Dietary Effects of Selenium Nanoparticles on Growth Performance, Survival Rate, Chemical Composition, and Muscle Bioaccumulation of Nile Tilapia (Oreochromis niloticus)

This study evaluated the effect of selenium nanoparticles on growth performance, survival rate, chemical composition, and bioaccumulation of selenium in the muscle of Nile tilapia (Oreochromis niloticus). Fish with an average weight of 33.1 ± 1.0 g were distributed in 12 fiberglass tanks and fed for 56 days with different levels of selenium nanoparticles, 0, 0.5, 1, and 2 mg/kg of diet, considered as control, T1, T2, and T3, respectively. Body weight increase (BWI), specific growth rate (SGR), and food conversion ratio (FCR) were significantly influenced by 2 mg/kg of selenium nanoparticles compared to the other treatments, in particular control and T1 with 0.5 mg/kg selenium (P < 0.05). The survival rate was also significantly affected in T2, especially compared to the control (P < 0.05). In addition, protein, ash, and moisture percentages of muscle showed statistically different levels in fish fed a diet containing 2 mg/kg of selenium nanoparticles compared to the control treatment (P < 0.05). The results of the selenium bioaccumulation in the muscle of trial diets showed a significant difference in selenium nanoparticle bioaccumulation among treatments, with the highest revealed in the 2 mg/kg nanoparticle group (P < 0.05). Overall, selenium nanoparticles significantly improved the growth performance, survival, and chemical composition (protein in particular) of Nile tilapia, especially in the T2 and T3 treatments.

Characterization of fish sausage manufactured with combination of sunflower oil and fish oil stabilized with fish roe protein hydrolysates

The present study aimed to determine the effect of adding protein hydrolysates obtained after 30, 60, and 90 min enzymatic hydrolysis of fish roe on properties of silver carp sausages enriched with fish oil during storage at 4 °C for 30 days. Properties of the fortified sausages were determined by assessment of primary and secondary oxidation, fatty acid composition, microbial spoilage, texture, and organoleptic properties. The results indicated that the hydrolysates could retard oil oxidation and microbial spoilage and preserve n - 3 fatty acids in fish sausages during the refrigerated storage. Also, they rendered firmer microstructure with smaller oil droplets to the sausages. Fish sausages fortified with the hydrolysates were lighter and exhibited better textural and sensory properties. It can be concluded that enzymatic hydrolysates from discarded fish roe can be added to fish sausages containing fish oil to retard oil oxidation and microbial spoilage and improve sausage properties.