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

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 (<i>p</i> < 0.05); activated hepatic lipid metabolism, as manifested by enhanced LPL and HL activity; upregulated lipid metabolism-related gene expression (<i>fasn</i>, <i>acc</i>, <i>acadl</i> and <i>cpt1α</i>) (<i>p</i> < 0.05); and distinctly elevated the activity of SOD, CAT and GPX (<i>p</i> < 0.05), suggesting improved antioxidant capabilities (<i>p</i> < 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.