Influence of feeding on the generation of reactive oxygen species and zootechnical performance in larvae of shrimp Litopenaeus vannamei
Diatoms are widely used in the feeding of larvae of peneid shrimp, with the species Conticribra weissflogii and Chaetoceros muelleri being the most used, however, to date, studies on their influence on the antioxidant system of organisms in cultivation are still scarce. Thus, the objective of this work was to evaluate the effect of microalgae C. weissflogii and C. muelleri on the antioxidant responses and development of larvae of L. vannamei. In experiment 1, the microalgae C. weissflogii offered to the larvae in natura form was used in two treatments: (i) C. weissflogii (collected and offered on the 4th day of cultivation of the microalgae) and (ii) control (collected and offered on different days of cultivation). The treatment in which the microalgae was collected on the 4th day of cultivation (C .weissflogii) showed a higher concentration of total flavonoids and the animals fed with this treatment showed greater final survival and greater body size when compared to the control (p <0.05). For water quality parameters, total polyphenols, rate of metamorphosis, temperature stress test and generation of reactive oxygen species (ROS) in vivo, there were no significant differences. The second experiment consisted of two stages (A and B) with two treatments using the microalgae C. muelleri and C. weissflogii, collected on the 5th day of cultivation and offered as a paste. Stage A lasted from protozoan I to mysis I and stage B from mysis I to post-larvae 1. The content of total flavonoids and polyphenols was evaluated on the 3rd,5th and 7th day of cultivation and it was found that the 5th day had higher levels of polyphenols and the 7th day of flavonoids (p <0.05) in the two microalgae species. The treatment in which the microalgae C. muelleri was used showed greater final survival in step A, while in step B, the treatment using C. weissflogii showed greater final survival and body size of the larvae (p <0.05). For the ROS concentration, a significant reduction in the mysis II phase was observed in the C. muelleri treatment (p <0.05). In post-larva 1, both treatments showed a high increase in the ROS concentration when compared with the other larval phases (p <0.05). Both microalgae showed important advantages when offered on a specific day of cultivation, proposing,in future studies, consider offering a controlled mix of C. muelleri and C. weissflogii.