Comparison of organic and inorganic microminerals in all plant diets for Nile tilapia Oreochromis niloticus

An 8-week feeding trial was conducted to evaluate the production performance of all male Nile Tilapia (Oreochromis niloticus) fed diets supplemented with increasing levels of trace mineral premixes (copper, selenium, zinc, iron, manganese) from inorganic (I) and organic (O) sources. A practical trace mineral basal diet was developed using only plant ingredients. Nine experimental diets were prepared from the basal formula by adding graded levels of inorganic or organic trace mineral premixes to deliver 0 (control diet), 0.5, 1.0, 2.0 or 4.0 times the micromineral requirement for tilapia as stated in the NRC (2011). Juvenile Nile tilapia (initial weight 7.13 ± 0.24 g) were randomly stocked into 50-L aquaria at 25 fish per aquarium. Each of the nine treatments was replicated five times except treatment 8 (I-4) with four replicates. According to the results of our study, there were no significant effects of trace mineral premix levels and sources on the growth performance, survival rate and whole body proximate composition of Nile tilapia (P > .05). However, the trace mineral concentrations in the whole body and fillet were significantly influenced by the dietary levels of premixes. With the exception of selenium, there were no major differences in the micromineral contents in the fillet between fish fed the organic or inorganic sources of microminerals. Fish fed diets with organic selenium (Selplex, Alltech®) had significantly higher selenium levels in the fillet with the adjusted mean of 0.0191 mg/100 g fillet compared to 0.0161 mg/100 g in fish fed inorganic selenium (Na-Selenite).