# Synergistic taurine and methionine supplementation enhances growth and cholesterol regulation in Totoaba macdonaldi

## TL;DR

Adding taurine and methionine together improves the growth and cholesterol levels of Totoaba fish more effectively than using either supplement alone.

## Contribution

The study shows that combining low doses of taurine and methionine enhances growth and cholesterol regulation in Totoaba macdonaldi.

## Key findings

- Combined taurine and methionine supplementation significantly increased growth rates compared to individual supplements.
- Taurine supplementation reduced total cholesterol levels in Totoaba fish.
- Methionine alone increased liver cholesterol levels, while taurine increased total taurine content in fish tissues.

## Abstract

Totoaba (Totoaba macdonaldi) aquaculture offers economic and ecological advantages. However, its culture still relies on fishmeal in diets because alternative protein sources show reduced productive performance. The current study assessed the impact of low concentrations of methionine and taurine together with alternative proteins, on the productive performance of T. macdonaldi over a 60-day experimental period. Four diets were formulated for this purpose, a basal diet (D-BD), the basal diet with methionine (D-MET), the basal diet with taurine (D-TAU), and the basal diet with methionine and taurine (D-MET + TAU). The present experiment used a randomized design. One hundred forty-four juveniles (41.0 ± 0.5 g in weight) were randomly distributed in 12 tanks (500 L) in triplicate groups to assess biological indices, cholesterol content, hepatic gene expression, and the synthesis and transport of taurine. The statistical analysis revealed that the dietary treatments D-MET and D-TAU positively affected the growth rate, whereas their interaction resulted in a significantly higher growth (p < 0.05). The expression of the igf-1 gene in the liver increased and showed a positive interaction. When TAU and MET were limited, there was an observed overexpression of csad in hepatic tissue. Diets supplemented with TAU showed a decrease in total cholesterol level, whereas cholesterol level in the liver increased with MET supplemented alone. Total TAU content in fish tissues was significantly higher when both TAU and MET were supplemented. In conclusion, T. macdonaldi exhibits a limited capacity, for TAU synthesis, and MET limitation appears to restrict growth potential.