Influence of copper level and source on performance, tissue accumulation, and faecal excretion in fattening pigs.

Copper (Cu) supplementation is essential in pig nutrition; however, its effects on performance, trace element accumulation in edible tissues, and environmental excretion require careful evaluation. In the present study a total of 24 male, castrated fattening pigs of two different hybrid mast lines (11 weeks of age) were divided according to their initial body weight (25.8 ± 3.5 kg) into four groups. Pigs were fed for 14 weeks a complete feed supplemented with Cu covering a range between the recommended Cu supplementation and the permissible European maximum level (i.e. 5, 15, and 25 mg/kg complete feed). Two different Cu sources were used: Cu sulphate (CuSO₄) and glycine-Cu chelate hydrate (Cu-Gly). The aim of the trial was studying the influence of the different Cu levels and sources on growth performance, Cu transfer to edible tissues (muscle, liver, kidney, blood) and faeces, as well as the concentration of other trace elements, including iron (Fe), zinc (Zn) and manganese (Mn) in tissues of fattening pigs. Performance parameters, including average daily gain (ADG) and feed conversion ratio (FCR), showed a dependency with respect to the pig breed, whereas Cu content and Cu sources showed no influence. Copper concentrations in the liver, kidney, muscle, and blood serum remained constant across groups. Faecal Cu excretion increased proportionally with dietary Cu levels, with higher excretion observed for the organic Cu source at 15 mg/kg as compared with inorganic source at similar level. The results show, that Cu levels up to the maximum level of 25 mg/kg complete feed are not necessary to achieve good growth performance in healthy fattening pigs. The unaffected Cu concentrations in liver, muscle, kidney, and blood, as well as increased faecal excretion with increasing Cu level in the feed, indicate an adequate supply and homoeostatic regulation of Cu. In addition, a reduced use of Cu in pig fattening will help to reduce Cu emission into the environment.