Nonlinear dose-response evaluation of RenalMax supplementation in broiler chickens

This study evaluated the effects of RenalMax, a phytogenic blend containing nettle extract, sorbitol, ammonium chloride, and vitamins (B1, B2, B6, and C), on growth performance, serum biochemical variables, antioxidant status, and mineral metabolism in broiler chickens. A total of 400 one-day-old male Ross 308 broilers were randomly assigned to four treatments receiving 0, 0.25, 0.50, or 1.00 mL RenalMax/L drinking water, with five replicate pens of 20 birds per treatment, and were reared for 42 d RenalMax supplementation increased body weight gain and feed intake (P < 0.05), with the greatest response observed at 0.50 mL/L. Serum uric acid, creatinine, and blood urea nitrogen concentrations decreased (P < 0.001), whereas albumin and total protein concentrations increased. Supplementation was also associated with lower serum triglyceride, total cholesterol, low-density lipoprotein, alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, and malondialdehyde concentrations, together with higher high-density lipoprotein, total antioxidant capacity, glutathione peroxidase activity, and serum calcium and phosphorus concentrations (P < 0.05). Principal component analysis distinguished treatment groups based on the combined variation of growth performance, serum biochemical, antioxidant, and mineral variables. Dose-response analyses using polynomial and segmented regression models identified nonlinear responses for several variables, with model-estimated optima generally occurring between 0.5 and 0.6 mL/L within the evaluated supplementation range. Overall, RenalMax supplementation was associated with favorable changes in growth performance and multiple serum biochemical, antioxidant, and mineral-related variables in broiler chickens, although the estimated optimal supplementation level should be confirmed under commercial production conditions.