Impacts of increasing challenge of E. maxima on gut integrity and gene expression of nutrient transporters in broiler chickens

Authors: TENG, PO-YUN - University Of Georgia; CHOI, JANGHAN - University Of Georgia; TOMPKIN, YUGOU - University Of Georgia; Lillehoj, Hyun; KIM, WOO KYUN - University Of Georgia

Submitted to: International Journal of Parasitology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/26/2021
Publication Date: 6/9/2021
Citation: Teng, P., Choi, J., Tompkin, Y.H., Lillehoj, H.S., Kim, W. 2021. Impacts of increasing challenge of E. maxima on gut integrity and gene expression of nutrient transporters in broiler chickens. International Journal of Parasitology. https://doi.org/10.1186/s13567-021-00949-3.
DOI: https://doi.org/10.1186/s13567-021-00949-3

Interpretive Summary: Coccidiosis is a major enteric disease of poultry that costs poultry industry more than 14 billion USD annually. Ability to control coccidiosis without antibiotics is a major challenge that industry is facing today. Several different parasite strains belonging to Eimeria are responsible for coccidiosis which has a significant negative impact on gut health and decreases optimum nutrient utilization. In this study scientists at the University of Georgia, in collaboration with ARS scientists in Beltsville, demonstrated various aspects of intestinal health that are negatively affected by parasite infection, especially the effect of infecting doses of Eimeria parasites on intestinal health. The results showed that there is a linear reduction of growth performance and gut integrity with increasing infecting dose of E. maxima oocysts. At high dose infection level, the expression of biomarkers associated with nutrient transporters and tight junction were significantly affected. In conclusion, growth performance and several gut health biomarkers were linearly regulated in response to the increasing doses of Eimeria parasites. These findings will enhance our understanding of changes in the key functional aspects of gut health associated with coccidiosis and the results will facilitate novel treatment method to address infection-related gut health issues in raising commercial chickens.

Technical Abstract: The study was conducted to investigate the impacts of graded severity of E. maxima infection on growth performance and gut health of broiler chickens. Four levels of E. maxima-challenged treatments were used in the study, including a non-challenged control group (Control), a low challenge dose (Low, 12,500 oocysts of E. maxima), a medium challenge dose (Medium, 25,000 oocysts of E. maxima), and a high challenge dose (High, 50,000 oocysts of E. maxima). There were 8 replicated cages per treatment, with 12 birds raised in each cage. Birds in the challenged groups were gavaged with corresponding doses of oocysts on d 14. Gastrointestinal permeability was measured by fluorescein isothiocyanate dextran on 5-day post-infection, whereas intestinal morphology, gene expression of nutrient transporters, and tight junction proteins were determined on 6-day post-infection. The results demonstrated a linear reduction of growth performance, villi height of the small intestine, and gut integrity with increasing challenge doses of E. maxima. Moreover, graded levels of infection linearly regulated the expression of nutrient transporters and tight junction proteins. The linear up-regulation of Claudin 1, Cationic amino acid transporter, Glucose transporter 1, and L-type amino acid transporter genes was associated with increased infection severity. Furthermore, the greater challenge doses linearly reduced gene expression of Occludin, Zonula occludens 1, Claudin 2, and all nutrient transporters located on the brush border membrane. In conclusion, growth performance and several gut health biomarkers were linearly regulated in response to the increase of E. maxima infection. In addition to understanding of changes in the key functional elements in the gut related to the severity of E. maxima infection, the study provided new evidence for future studies to decide an appropriate dose of E. maxima as a suitable challenge model in evaluating new nutritional strategies on gut health of modern chickens in coccidiosis.