Influence of high inorganic selenium and manganese diets for fattening pigs on oxidative stability and pork quality parameters

Data are scarce regarding combined high Se and Mn supplementation in livestock diets, however, as Se and Mn are functionally related as cofactors of glutathione peroxidase (GPx) and Mn-superoxide dismutase (SOD), respectively, beneficial synergistic effects on oxidative stability of tissues may result. This experiment evaluated the effect of an oversupply of Se and Mn within European legal limits compared with recommendations on performance, oxidative stability of the organism and meat quality in a randomised complete block design. A total of 60 crossbred gilts were fed maize-barley-soya bean meal diets formulated in a 2x2 factorial approach with inorganic Se (0.2 v. 0.5 mg/kg Se dry matter (DM)) or inorganic Mn (20 v. 150 mg/kg Mn DM) from 31 to 116 kg BW. Se supplementation reduced feed intake, whereas high Mn diets impaired average daily gain (P<0.05). Qualitative carcass characteristics were impaired by Se and Mn predominantly in the semimembranosus muscle. Activity of GPx in liver was increased by high Se diets (P<0.05). Mn supplementation increased catalase (CAT) activity in liver, GPx in plasma and total antioxidative capacity (TAC) in muscle, whereas it decreased CAT activity in plasma (P<0.05). Cu/Zn-SOD in muscle showed higher activity in high-Se-low-Mn diets but lower activity when both high Se and Mn were combined (SexMn P<0.05). Mn supplementation increased Mn concentration in longissimus thoracis et lumborum, but simultaneously reduced Se concentration (P<0.05). Upon retail display, Mn increased lipid oxidation more pronouncedly (higher thiobarbituric acid reactive substances; P<0.05) than Se (P<0.10). Despite some positive effects (Mn increased TAC, Se increased GPx, Se and Mn increased tenderness), no synergistic effects of high Se and Mn diets or an overall beneficial impact on meat quality, especially during storage, could be observed. Including the negative effects on performance, feeding Se and Mn up to the maximum legal level cannot be recommended.