Effects of Postbiotic Supplementation on Coccidiosis in Broiler Chickens Reared Under Different Stocking Densities

Background: Avian coccidiosis remains an important parasitic challenge in broiler production. Postbiotics have attracted attention as potential dietary interventions for improving intestinal health; however, their relationship with environmental Eimeria oocyst contamination under different stocking densities remains poorly understood. This study investigated the occurrence and abundance of Eimeria spp. oocysts in litter samples from broiler chickens receiving dietary postbiotic supplementation under different stocking densities. Methods: A total of 240 one-day-old Ross 308 broiler chickens were allocated to four treatment groups in a 2 × 2 factorial design involving two stocking densities (0.11 and 0.06 m²/bird) and two dietary postbiotic supplementation levels (0% and 0.3%). Each treatment comprised five replicate pens containing 12 birds each. The experiment lasted 42 days. Litter samples were collected from each pen on days 25, 35, and 40 and examined for Eimeria spp. oocysts using flotation and the McMaster counting technique. Results: Eimeria spp. oocysts were detected in five of 60 litter examinations (8.3%). Four positive samples were recorded on day 25, with counts ranging from 700 to 5600 oocysts per gram (OPG). All samples were negative on day 35. On day 40, the only positive sample (500 OPG) was detected in the unsupplemented low-density control group, whereas no oocysts were detected in either postbiotic-supplemented group. Overall, three positive examinations occurred under high stocking density and two under low stocking density. No consistent reduction in oocyst occurrence or abundance was observed in association with postbiotic supplementation. Conclusions: Dietary postbiotic supplementation was not associated with a consistent reduction in detectable litter Eimeria oocysts throughout the study. Although the absence of detectable oocysts in the supplemented groups on day 40 was noteworthy, the limited number of positive observations prevented definitive conclusions regarding postbiotic efficacy or stocking density effects. Further investigations involving more frequent sampling and complementary parasitological assessments are warranted.