets and observe the diversity and compositional changes in their intestines over 5 weeks of feeding. Throughout this project, sixty piglets were assigned to 35 pens with one barrow and one gilt placed in each pen. For the duration of the study, each pen was subject randomly to one of five different dietary treatments: a negative control diet without any antimicrobial additives, a positive control diet with 55 ppm Carbadox (antibiotic) added, a 300 ppm Cordyceps-based mushroom powder diet, 600 ppm Cordyceps-based mushroom powder diet, and a step-down diet containing 900, 900, 450, 300, and 150 ppm Cordyceps-based mushroom powder diet for weeks 1, 2, 3, 4, and 5 respectively. Body weight, average daily gain, average daily feed intake, and feed conversion values were recorded on day 0, 7, 14, 21, and 28 of the experiment. Fecal samples were obtained after 5 weeks on the treatment diets. After the endpoint sample collection, metagenomic bacterial community composition was determined using 16S rRNA gene sequencing, and QIIME2-based bioinformatic analysis. Alpha diversity was calculated via Faith phylogenetic diversity for both richness and evenness metrics. Results concluded that there are no significant differences amongst fecal samples between treatments for both richness-based and evenness-based metrics. Additionally a Kruskal-Wallis (pairwise) comparison between the antibiotic dietary treatment and the mushroom dietary treatments had a p-value slightly below the significance threshold of 0.05, indicating that the slight difference is not considerable enough for impact on the microbial diversity. Additionally, a weighted and unweighted Unifrac distance Emperor plots were created to test for beta diversity. The permanova pairwise statistical tests graph the respective distance for the PCoA plots, and similarly to alpha diversity, the results indicate no significant differences between the Carbadox and Beta -Glucan diets. It was expected for there to be an increase in Lactobacilli and Bifidobacteria. Previous studies have shown that Beta -glucans are present in these various bacteria and are capable of influencing gut microbiota. However, from the study, there were no discernable differences between the different treatment groups. There may have been potential factors in the experimental design that could be changed or revisited such as finding sources of error in the study from sample collection to wet lab procedures. While the study concludes not enough significant differences from the effects of Beta-glucans, there can be many improvements made to experimental design and research preparation to challenge and reproduce similar procedures from other conducted studies.