Journal of Aquaculture Research & Development

Abstract

Effect of Different Levels of Dietary Calcium and Potassium on Growth Indices, Biochemical composition and Some Whole Body Minerals in Rainbow Trout (Oncorhynchus Mykiss) Fingerlings

Kalantarian SH *,Rafiee GH ,Farhangi M ,Mojazi Amiri B

Two completely randomized experimental designs were conducted to investigate the effect of different levels of dietary Ca (0.95%, 1.21%, 1.41% and 1.61%) and K (0.72%, 0.9%, 1.1% and 1.3%) on some growth indices, body biochemical composition and some whole body elements in rainbow trout fingerlings in a culture system. Tow basic diets with 0.95% Ca and 0.72% K were prepared and with CaCO3 for experiment І and K2CO3 for experiment ІІ, other dietary treatments were built. In initiation of each experiments, 25 pieces of rainbow trout fingerlings (12.18 ± 0.04 and 15.60 ± 0.05) introduced in each experimental units respectively, and were fed with dietary treatment ad libitum two times daily at 9:00 and 15:00 for a 8 week period. It was resulted that different levels of inorganic dietary-Ca in diets, had not significantly affected on growth factors (W1, WG, G%, SGR% day-1 and TGC), but different levels of inorganic dietary-K in diet had significantly affected (p<0.05) on these factors. FCR and survival rates did not show significant differences between the treatments in each experiment. In The first experiment, crude protein CP% and Ash% significantly increased and total lipid showed depletion with an increase in the dietary Ca (p<0.05). Change in inorganic dietary-Ca had significantly affected on Ca, P, Mn, Zn, Cu and Fe of whole body contents (p<0.05) and not affected the Mg and K of whole body. With increasing the inorganic dietary-K, diet with 0.9% total K, had significantly increased in CP% (p<0.05), however not significant differences between the trails in Ash% and total lipid% were observed. The Ca, K, P, Mg, Zn, Fe and Cu of whole body were significantly changed (p<0.05), and Mn had not significantly changed with increasing the inorganic dietary-K. Results were obtained in these studies, showed that, changes in amount of inorganic Ca in diets at the range of 0.95- 1.61% could not significantly affect on growth indices but dietary-K at the range of 0.72-1.3% affected the growth indices significantly (p<0.05). Significant effects on biochemical composition and some whole body minerals of cultured rainbow trout fingerlings with changes the dietary Ca and K were observed.