OBJECTIVE: This study aimed to examine the impact of cupric citrate on broilers and compare it with the copper sulfate groups and a control group. METHODS: A total of 360 1-day-old Ross 308 broilers were randomly assigned into 5 groups, each with 6 replicates of 12 broilers per treatment. The control group was fed a basal diet without any copper supplementation. In contrast, the other groups received basal diets supplemented with either 50 mg/kg (CS-50) or 100 mg/kg (CS-100) of copper in the form of copper sulfate, or 50 mg/kg (CC-50) or 100 mg/kg (CC-100) of copper in the form of cupric citrate, for a period of 42 days. RESULTS: The results showed that copper supplementation affected the average daily gain (ADG) from day 1 to 21 (p = 0.026) and day 1 to 42 (p = 0.025) in a source-dependent manner. Copper source also influenced the energy digestibility (p = 0.004), with the CC-100 being the most effective treatment. Notably, birds in the CC-100 groups had significantly reduced concentrations of Escherichia coli (p<
0.05) in the cecum, and the Lactobacillus in the ileum, compared to the control group. Dietary copper supplementation also increased the pH in the duodenum (p<
0.05) irrespective of the sources and levels. In addition, the source of copper affected the activities of ceruloplasmin (p = 0.014) and CuZn superoxide dismutase (p = 0.025) in the serum, with the CC-100 group showing the highest levels of both enzymes. CONCLUSION: Copper supplementation generally improves the growth, nutrient utilization, intestinal microflora, gastrointestinal pH, and antioxidant defences of broilers. Moreover, cupric citrate is as effective as copper sulfate even at equal or lower concentrations.