Influence of Trace Mineral Sources and Levels on Growth Performance, Carcass Traits, Bone Characteristics, Oxidative Stress, and Immunity of Broiler

This study investigated the effects of reducing organic trace minerals below commercial inclusion levels and compared them with both low-dose and commercial levels of inorganic trace minerals, focusing on growth performance, carcass traits, tibia characteristics, oxidative stress (superoxide dismutase [SOD] and malondialdehyde [MDA]), and immune response (serum IgG) in broilers. A total of 384 one-day-old Ross 308 chicks were randomly assigned to three dietary treatments: (1) commercial-level inorganic trace minerals (ILI; Zn 100 ppm; Cu 15 ppm; Fe 100 ppm; Mn 80 ppm; Se 0.2 ppm; I 3 ppm); (2) low-level organic trace minerals (LLO; Zn 30 ppm; Cu 4 ppm; Fe 11 ppm; Mn 30 ppm; Se 0.225 ppm; I 3 ppm), and (3) low-level inorganic trace minerals (LLI; Zn 30 ppm; Cu 4 ppm; Fe 11 ppm; Mn 30 ppm; Se 0.2 ppm; I 3 ppm). Each treatment consisted of eight replicates with 16 birds per replicate, and diets were provided in two phases: starter (days 1–21) and grower (days 22–35). The results showed that the LLO group demonstrated a significantly improved feed conversion ratio (FCR) during the starter phase, 2.4% better than that of the ILI and LLI groups (p = 0.02). Additionally, filet and thigh muscle yields in the LLO group were higher by 11.9% (p = 0.03) and 13.9% (p = 0.02), respectively, compared to the ILI group. Other carcass traits, as well as pH and drip loss, were not significantly affected. However, tibia breaking strength at day 35 was 15.1% lower in the LLO group compared to the ILI group (p = 0.02). No significant differences were observed in oxidative stress markers or IgG levels among groups. This study demonstrated that reducing the inclusion level of inorganic trace minerals did not negatively affect broiler growth performance, whereas supplementation with low levels of organic trace minerals improved both growth performance and carcass quality.