Aquaculture Reports (Jul 2021)
The effect of royal jelly dietary on growth performance and expression of genes related to growth and immunity of zebrafish, Danio rerio
Abstract
Royal jelly (RJ) is a natural product that is fed to bee queens during their entire life, and it contributes to their growth and development, fertility, and long lifespan. Although it is known that these unique effects of RJ, it has not been evaluated fed diet studies in fish until now. The study was carried out to determine the influence of RJ diets with different rates (0.0; 0.1; 0.4; 1.6 and 6.4 %) on expressions of growth (GH-I, IGF-I) and immune system (TGF-β) hormones of zebrafish (Danio rerio). Growth parameters was also studied and found to be higher in D4 group containing 1.6 % additives compared with other groups. RJ dietary supplementation showed significantly up-regulated in GH-1 gene expression in the liver tissues of fish fed D5 diet respect to the control group. Conversely, expression level was down-regulated in kidney tissues of group D4 compared with the control group (p < 0.05). IGF-1 gene expression noticeably increased in the muscle tissues of fish fed the D5 diet containing 6.4 % RJ compared to the control group. The greatest decrease was found in the muscle tissues of group D3 diet (p < 0.05). Although among the diet groups the highest amount of TGF-β expression was found in the muscle tissue of fish that were fed the D4 diet. It was seen that the mRNA level amounts obtained in all applications were below the level of the control group. These results indicate that the high-dose RJ included in the feed positively influenced the growth hormones of the zebrafish at transcriptomic level. To sum up, this study highlights the importance that 1.6 % or 6.4 % RJ included in the diet of zebrafish positively influenced their growth performance and growth hormone gene expression and may be considered a potential to be sustainable alternative for growth promoter in aquaculture practice.
