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Sago starch is a locally grown and produced starch resource in Malaysia. In this study, corn starch to sago starch ratios (CS:SS) of 0:20, 5:15, 10:10, 15:5 and 20:0 were included in feed mixture to contain 20% starch and produce five isonitrogenous and isocaloric (30% crude protein and 16.7 kJ/g, respectively) tilapia Oreochromis sp. diets. Diets were preconditioned to contain 40% moisture and extruded using a single-screw extruder at screw speed of 120 rpm using three different temperature profiles (I 60-100-140-180˚C; II 60-100-120-160˚C; and III 60-120-120-180˚C). Effects of these factors were evaluated on physical properties of extrudates including expansion ratio, bulk density, water stability, floatability, sinking velocity and durability. From the results, different temperature profiles and CS:SS had significant effects (p<0.05) on expansion ratio and floatability. Sago starch performed as a good binder as it gave higher percentage of water stability and pellet durability. The mixture with 10:10 of corn to sago starch extruded using temperature profile II (60-100-120-160˚C) produced the best extrudates with desirable physical properties.

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Recently, the rising demand for high-quality seafood has created a fresh look at the sustained and adequate aquafeed as a necessity. Considering the potential of microalgae cells, many companies are looking for practical methods to enhance the nutritional content of these microorganisms as valuable aquafeed. In this attempt, Thalassiosira weissflogii isolated from the Caspian Sea and identified with morphology and molecular characteristics. In order to improve lipid content, this strain was cultivated in normal and nitrogen deficiency F/2 medium for 18 and 30 days. The growth indices, total lipid, fatty acids profiles were measured in both cases.
Growth of T. weissflogii during nitrogen deficiency conditions was associated with a sharp decline in cell growth and significant rise in lipid production such as polyunsaturated fatty acids (PUFAs). Although the eicosapentaenoic acid (EPA) level was reduced by half under nitrogen deficiency condition (8.8 to 3.23 % TFA), the amount of docosahexaenoic acid (DHA) escalated during this situation (3.5 to 12.63 % TFA). Results showed that the concept of N-deficiency conditions along with prolonged culturing could improve PUFA n-3 content to provide highly valuable feed for shellfish and shrimp industries.