Marta S Silva1, P Antony Jesu Prabhu2, Robin Ørnsrud3, Veronika Sele2, Saskia Kröckel4, Jens J Sloth5, Heidi Amlund6. 1. Institute of Marine Research, P.O. Box 1870 Nordnes, 5817 Bergen, Norway; Department of Biological Sciences, University of Bergen, P.O. Box 7803, 5020 Bergen, Norway. 2. Institute of Marine Research, P.O. Box 1870 Nordnes, 5817 Bergen, Norway. 3. Institute of Marine Research, P.O. Box 1870 Nordnes, 5817 Bergen, Norway. Electronic address: Robin.Ornsrud@hi.no. 4. Skretting Aquaculture Research Centre, P.O. Box 48, 4001 Stavanger, Norway. 5. National Food Institute, Technical University of Denmark, Kemitorvet, Bygning 202, 2800 Kgs. Lyngby, Denmark. 6. Institute of Marine Research, P.O. Box 1870 Nordnes, 5817 Bergen, Norway; National Food Institute, Technical University of Denmark, Kemitorvet, Bygning 202, 2800 Kgs. Lyngby, Denmark.
Abstract
BACKGROUND: The determination of dietary mineral solubility is one of the main steps in the evaluation of their availability for a given species. METHODS: This study proposed an in vitro digestion method (acidic and alkaline hydrolysis). The method was applied to evaluate the solubility of inorganic and organic forms of zinc (Zn), selenium (Se) and manganese (Mn) in salmonid diets. An inorganic mineral (IM) diet was supplemented with zinc sulphate, sodium selenite and manganous sulphate and an organic mineral (OM) diet was supplemented with zinc chelate of glycine, l-selenomethionine and manganese chelate of glycine. RESULTS: The solubility of Zn was similar in both diets tested. The amount of soluble Zn was low in the acidic hydrolysis (3-8%) and lower in the alkaline hydrolysis (0.4-2%). The solubility of Se was higher in the OM diet (7-34%) compared with the IM diet (3-12%). Regarding Mn, after the acidic hydrolysis the solubility was higher in the IM diet (6-25%) than the OM diet (4-17%). The in vitro solubility were compared with in vivo availability of Zn, Se and Mn. Data obtained for solubility (%) of Zn, Se and Mn was lower when compared with apparent availability (%) of Zn, Se and Mn. CONCLUSION: Data obtained demonstrated that solubility of Zn, Se and Mn was influenced by the mineral chemical form supplemented to the diet and by the gastrointestinal environment. The solubility of Zn, Se and Mn was not comparable with the apparent availability of Zn, Se and Mn. Nevertheless, the effect of the chemical form of the minerals was similar for the solubility of Zn, Se and Mn and the apparent availability of Zn, Se and Mn. Considering the overall results of this study, the in vitro method could replace some of the in vivo studies for a qualitative evaluation but not for a quantitative evaluation.
BACKGROUND: The determination of dietary mineral solubility is one of the main steps in the evaluation of their availability for a given species. METHODS: This study proposed an in vitro digestion method (acidic and alkaline hydrolysis). The method was applied to evaluate the solubility of inorganic and organic forms of zinc (Zn), selenium (Se) and manganese (Mn) in salmonid diets. An inorganic mineral (IM) diet was supplemented with zinc sulphate, sodium selenite and manganous sulphate and an organic mineral (OM) diet was supplemented with zinc chelate of glycine, l-selenomethionine and manganese chelate of glycine. RESULTS: The solubility of Zn was similar in both diets tested. The amount of soluble Zn was low in the acidic hydrolysis (3-8%) and lower in the alkaline hydrolysis (0.4-2%). The solubility of Se was higher in the OM diet (7-34%) compared with the IM diet (3-12%). Regarding Mn, after the acidic hydrolysis the solubility was higher in the IM diet (6-25%) than the OM diet (4-17%). The in vitro solubility were compared with in vivo availability of Zn, Se and Mn. Data obtained for solubility (%) of Zn, Se and Mn was lower when compared with apparent availability (%) of Zn, Se and Mn. CONCLUSION: Data obtained demonstrated that solubility of Zn, Se and Mn was influenced by the mineral chemical form supplemented to the diet and by the gastrointestinal environment. The solubility of Zn, Se and Mn was not comparable with the apparent availability of Zn, Se and Mn. Nevertheless, the effect of the chemical form of the minerals was similar for the solubility of Zn, Se and Mn and the apparent availability of Zn, Se and Mn. Considering the overall results of this study, the in vitro method could replace some of the in vivo studies for a qualitative evaluation but not for a quantitative evaluation.