Effects of Thyroid Powder on Tadpole (<i>Lithobates catesbeiana</i>) Metamorphosis and Growth: The Role of Lipid Metabolism and Gut Microbiota

Abstract

A low metamorphosis rate of amphibian larvae, commonly known as tadpoles, limits the farming production of bullfrogs (Lithobates catesbeiana). This study aimed to examine the effects of processed thyroid powder as a feed additive on tadpole metamorphosis, lipid metabolism, and gut microbiota. Five groups of tadpoles were fed with diets containing 0 g/kg (TH0), 1.5 g/kg (TH1.5), 3 g/kg (TH3), 4.5 g/kg (TH4.5), and 6 g/kg (TH6) thyroid powder for 70 days. The results showed that TH increased the average weight of tadpoles during metamorphosis, with the TH6 group having the highest values. The TH4.5 group had the highest metamorphosis rate (p pparα, accb, fas, fadd6, acadl, and lcat genes, which are related to lipid metabolism (p Akkermansia (classified as Verrucomicrobia) was the corresponding genus, which is related to lipid metabolism. Specifically, the metabolic pathways of the gut microbiota were mainly enriched in metabolic-related functions (such as lipid metabolism), and there were significant differences in metabolic and immune pathways between the TH4.5 and TH0 groups (p Akkermansia), thereby promoting the growth of tadpoles. Consequently, a supplementation of 4.5 g/kg or 6 g/kg of TH is recommended for promoting the metamorphosis and growth of tadpoles.

Keywords

• lipid metabolism
• gut microbiota
• bullfrog
• amphibians
• metamorphosis