Abstract
Simple SummaryWe evaluated Nannochloropsis spp. as a feed additive for the Pacific white shrimp by testing for thermal shock resistance, immunology, and midgut microbiology. Nannochlorpsis spp. are rich in Eicosapentaenoic acid, an n-3 fatty acid. This study demonstrated that the inclusion of these microalgae in the diet increased shrimp resistance to thermal shock and stimulated shrimp immune defense.This work aimed to evaluate Nannochloropsis spp. as feed additive in the diet of Pacific white shrimp for their effect on midgut microbiology, thermal shock resistance and immunological parameters. Initially, the digestibility of the microalgae meal was assessed, and the apparent digestibility coefficient (ADC) was determined. The ADC was, in general, high in lipids (78.88%) and eicosapentaenoic fatty acid (73.86%). Then, Nannochloropsis spp. were included in diets at four levels (0, 0.5, 1 and 2% inclusion). The shrimp were reared in 500 L clear water tanks containing 20 shrimp per tank with an initial weight of 6.05 ± 0.06 g and fed four times a day. Shrimp fed with supplemented diets containing Nannochloropsis spp. (0.5 and 2%) presented higher resistance to thermal shock when compared to the non-supplemented group (control). Shrimp fed with 1 and 2% of algae inclusion had a higher production of reactive oxygen species (ROS) when compared to other treatments. No statistical difference was observed in the immunological parameters and microbiology of the intestinal tract. Thus, the inclusion of Nannochloropsis spp. in shrimp diets at 0.5 and 2% levels increases resistance to thermal shock and ROS production in shrimp.
Highlights
The ACD from longchain polyunsaturated fatty acids was 100%, and the fatty acids belonging to the n-3 group reached 95%
It was possible to observe the complete digestibility of some fatty acids such as docosapentaenoic, arachidonic, linolenic, linoleic and oleic, as well as protein
The digestibility of Nannochloropsis spp. as seen in Litopenaeus vannamei was high for all nutrients
Summary
The harmful potential effect of synthetic drugs on animals and the environment made these compounds problematic. To avoid their use, alternative methods have been studied, for instance, good handling practices of production and the enhancement of the immunological resistance of shrimps. The development of the immunocompetence of shrimps strengthens their immune system. This can be developed throughout the use of natural substances in diets, namely immunostimulants, such as some plant additives and seaweeds [2,3,4,5,6]
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