in vitro Effect of organic acid combinations on sporulation of Eimeria tenella

Abstract

Importance of the work: Organic acids show potential for inhibiting Eimeria tenella that causes chicken coccidiosis with diarrhea and weight loss; however, there is no available specific efficacy data.

Objectives: To evaluate citric acid and formic acid, both individually and combined, as well as a commercial product (known as Bluetec) for in vitro inhibition of E. tenella.

Materials and Methods: E. tenella oocysts were identified using morphology and polymerase chain reaction. The half maximal inhibitory concentration (IC50) for sporulation inhibition was determined by exposing oocysts to citric and formic acids at various concentrations. Trials consisted of citric acid, formic acid, their combination and Bluetec, with sporulation inhibition assessed after 24 hr and 48 hr by counting unsporulated and sporulated oocysts.

Results: The IC50 values were 4.33 mg/mL for citric acid and 2.40 mg/mL for formic acid. After 24 hr of incubation, the sporulation inhibition (SI) percentages were 2.95% for the 3% diclazuril (PC), 12.07% for citric acid, 8.50% for formic acid and 15.13% for the combination and 48 hr of incubation were 21.49%, 11.34% and 23.51%, respectively. Incubation for 48 hour resulted in a reduced sporulation percentage, indicating that the inhibition of sporulation was dependent on the duration of exposure. The SI percentages were  0% for distilled water, 7.96% for PC and 29.74% for Bluetec, highlighting significant differences among the tested items and suggesting a synergistic effect between citric and formic acids.

Main finding: Combining citric acid and formic acid, as well as using Bluetec effectively inhibited E. tenella sporulation. There was a notable synergistic effect of citric and formic acids, though its mechanism remained unclear. The most effective treatments were citric and formic acids with incubation for 48 hr and Bluetec with incubation for 24 hr. These organic acids could be utilized as food additives or disinfectants in poultry production.