Effects of dietary lactic acid supplementation on plasma ions and proteins levels in rainbow trout, Oncorhynchus mykiss

The aim of this study was to investigate the effect of adding lactic acid to the diet of rainbow trout on the plasma concentration of minerals and plasma proteins. For this purpose, 4 diets containing 0, 5, 10 and 20 g of lactic acid per kg of diet were prepared. 180 rainbow trout with an average weight of about 100 g were stored in 12 plastic tanks (150 L) and fed with each of the above diets (three tanks for each diet) for 8 weeks. The results showed that the addition of lactic acid to the diet had significant effects on the plasma concentrations of calcium, phosphorus, iron, copper, zinc, total protein and globulin (P <0.05). However, plasma total immunoglobulin and albumin were not affected by the addition of lactic acid to the diet (P> 0.05). All lactic acid concentrations significantly increased plasma calcium concentrations. Plasma phosphorus in 5 and 10 g of lactic acid treatments was higher than the control treatment. Plasma concentrations of iron in 10 and 20 g of lactic acid treatment, copper in 20 g of lactic acid treatment and zinc in 10 g of lactic acid treatment were significantly higher than the control treatment. Plasma total protein and globulin in 10 g of lactic acid treatment were higher than the control treatment. The results of this study show that the addition of lactic acid to the diet of rainbow trout has an effective role in increasing the concentration of plasma minerals and proteins. Accordingly, concentrations of 10-20 g / kg of lactic acid had the best results.