International Journal of Nano Dimension (Int. J. Nano Dimens.) Nano-Selenium affects on duodenum, jejunum, ileum and colon characteristics in chicks: An animal model Volume 10 (2019) Issue 2, April 2019 2024 02 07 Nano-Selenium affects on duodenum, jejunum, ileum and colon characteristics in chicks: An animal model EN Mansour Ahmadi Department of Animal Science, Ilam Branch, Islamic Azad University, Ilam, Iran Amir Ahmadian Department of Animal Science, Rasht Branch, Islamic Azad University, Rasht, Iran. Mohammadreza Poorghasemi Department of Animal Science, Science and Research Branch, Islamic Azad University, Tehran, Iran. Pavol Makovicky Department of Biology, Faculty of Education, J. Selye University, Komarno, Slovak Republic. Alireza Seidavi Department of Animal Science, Rasht Branch, Islamic Azad University, Rasht, Iran. Journal Article 2024 02 07 Selenium has many roles on the functioning of humans and animals. Chicks as animal model can play an important role to distinguish the role/function of selenium. The objective of the present study was to test the effect of variable doses of nano-selenium supplement on the chicken gastrointestinal tract. A total of 180 male Ross chicks were divided into six groups, with three replicates for each group and ten birds per replicate. Group 1 was the control group and was fed standard feeding for full experiment. Groups 2-6 were given variable doses of nano-selenium supplement from 1st-42nd days of age; Group 2 (0.1 mg/kg), Group 3 (0.2 mg/kg), Group 4 (0.3 mg/kg), Group 5 (0.4 mg/kg) and Group 6 (0.5 mg/kg). The results showed a decrease in the weights of small and large bowels with simultaneous increase in their lengths. Optimum doses of supplementary nano-selenium for bowel development are suggested.