Copper and L-arginine supplementation: impacts on laying hen health and productivity

This study investigated the impact of varying copper (Cu) and L-arginine (LA) supplementation levels on the productive performance, oxidative stability, cholesterol content, nutrient digestibility, immune system, and intestinal and liver morphology in laying hens. A total of 288 Hy-Line W-80 white laying hens (18-weeks-old) were assigned to a 2 × 3 factorial arrangement for 18 weeks. Diets included two levels of supplemental Cu (8 and 16 mg/kg) and three LA levels: the Hy-Line recommended level (RHL), 20% above RHL (LA20), and 40% above RHL (LA40). The experiment was a randomised complete block design with 6 treatments, each having 6 replicates of 8 birds per pen, for 18 weeks. Egg production in birds fed the Cu16 + LA20 diet increased between 23–35 weeks of age, compared to birds fed with Cu16 + LA40, Cu8 + RHL, and Cu16 + RHL (p < 0.05). Malondialdehyde (MDA) decreased in birds fed the Cu16 + LA40 diet, compared to those fed the Cu8 + RHL and Cu8 + LA20 diets (p < 0.05). The ratio of villus height to crypt depth (Villus: Crypt) improved in birds fed the Cu16 + LA20 and Cu16 + LA40 diets, compared to birds fed the Cu16 + RHL and Cu8 + LA20 diets (p < 0.05). Overall, supplementing laying hen diets with 16 mg copper/kg, combined with L-arginine at 20% or 40% above the recommended level, improved performance parameters, immune response, and nutrient digestibility. This approach also enhanced egg nutritional values, optimised intestinal morphology, boosted egg yolk oxidative stability, reduced cholesterol content, and provided protection against oxidative damage during storage.