Comparison of intestinal permeability methods in broilers over a 6-week growth period

Authors: WIERSEMA, MADDISON - Iowa State University; Kerr, Brian; KOLTES, DAWN - Iowa State University

Submitted to: Poultry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/28/2023
Publication Date: 8/4/2023
Citation: Wiersema, M.L., Kerr, B.J., Koltes, D.A. 2023. Comparison of intestinal permeability methods in broilers over a 6-week growth period. Poultry. 2(3):383-394. https://doi.org/10.3390/poultry2030028.
DOI: https://doi.org/10.3390/poultry2030028

Interpretive Summary: The intestine is a selectively permeable tissue which controls the passage of water, nutrients, electrolytes, and other essential ions into the body. Factors such as age, diet, shifts in intestinal microbiota, infection, disease, environment, and stress can impact the intestinal barrier, leading to increased permeability. Increasing the rate of non-mediated passive diffusion or intestinal permeability, through or between intestinal epithelial cells, can lead to decreased growth performance, compromised health, and increased skeletal diseases in farm animals. Therefore, identifying a consistent method to determine intestinal permeability in non-disease states that can be used on commercial farms is critical for understanding and improving intestinal health and overall performance of poultry. The study conducted herein compared serum concentrations of fluorescein isothiocyanate-dextran, mannitol, lactulose, and the ratio of lactulose to mannitol in broilers to determine intestinal permeability as an indicator of intestinal health. The data show there were significant increases in fluorescein isothiocyanate-dextran and lactulose with fasted compared to fed states and when the sugar was provided compared to the control, but this was the observation with mannitol. This information shows that lactulose may be of promise for use in showing differences in intestinal permeability in a commercial setting and may be of use to nutritionists at universities, feed companies, poultry production facilities on their approach to evaluating stress effects on intestinal function and permeability.

Technical Abstract: The need to understand intestinal health is of increasing importance; however, adoption of these methods in poultry has been slow due to the lack of urine excretion. The objective of this study was to compare intestinal permeability assays using serum collected from poultry under a known stressor. Two independent trials were conducted comparing the two commonly used methods (fluorescein isothiocyanate-dextran (FITC-D) method and lactulose/mannitol (LMS) dual sugar method). Each trial had 40 pens of broilers split across 2 fed states (fed or fasted for 12 hours) and 4 sugar-gavaging treatments (no sugar, FITC-D, LMS, FITC-D+LMS). Four birds from each pen were sampled at 14, 28, and 42 d of age. Serum FITC-D was determined using fluorescent spectrophotometry while mannitol and lactulose concentrations were determined using ion chromatography. Data were analyzed using PROC Glimmix. Fed state, sugar treatment, age, and all 2- and 3-way interactions were included as fixed effects. Trial was included in the model as a random effect with pen included as a repeated effect. Serum lactulose and FITC-D increased in fasted compared to fed birds (P<0.006). Mannitol, which was expected to be similar across fed and fasted, was elevated in fed compared to fasted birds (P<0.001). The elevated concentrations of mannitol in fed birds suggest additional elutants in the serum samples. Therefore, under these conditions, mannitol, and its ratio with lactulose, are not appropriate methods for measuring intestinal permeability in poultry based on the analytical methods used herein. Serum lactulose and FITC-D concentrations were elevated in birds gavaged with these sugars and serum concentration of both sugars decreased at d 28 compared to d 14 and 42 (P<0.003). FITC-D had a significant interaction for the sugar by fed state (P<0.05). Serum lactulose concentrations were significant for all interactions with elevated serum lactulose concentrations in broilers provided lactulose and fasted (P<0.001). Birds that did not receive lactulose had very low to undetectable concentrations of lactulose. This reduced background for the detection of serum lactulose increases the ability to detect small changes in intestinal permeability making lactulose a potential serum biomarker for intestinal permeability in poultry.