PS4-21. Serum Metabolomic Changes Induced by Guanidinoacetic Acid Supplementation in Growing Nellore Cattle.

Abstract

Guanidinoacetic acid (GAA) is a fundamental precursor of creatine, and its role in muscle energy metabolism is of potential importance in growing cattle. The objective was to evaluate blood metabolic changes induced by GAA supplementation in Nellore cattle during the growing phase. The experimental lasted 280 days and during this phase, 51 recently weaned Nellore cattle (initial body weight [BW] of 265 ± 19 kg and age of 8 ± 2 months) were used. Animals were blocked by BW and randomly allocated to paddocks and assigned to four treatments: a control treatment without GAA supplementation (CON), and treatments supplemented with 3, 6, and 9 g·kg-1 of dry matter (DM) of GAA (GAA3, GAA6, and GAA9, respectively). Throughout the experimental period, animals received a protein-energy supplement at 3 g·kg-1 of BW daily, with or without GAA inclusion. At the end of the growing phase, blood samples were collected, centrifuged, filtered (3 kDa; 10,000 g, 30 minutes, 4 °C) to obtain serum for metabolomic analysis by nuclear magnetic resonance (¹H-NMR). Univariate statistical analyses were performed independently for each metabolite using linear models to evaluate treatment effects in an exploratory approach. The following pairwise comparisons were performed: CON × GAA3, CON × GAA6, and CON × GAA9. The ¹H-NMR analysis identified 48 metabolites common to all experimental groups during the growing phase. Supplementation with GAA3 resulted in greater concentrations of phosphocreatine (P = 0.042), glutamate (P = 0.001), glycine (P = 0.024), proline (P = 0.025), and uridine (P = 0.042) compared with the control group. In addition, dimethyl sulfone (P = 0.073), lysine (P = 0.081), succinate (P = 0.074), taurine (P = 0.069), and tyrosine (P = 0.088) showed increasing trends in the GAA3 group. Phosphocreatine remained elevated in the GAA6 group compared with the control (P = 0.046). Increases were also observed for glutamate (P = 0.013), proline (P = 0.001), and succinate (P = 0.006). Creatine showed a tendency toward higher concentration in the control group (P = 0.051), whereas isoleucine showed a tendency to increase in the supplemented group (P = 0.077). Animals receiving GAA9 presented greater concentrations of asparagine (P = 0.045) and glutamate (P = 0.040) compared with the control group. Conversely, glycerol concentration was lower in the GAA-supplemented groups (P = 0.039). Dimethyl sulfone (P = 0.055) and uridine (P = 0.053) showed increasing trends in GAA9, while ornithine tended to be greater in the control group (P = 0.092). Based on the results of this study, guanidinoacetic acid supplementation in growing Nellore bulls modulated energy and protein metabolism, as evidenced by changes in metabolite abundance compared to the control group.