Abstract
A 56-day culture experiment followed by an acute low salinity challenge was conducted to evaluate the effects of Rhodobacter sphaeroides protein (RSP) substitution of fishmeal and Coenzyme Q10 (CoQ10) supplementation on growth performance, intestinal microbiota and compressive capacity of Litopenaeus vannamei (L. vannamei). Four experimental diets were formulated: FM diet (20% fishmeal), RSP diet (20% RSP instead of 20% fishmeal), CoQ10 diet (20% fishmeal supplemented with CoQ10 at 0.08 g kg–1), RSP + CoQ10 diet (20% RSP supplemented with CoQ10 at 0.08 g kg–1). The obtained results were denoted that L. vannamei fed CoQ10 diet could improve growth performance (weigh gain and specific growth rate), condition factor and crude lipid, and decrease hepatosomatic index, but no differences were found in survival rates. High throughput sequencing on intestinal microbiota indicated that intestinal microbiota of L. vannamei consisted mainly of Proteobacteria and Firmicutes. The species richness of the RSP diet was remarkably higher than that of the other diets. Moreover, the presence of RSP and CoQ10 may improve intestinal homeostasis by inhibiting the propagation of Vibrio. Compared to FM diet and RSP diet, supplementation of CoQ10 significantly improved the compressive capacity of L. vannamei against the acute low salinity challenge, as indicated by higher survival rates as well as higher activities of T-AOC and higher transcript levels of SOD, HSP70, and Relish gene. Our findings demonstrated that RSP could serve as a novel FM and CoQ10 could serve as a prospective feed additive to help L. vannamei to overcome environmental stresses.
Highlights
As a highly efficient osmoregulator, the salinity of L. vannamei’ live was wide-ranging, from 0.5 to 50 ppt (Xu et al, 2018)
For the evaluation of the impacts of RSP (All the main raw materials were fermented, inactivated and dried to gain the Rhodobacter sphaeroides protein product; Zhejiang NHU Company Ltd., Xinchang, Zhejiang) and Coenzyme Q10 (CoQ10) (Zhejiang NHU Company Ltd., Xinchang, Zhejiang) on L. vannamei, four experimental diets were designed as follows: FM diet contains 20% fishmeal; RSP diet contains 20% RSP instead of 20% fishmeal; CoQ10 diet contains 20% fishmeal supplemented with CoQ10 at 0.08 g kg−1; RSP + CoQ10 diet contains 20% RSP supplemented with CoQ10 at 0.08 g kg−1 (Table 1)
A higher specific growth rate (SGR) was found in shrimp fed with CoQ10 diet than that in shrimp fed those diets and no significant differences were found among other diets (P > 0.05; Figure 1D)
Summary
As a highly efficient osmoregulator, the salinity of L. vannamei’ live was wide-ranging, from 0.5 to 50 ppt (Xu et al, 2018). 5 and 54 ppt salinities increase the susceptibility of L. vannamei to White Spot Syndrome Virus (WSSV) (Ramos-Carreno et al, 2014). L. vannamei juveniles exhibited an impaired resistance to pathogens due to long-term low salinity (2.5–5 ppt) (Lin et al, 2012). The growth performance of juvenile L. vannamei would be significantly suppressed when exposure to salinity 3 ppt (Huang et al, 2019). All these data indicate that the tolerance to stress, the resistance to pathogens and the poor survival rates have become restrictive factors for inland low salinity L. vannamei farming (Li et al, 2008). In the long-term feeding experiment, there is a need to further explore some new fishmeal substitutions and dietary supplementations to enhance nutrient uptake and increase host defense against acute salinity challenge
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