Effects of Bacitracin Zinc and Lactobacillus reuteri on Growth Performance and the Expression of Immune Modulators in Guinea Fowl Broilers

Alexis T Pigg, Tennessee State University


Antibiotic growth promoters (AGPs) are linked to antibiotic resistant pathogens. Therefore, alternatives to AGPs are being sought, with probiotics being potential alternatives. Antibiotics and probiotics modulate immune status in the gastro-intestinal tract of poultry. Additionally, endogenous retroviruses (ERVs) have been implicated in initiating immune inflammatory responses, measurable by the expression of interferons. Expression of cytokines and ERVs are influenced by many factors. Antibiotics and probiotics may regulate the expression of interferons, ERVs, and other genes linked to inflammation. The aims of this study were, therefore, to classify the composition of ERVs flanking interferon genes and to clarify the modulation of interferon expression by antibiotics and probiotics in guinea fowl. 320 one-day-old French guinea fowl keets were randomly assigned to four dietary treatments (basal corn-soy (BCS) control diet, BCS+ 50mg/kg bacitracin zinc, BCS+ 100mg/kg L. reuteri and BCS+100mg/kg of soy protein) for a four week experiment. Bird performance was evaluated once weekly. Tissue from the spleen and small intestine were excised for gene expression analysis via RT-PCR. Bioinformatics analysis was conducted on the current Numida meleagris genome assembly to screen for ERVs within 1Mbp regions flanking interferon genes. Gene expression analysis by RT-PCR was performed to measure expression levels of IFN-γ and IFN-Like. Animals fed basal diets supplemented with bacitracin zinc, L. reuteri, and soy protein demonstrated significantly lower feed consumption and improved feed conversion. Birds fed the soy protein and L. reuteri rations performed statistically similarly, with the L. reuteri treatment exhibited better feed efficiency numerically. Three types of ERVs flanking four interferon genes were identified via bioinformatics analysis: ERVL, ERV1, and ERVK (Type II and Type III ERVs). Modulation of IFN-γ and IFN-Like expression was exhibited by the antibiotic and probiotic treatments and is correlated to animal performance. And ERVL was found in proximity to IFN-Like, which was significantly upregulated by the probiotic treatment. Therefore, antibiotics and probiotics may interact with genomic elements to modulate interferon expression which consequently affects animal growth and performance in guinea fowl.

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Recommended Citation

Alexis T Pigg, "Effects of Bacitracin Zinc and Lactobacillus reuteri on Growth Performance and the Expression of Immune Modulators in Guinea Fowl Broilers" (2020). ETD Collection for Tennessee State University. Paper AAI13426276.