# Feasibility Evaluation of Dried Whole Egg Powder Application in Tadpole (Lithobates catesbeianus) Feed: Effects on Growth, Metamorphosis Rate, Lipid Metabolism and Intestinal Flora

## TL;DR

This study shows that adding dried whole egg powder to tadpole feed improves growth, metabolism, and gut health similarly to fishmeal.

## Contribution

The study demonstrates that dried whole egg powder can effectively replace fishmeal in tadpole diets without compromising performance.

## Key findings

- FM or DWEP inclusion significantly improved growth and metamorphosis rates in tadpoles.
- Both FM and DWEP enhanced hepatic lipid metabolism and antioxidant enzyme activity.
- FM or DWEP increased beneficial gut bacteria while reducing harmful ones.

## Abstract

This study investigated the feasibility of dried whole egg powder application in tadpole (Lithobates catesbeianus) feed, focusing on the effects on their growth, metamorphosis rate, lipid metabolism and intestinal flora. This study indicated that fishmeal (FM) or dried whole egg powder (DWEP) inclusion significantly enhanced the growth performance and metamorphosis rates of tadpoles. FM or DWEP inclusion activated hepatic lipid metabolism. Moreover, the hepatic antioxidant capacity was enhanced by FM or DWEP inclusion, as evidenced by increased SOD, CAT and GPX activity. The supplementation of FM or DWEP stimulates beneficial microbes like Actinobacteria, while suppressing harmful bacteria such as Proteobacteria. These results could provide valuable data for future tadpole feeds.

At present, studies on tadpole nutrition and metabolism are scarce. This study aimed at comparing the influence of two protein sources, fishmeal (FM) and dried whole egg powder (DWEP), on tadpoles from the perspective of growth, the metamorphosis rate, lipid metabolism, antioxidant properties and the intestinal flora. In this experiment, the control diet was set to contain no FM or DWEP. Based on the control diet, 5% and 10% FM or DWEP were included, respectively. The results of the experiment indicated that FM or DWEP inclusion significantly enhanced the growth performance and metamorphosis rate (p < 0.05); activated hepatic lipid metabolism, as manifested by enhanced LPL and HL activity; upregulated lipid metabolism-related gene expression (fasn, acc, acadl and cpt1α) (p < 0.05); and distinctly elevated the activity of SOD, CAT and GPX (p < 0.05), suggesting improved antioxidant capabilities (p < 0.05). Moreover, the inclusion of FM or DWEP elevated the relative abundance of Actinobacteria and Actinomyces and reduced the relative abundance of Proteobacteria. Unexpectedly, no significant differences were observed between the FM and DWEP groups regarding the above detected indices. This indicates that using DWEP to replace FM is a viable option.