# Dietary Guanidinoacetic Acid Supplementation Improves Growth Performance of Plateau Yaks Through Plasma Metabolome Modulation

## TL;DR

Adding guanidinoacetic acid to yak diets improves growth, possibly by changing amino acid metabolism.

## Contribution

The study reveals how GAA supplementation affects yak growth through plasma metabolome modulation.

## Key findings

- Higher GAA levels improved average daily gain in yaks.
- Metabolites like serotonin and N(omega)-Hydroxyarginine were affected by GAA supplementation.
- Arginine and tryptophan metabolism pathways were significantly altered.

## Abstract

This study evaluated the effects of dietary guanidinoacetic acid (GAA) supplementation on growth and metabolism in yaks by randomly assigning twenty-four male animals to a control group (basal diet) and two treatment groups (0.055% or 0.11% GAA) for a 90-day feeding trial. The results showed a positive trend in growth performance, with the higher GAA supplementation level leading to a more noticeable improvement in average daily gain. Serum biochemical indices were generally unaffected, though a tendency of reduced glutathione peroxidase activity was observed. Non-targeted metabolomics in plasma identified multiple differentially abundant metabolites across groups. Enrichment analysis highlighted significant alterations in metabolic pathways related to tryptophan, glycerophospholipid, and arginine metabolism. Notably, metabolites such as N(omega)-Hydroxyarginine, 5-hydroxytryptophan, and serotonin were specifically affected. In conclusion, dietary GAA supplementation, particularly at 0.11%, has the potential to enhance growth in yaks, which may be attributed to its role in modulating amino acid metabolism, especially arginine and tryptophan pathways. These findings provide a metabolic perspective for the application of GAA as a feed additive in yak production.

This study aimed to investigate the effects of dietary guanidinoacetic acid (GAA) supplementation on yak physiology by evaluating growth performance, serum biochemical indices and plasm metabolomic profiles to elucidate the underlying regulatory mechanisms. Twenty-four male yaks (4–5 years; 249.38 ± 11.69 kg BW) were randomly allocated to three dietary treatments (n = 8): CON (basal diet), GAA1 (basal diet + 0.055% GAA), and GAA2 (basal diet + 0.11% GAA), with 55:45 of concentrate:roughage (DM basis). After a 10-day adaptation period, the feeding trial lasted 90 days. Body weights were measured on days 0 and 90 for growth performance evaluation, with blood samples collected on the final day for separation into serum and plasma to assess serum metabolic and antioxidant parameters and for plasma metabolomic profiling. The result showed that growth performance parameters displayed a positive trend, with average daily gain (ADG) showing marginal improvement (p = 0.072). Serum biochemical analysis revealed that dietary supplementation of GAA had no effect on serum biochemical parameters while tendency decreased GSH-Px activity (p = 0.087). Non-targeted metabolomics identified 39–121 differentially abundant metabolites in plasma across treatment groups. Kyoto encyclopedia of genes and genomes (KEGG) enrichment analysis of these metabolites revealed pathways such as tryptophan metabolism, glycerophospholipid metabolism, and arginine metabolism. Among the differentially abundant metabolites, N(omega)-Hydroxyarginine and tryptophan metabolites such as 5-hydroxytryptophan and serotonin were specifically highlighted. In conclusion, dietary supplementation of GAA in yaks has been confirmed to improve ADG, with a 0.11% supplementation level being more effective, and this may be associated with GAA enhancing amino acid metabolism, particularly arginine and tryptophan metabolism.