Bone development of broiler chickens supplemented with chondroitin sulfate and manganese

Musculoskeletal disorders in broiler chickens are often related to immature connective tissue. This study aimed to evaluate the effects of dietary supplementation with chondroitin sulfate (CS) and manganese (Mn) on performance, bone quality, and the optimal CS:Mn ratio for skeletal development in broilers. A total of 1152 male Cobb chicks were reared for 47 days in a completely randomized 4 × 3 factorial design comprising four CS levels (0.00, 0.06, 0.12, and 0.18 % w/w) and three Mn levels (0, 40, and 80 mg/kg), resulting in 12 treatments with eight replicates of 12 birds each. Supplementation with CS and Mn did not affect (P > 0.10) feed intake, body weight, weight gain, bone mineral content, bone mineral density, phosphorus and manganese levels, ash content, absolute bone weight, or diaphyseal perimeter of the tibiotarsus. A significant interaction between CS and Mn levels was observed for feed conversion (FC), which increased linearly with Mn inclusion in diets lacking CS (P = 0.003). In diets without Mn, CS levels exhibited a quadratic effect on FC (P = 0.003). Flock viability and productive efficiency index increased linearly with increasing CS inclusion. A significant CS × Mn interaction was also observed for maximum bone breaking strength, with a linear decrease with increasing Mn in diets containing 0.12 % CS (P = 0.019). CS had a quadratic effect on the Seedor index, bone area, and morphometric traits of the proximal and distal tibiotarsus, with 0.06-0.12 % CS yielding optimal outcomes. Mn supplementation showed quadratic effects on bone area (P = 0.09) and calcium content (P = 0.005), with peak values at 40 mg Mn/kg. The results suggest that supplementation with CS and the inclusion of 40 mg Mn/kg in broiler diets could be used as a nutritional strategy to improve tibiotarsal bone quality, particularly morphometric attributes, calcium content, and breaking strength. Furthermore, CS supplementation may contribute to reducing mortality and improving productivity metrics in broilers.