eng Rovedar Journal of World’s Poultry Science 2980-7999 2024-09-29 3 3 33 41 10.58803/jwps.v3i3.38 40 Evelyn Ngwa 0 https://orcid.org/0009-0004-4444-9261 Katte Brigitte 1 https://orcid.org/0000-0001-7857-8636 Ebile Dayan Agwah 0 https://orcid.org/0009-0003-1400-6630 Edie Nounamo Langston Wilfried 0 https://orcid.org/0000-0002-3299-8966 Teguia Alexis 0 https://orcid.org/0000-0001-7857-8636 Animal Production and Nutrition Research Unit, Department of Animal Sciences, Faculty of Agronomy and Agricultural Sciences, University of Dschang, PO Box: 70 Dschang, Cameroon Animal Physiology and Health Research Unit, Department of Animal Sciences, Faculty of Agronomy and Agricultural Sciences, University of Dschang, PO Box: 188 Dschang, Cameroon Introduction: The reduced susceptibility of microorganisms to synthetic preservatives and consumer's demand for high-quality, and minimally processed green-label foods urged researchers to focus more on natural preservatives. This study aimed to evaluate the in vitro and in sacco antifungal activities of Ageratum conyzoides leaves essential oil (EO) against Aspergillus flavus, Aspergillus niger, Aspergillus terreus, and Penicillium spp. in poultry feed. Materials and methods: The poultry feed was stored for 30 days. The dilution plate method was then used to isolate the fungi present in the feed. The leaves of Ageratum conyzoides were collected and their EO was extracted using Steam distillations. The in vitro antifungal activity of EO (2.3; 3.4; 4.0; 4.5; 5.1 and 5.7; [µl/cm2]) was tested using the modified method, against the above fungi species during a 4-week of research. In sacco antifungal Screening of EO (5.7; 5.1; 4.5 and 4.0μl/Kg of feed) was done on poultry feed and kept for 10, 20, and 30 days. Results: The most frequently isolated fungi in poultry feed was Penicillium spp. (84.07%). The smallest in vitro colony diameters were recorded by Aspergillus niger with 4µl of EO. The highest level of fungi growth reductions was recorded at 2.3µl of EO. Following 20 days of storage, 4.0µl of EO/kg of feed was shown to completely (100%) inhibit Aspergillus niger and Aspergillus terreus in the Sacco research. At 30 days of storage, there was no contamination in poultry feed especially in aspects of Aspergillus flavus, Aspergillus niger, and Aspergillus terreus. Penicillium sp. contamination in poultry feed decreased as the EO concentration increased. Conclusion: The results of the current study indicated that Ageratum conyzoides leaves essential oil at the level of 4.0µl of EO/kg of feed had the highest prevention effects on fungus growth. https://jwps.rovedar.com/index.php/JWPS/article/view/38 Antifungal activity Fungi count Ageratum coyzoides Leaves essential oil Poultry feed Preservative effect