Enhancement of growth performance, muscle nutrient composition, and nutritional value in rainbow trout (<i>Oncorhynchus mykiss</i>) by guanidinoacetic acid-enriched diets.
Dietary supplementation with 600 mg/kg GAA significantly improves growth performance and muscle quality in rainbow trout, as evidenced by increased body weight and enhanced nutrient composition.
Where it sits
this study against the rest of the mgf (mechano growth factor) corpusSummary and findings
The study measured the effects of dietary guanidinoacetic acid (GAA) supplementation on growth performance and muscle quality in juvenile rainbow trout. A total of 450 fish were assigned to five groups receiving different GAA concentrations, with significant findings at 600 mg/kg. The G6 group showed increased body weight, protein efficiency ratio, and improved muscle nutrient composition compared to the control group.
Abstract
The role of guanidinoacetic acid (GAA) in modulating nutritional value and muscle quality warrants attention, particularly given the scarcity of mechanistic studies in aquatic animals. A total of 450 healthy juvenile rainbow trout (<i>Oncorhynchus mykiss</i>, aged approximately 76 d post-hatch, initial body weight 7.77 ± 0.14 g) were randomly distributed into 5 groups (3 replicates per group, 30 fish per replicate) to investigate the effects of dietary GAA supplementation at concentrations of 0, 300, 600, 1200, and 2400 mg/kg on muscle nutritional value and quality, designated as groups G0, G3, G6, G12, and G24, respectively. After an 8-week feeding trial, dietary supplementation with 600 mg/kg GAA significantly increased final body weight and protein efficiency ratio, and decreased feed conversion ratio compared to the G0 group (<i>P</i> < 0.05). Whole-body crude protein and crude lipid contents were significantly affected by dietary GAA supplementation, with the G6 group exhibiting significantly higher levels of total amino acids, non-essential amino acids, and essential amino acids than the G0 group (<i>P</i> < 0.05). In parallel, GAA supplementation significantly enhanced muscle polyunsaturated fatty acid deposition (<i>P</i> < 0.05), with linear increases observed for polyunsaturated fatty acid and linoleic acid (<i>P</i> < 0.05), and a quadratic response for docosahexaenoic acid (<i>P</i> = 0.003). Notably, the G6 group exhibited the highest combined docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA) content (<i>P</i> = 0.011). Nutritional evaluation based on FAO/WHO standards confirmed that dietary GAA supplementation significantly improved essential amino acid index (EAAI; <i>P</i> < 0.001), with the highest value observed in the G6 group (72.806). Met + Cys was the first limiting amino acid across all GAA treatments. Moreover, GAA supplementation significantly upregulated the expression of genes involved in lipid metabolism, including <i>gpat</i>, <i>srebp 1</i>, <i>fas</i>, and <i>lpl</i>, as well as mechanistic target of rapamycin (mTOR) signaling-related genes, including <i>tgf-β</i>, <i>tor</i>, <i>igf-1</i>, and <i>4e-bp1</i>, with the G6 group showing significantly higher expression levels than the G0 group (<i>P</i> < 0.05). Antioxidant analysis further revealed significantly lower malondialdehyde levels in the G6 group (<i>P</i> < 0.001). Collectively, these findings demonstrate that dietary supplementation with 600 mg/kg GAA effectively enhances growth performance, whole-body chemical composition, and muscle nutritional value in rainbow trout, likely through the coordinated regulation of amino acid utilization, lipid metabolism, and antioxidant defense systems.
Background
The study addresses the role of guanidinoacetic acid (GAA) in enhancing nutritional value and muscle quality in aquatic animals, an area with limited mechanistic research. Prior studies have suggested potential benefits of GAA in various species, but specific effects on muscle quality in fish remain underexplored. Understanding these effects is important for optimizing aquaculture practices and improving fish health.
Methods
A total of 450 juvenile rainbow trout (Oncorhynchus mykiss), aged approximately 76 days post-hatch with an initial body weight of 7.77 ± 0.14 g, were randomly assigned to five groups receiving different concentrations of GAA (0, 300, 600, 1200, and 2400 mg/kg) over an 8-week feeding trial. Each group consisted of three replicates with 30 fish each. Primary outcomes included final body weight, protein efficiency ratio, and whole-body composition.
Results
The primary endpoint showed that the G6 group had a significantly increased final body weight compared to the G0 group, P < 0.05. Additionally, the G6 group exhibited a significantly improved protein efficiency ratio and higher levels of total amino acids compared to G0, P < 0.05. The EAAI was significantly higher in the G6 group at 72.806, P < 0.001.
Interpretation
The findings suggest that GAA supplementation at 600 mg/kg can enhance growth performance and muscle quality in juvenile rainbow trout, aligning with previous literature on amino acid supplementation. However, the clinical significance of these findings may be limited by the small sample size and the specific focus on juvenile fish, which may not translate to other life stages or species. The study's results imply potential benefits for aquaculture but warrant further investigation to confirm applicability.
Key findings
- Final body weight significantly increased in the G6 group compared to G0, P < 0.05.
- Protein efficiency ratio significantly improved in the G6 group compared to G0, P < 0.05.
- Whole-body crude protein and lipid contents were significantly higher in the G6 group than in G0, P < 0.05.
- EAAI was significantly improved in the G6 group with a value of 72.806, P < 0.001.
- Docosahexaenoic acid (DHA) + eicosapentaenoic acid (EPA) content was highest in the G6 group, P = 0.011.
- Malondialdehyde levels were significantly lower in the G6 group, P < 0.001.
Limitations
- small sample size of 450 fish
- focused solely on juvenile rainbow trout
- short 8-week follow-up period
- no long-term effects assessed
- single-site study