High Dietary Organic Iron Supplementation Decreases Growth Performance and Induces Oxidative Stress in Broilers

SIMPLE SUMMARY: Iron (Fe) is an essential trace element nutrient that plays a vital role in metabolic processes, such as oxygen transportation and electron transfer during respiration. However, exposure to high levels of dietary Fe can have negative effects on growth performance and antioxidant function in broilers. Organic Fe has a considerably higher bioavailability than inorganic Fe. To evaluate the safety of Fe chelates with lysine and glutamic acid (Fe–LG) in broilers, we investigated the effects of high concentrations of dietary Fe–LG on serum biochemical parameters, antioxidant status, and duodenal Fe transporter mRNA expression in broilers. A supplementation of 800 mg/kg Fe induced kidney function injury and liver oxidative stress in broilers, and decreased duodenal Fe transporter mRNA expression. Hence, this study demonstrated that high levels of Fe–LG negatively affect broiler health, and proposed a maximum supplemental dose of Fe–LG in broiler diet as a nutritional feed additive. ABSTRACT: Although Iron (Fe) is an essential nutrient that plays a vital role in respiratory processes, excessive Fe in the diet can affect the health of broilers. We investigated the effects of diet supplemented with high levels of iron chelates with lysine and glutamic acid (Fe–LG) on the growth performance, serum biochemical parameters, antioxidant status, and duodenal mRNA expression of Fe transporters in broilers. A total of 800 1-day-old male Arbor Acres broilers were assigned to 5 groups, with 8 replicates each. Broilers were fed a corn–soybean meal basal diet or basal diets supplemented with 40, 80, 400, or 800 mg Fe/kg as Fe–LG for 6 weeks. The body weight (BW) was increased in the 80 mg Fe/kg treatment group, but decreased in the 800 mg Fe/kg treatment group on day 21. During days 1–21, compared with the control group, the supplementation of the 80 mg Fe/kg increased the average daily gain (ADG) and average daily feed intake (ADFI); however, the supplementation of the 800 mg Fe/kg group decreased the ADG and increased the FCR in broilers (p < 0.05). The heart, liver, spleen, and kidney indices were reduced in the 800 mg Fe/kg treatment group (p < 0.05). The supplementation of the 800 mg Fe/kg group increased the serum aspartate aminotransferase activity and the levels of creatinine and urea nitrogen on day 42 (p < 0.05). The broilers had considerably low liver total superoxide dismutase activity and total antioxidant capacity in the 800 mg Fe/kg treatment group (p < 0.05). Serum and liver Fe concentrations were elevated in the 400 and 800 mg Fe/kg treatment groups, but were not affected in the 40 and 80 mg Fe/kg treatment groups. The duodenal Fe transporters divalent metal transporter 1 (DMT1) and ferroportin 1 (FPN1) were downregulated in the Fe–LG treatment groups (p < 0.05). We conclude that a high dietary supplement of 800 mg Fe/kg in broilers leads to detrimental health effects, causing kidney function injury and liver oxidative stress.