Gorgan University of Agricultural Sciences and Natural Resources Poultry Science Journal 2345-6604 14 1 2026 01 01 The Effect of a Probiotic and a Prebiotic on Productive Performance, Egg Quality, Blood Chemistry and Intestinal Morphology of Laying Japanese Quails 75 90 7407 10.22069/psj.2025.23651.2325 EN Sosan Mohammadi Animal Science Department, College of Agriculture and Natural Resources, Razi University, Kermanshah, Iran Mehran Torki Animal Science Department, College of Agriculture and Natural Resources, Razi University, Kermanshah, Iran Maryam Darbemamieh Department of Plant Medicine, College of Agriculture and Natural Resources, Razi University, Kermanshah, Iran Journal Article 2025 05 10 The use of alternative feed additives, such as prebiotics, probiotics, or their combination (synbiotics), can help control pathogens and enhance the physiological performance of poultry. This study evaluated the effects of dietary probiotic and prebiotic supplementation on productive performance, egg quality, blood parameters, gut morphology, carcass traits, and cecal microflora in Japanese laying quails. A total of 196 laying quails, 22 weeks old, were randomly assigned to seven dietary treatments with seven replicates of four birds each for 56 days: basal control diet (C), 1% whey powder (W), whey powder + 1% dried mealworm (WM), whey powder + <em>Lactobacillus plantarum</em> (WB), whey powder + commercial probiotic (100 g/ton) (WP), mealworm + <em>Lactobacillus plantarum</em> + whey powder (MBW), and mealworm + commercial probiotic + whey powder (MPW). Egg production, feed conversion ratio, and most egg quality traits were not significantly affected by dietary treatments (P > 0.05). Feed intake was significantly reduced in the W, WB, MBW, and MPW groups compared with the control (P < 0.05). Gut morphology was significantly altered, with supplemented diets generally increasing duodenal villus length, villus width, and villus-to-crypt ratio compared with the control (P < 0.05). Whey supplementation increased serum protein, phosphorus, and triglyceride levels, whereas combining whey with probiotics and prebiotics mitigated the rise in triglycerides (P < 0.05). No significant differences were observed in carcass yield, internal organ weights, or cecal <em>Lactobacillus</em> and <em>Escherichia coli</em> counts (P > 0.05). In conclusion, dietary supplementation with prebiotic and probiotic sources, whether administered individually or in combination, improved specific gut morphological traits and modulated selected blood biochemical parameters without compromising performance or egg quality in laying Japanese quails. https://psj.gau.ac.ir/article_7407_0ba00848c3b9e403d6e844547bfbce79.pdf