Longitudinal metabolomic profiling across three age points reveals key metabolites associated with body weight, serum immunoglobulins, and biochemical parameters in pigeons

Post-hatch development in pigeons involves dramatic shifts in nutrition and metabolism. However, the underlying systemic metabolic reprogramming remains poorly characterized. Thus, longitudinal analyses of body weight (BW), serum immunoglobulins, biochemical parameters, and untargeted metabolomics at three key developmental stages: postnatal day 5 (PND 5, crop milk dependence; N = 10), PND 15 (transition to grains; N = 10), and PND 25 (independent grain intake; N = 10) were conducted. The BW increased significantly between PND 5 and PND 15 (P < 0.05), concomitant with elevated serum glucose, albumin, total cholesterol, and high-density lipoprotein. Immunoglobulin (Ig) dynamics revealed a significant decline in IgA at PND 15 and PND 25 relative to PND 5 (P < 0.05). The IgG showed a temporary significant decrease at PND 15 compared to PND 5 (P < 0.05), returning to PND 5 levels by PND 25. Metabolomics demonstrated dynamic pathway alterations. Comparing PND 15 to PND 5, differential metabolites were significantly enriched in five pathways (P < 0.05), most prominently alanine, aspartate and glutamate metabolism (P < 0.001) and purine metabolism (P = 0.003). The PND 15 to PND 25 transition featured prominent shifts, notably in glycerophospholipid metabolism (P < 0.001) and tricarboxylic acid (TCA) cycle continuation (P = 0.026). Crucially, PND 25 vs PND 5 analysis identified seven remodeled pathways, with core reprogramming involving alanine, aspartate and glutamate metabolism (P < 0.001), arginine biosynthesis (P < 0.001), and the TCA cycle (P = 0.002), which emerged as a central metabolic hub. The K-means clustering of 25 hub metabolites and physiological parameters delineated seven co-regulation patterns. Notably, BW and nutritional markers (albumin, cholesterol) correlated positively with TCA intermediates (citrate, α-ketoglutarate, malate; P < 0.05), while showing inverse associations with purine catabolites (e.g., guanine, xanthosine) and bile acids. Conversely, immunoglobulins correlated positively with purine metabolites and bile acids. This study identifies TCA cycle intermediates and purine metabolites as dual biomarkers regulating growth and immune function during pigeon development. These findings provide a foundation for targeted nutritional strategies that require adjustments as a function of aging, such as key metabolite supplementation and phospholipid modulation, to optimize pigeon management practices.