Traditionally,
antibiotic growth promoters (AGP) have been used in foodstock animals to reduce enteric
inflammation and maintain intestinal homeostasis, thus improving growth and performance. Due to increasing restrictions regarding the use of AGP however, precise and high throughput enteric
inflammation models and markers to search for effective alternatives are urgently needed. In this paper,
oral administration of
fluorescein isothiocyanate dextran (FITC-d, 3-5 kDa) and its passage into blood was used as a marker for tight junction permeability. In experiement 1, broilers were assigned to a control group, a group which received 24 h feed restriction (FR), or a group which received
dextran sodium sulfate (DSS) (0.75% in water for 5 d), and each group then underwent an oral gavage of
FITC-d 2.5 h before sample collection on d10.
FITC-d in serum and intestinal samples (duodenum and ceca) were found to be higher (P<0.05) after FR than in the DSS and control groups. In experiment 2, FR was evaluated for its effect on mucosal leakage and an oral dose of
FITC-d of 0.5, 1.1, or 2.2 mg/chick was used to measure the gastrointestinal tract (GIT) permeability at 6 d of age. The amount of
FITC-d remaining in the duodenal tissue of the control birds increased with dose, only the 1.1 mg
FITC-d/chick dose resulted in differences (P<0.05) between the control and FR groups. No differences were noted between the control and FR groups, regardless of
FITC-d dosage in cecal recovery of
FITC-d. Additionally, FR increased
FITC-d serum levels when compared to the control group and in a dose-dependent manner. Experiment 3 compared serum levels after administration of 0.55 and 1.1 mg/chick doses of
FITC-d in birds treated with FR, rye-based diet (RBD), and DSS. Intestinal sections were collected for
FITC-d recovery in the 1.1 mg dosage group. All
inflammation treatments significantly increased serum
FITC-d levels at both doses. Only FR resulted in increased (P<0.05)
FITC-d recovery from duodenum, ileum, and ceca. In conclusion, FR, DSS, and RBD affected GIT tight junction integrity, suggesting their value for enteric
inflammation models, and
FITC-d may be a good
indicator of permeability.