Japan Poultry Science Association Acta Medica Okayama 1346-7395 63 2026 Supplementation of 5-Aminolevulinic Acid Suppressed Body Weight Loss and Reduced Disease Severity During Eimeria tenella Infection in Broiler Chickens 2026010 EN Taqi Ahmad Hanif Laboratory of Animal Physiology, Graduate School of Environmental, Life, Natural Science and Technology, Okayama University Makoto Matsubayashi Department of Veterinary Science, Graduate School of Veterinary Sciences, Osaka Metropolitan University Toshimitsu Hatabu Laboratory of Animal Physiology, Graduate School of Environmental, Life, Natural Science and Technology, Okayama University This study aimed to evaluate the effects of 5-aminolevulinic acid (5-ALA) supplementation in broiler chickens infected with Eimeria tenella. To assess these effects, chickens supplemented with 20 ppm 5-ALA (5-ALA group) were compared with non-supplemented controls (control group). Sporulated E. tenella oocysts (2.0 × 103 oocysts per animal) were administered orally to 2-week-old broiler chickens. Body weight was measured weekly, and fecal samples were collected daily from 4 to 15 days post-infection (dpi). Fecal oocyst shedding was quantified using the sucrose flotation method. Cecal tissues were collected at 5 dpi for histopathological analysis and lesion scoring. The animals in the 5-ALA group exhibited significantly greater weight gain and milder clinical signs than those in the control group. Fecal oocyst shedding was highest at 7 dpi in both groups; however, the 5-ALA group exhibited significantly lower oocyst output than the control group. The total number of fecal oocysts shed during the acute infection period was significantly lower in the 5-ALA group than in the control group. Histopathological analysis revealed that although both groups exhibited epithelial hyperplasia and E. tenella schizonts in the cecal submucosa, inflammatory cell infiltration, cecal tissue damage, and histological lesion scores were significantly lower in the 5-ALA group than in the control group. These results suggest that 5-ALA supplementation may mitigate the clinical, parasitological, and histological effects of E. tenella infection in broiler chickens. No potential conflict of interest relevant to this article was reported.