In this study, 300 one-day-old male Ross 308 broiler chicks were divided into 6 groups to investigate the impact of various sources and levels of zinc (Zn) on the gut histomorphology of broiler chickens. The experiment was conducted in an open-sided housing system under high temperature conditions. This study used two sources of dietary zinc [(zinc oxide (ZnO) and zinc-methionine (Zn-Met)] and three levels of supplemental zinc (low: 0 mg/kg, adequate: 40 mg/kg, and high: 80 mg/kg). The study employed a completely randomized design with a 2 × 3 factorial arrangement. The results showed that the duodenal morphology was not affected by the zinc sources (P > 0.05). However, in the jejunum, birds that received adequate and high-zinc diets showed a significant increase in villus height (VH) and villus height to crypt depth (VH/CD) ratio (P < 0.05). The VH and the VH/CD ratio in the duodenum, as well as the VH, villus width, and the VH/CD ratio in the jejunum, were significantly greater in the Zn-met group compared to the ZnO group (P < 0.05). There was no observed interaction between the source and level of zinc on the measured intestinal mucosal morphology (P > 0.05). In conclusion, the present study has provided evidence supporting the beneficial effects of delivering Zn through the structure of Zn-Met at a concentration of 40 mg/kg of diet on the intestinal morphological features of broilers exposed to high ambient temperatures.
