University of Guilan Caspian Journal of Environmental Sciences 1735-3033 21 2 2023 04 01 Influence of using probiotic on the productivity and morphometry of the organs in the visceral cavity of broiler chicks 431 437 6537 10.22124/cjes.2023.6537 EN Ziad Ahmad Alabdallah Department of Anatomy-Histology and Embryology, Al Furat University, Deirez-Zor, College of Veterinary, Syria Aleksandr Alekseevich Nikishov Peoples Friendship University of Russia (RUDN University) Moscow, Miklukho-Maklaya Street, Russia Cueva Jimenez Jhonn Lenon Peoples Friendship University of Russia (RUDN University) Moscow, Miklukho-Maklaya Street, Russia Mario Leonardo Ortiz Manzano University of Armed Forces – ESPE, Ecuador Journal Article 2023 05 14 Probiotics are feed additives that have gained popularity in poultry. They are one of the more universal feed additives and can be easily combined with other additives.<strong> </strong>This study was designed<strong> </strong>to evaluate the impact of including recommended doses of probiotics and growth-promoting antibiotics in concentrated foods on productivity and gut health in broilers.<strong> </strong>Six hundred one-day-old unsexed broiler chicks (Ross 308 strain) were used in this study. They were divided into three groups (40 chicks per group). Group T₀ received balanced feed with growth stimulating antibiotic (Zinc Bacitracin), while group T₁ received balanced diet (no growth stimulating antibiotic) + probiotic (<em>Bacillus subtilis</em> sp.; 1.6 × 10⁹ CFU g^-1) at an inclusion rate of 500 g ton^-1. Group T² was fed the basal balanced diet with a growth-stimulating antibiotic (Zinc Bacitracin) and a probiotic (<em>Bacillus subtilis</em> sp.).<strong> </strong>Statistical analysis and processing the material were performed using the data analysis package "MS Excel 2010" and the program "Statistics for Windows".<strong> </strong>In<strong> </strong>this study, we assessed the effect of supplementation of probiotics and acidifiers as well as their combination on broiler live body weight, net carcass, along with dressing percentage, the weight of the internal organs, relative bowel length (small intestine length, large intestine length, caecum length, and fabric bag length) and weight of broiler cuts breast. The outcomes revealed a difference between the control and other treatment groups which was statistically significant (p < 0.05). The ratio of villus height to crypt depth and villus height in the duodenum and ileum were both raised (p < 0.05) by the addition of either probiotics or synbiotics. https://cjes.guilan.ac.ir/article_6537_dc36236eb4611e102cb1eabde9583ebb.pdf