Growth curves and age-related changes in carcass characteristics, organs, serum parameters, and intestinal transporter gene expression in domestic pigeon (Columba livia)

Two experiments were conducted to fit growth curves, and determine age-related changes in carcass characteristics, organs, serum biochemical parameters, and gene expression of intestinal nutrient transporters in domestic pigeon (Columba livia). In experiment 1, body weight (BW) of 30 pigeons was respectively determined at 1, 3, 7, 14, 21, 28, and 35 days old to fit growth curves and to describe the growth of pigeons. In experiment 2, eighty-four 1-day-old squabs were grouped by weight into 7 groups. On d 1, 3, 7, 14, 21, 28, and 35, twelve birds from each group were randomly selected for slaughter and post-slaughter analysis. The results showed that BW of pigeons increased rapidly from d 1 to d 28 (a 25.7-fold increase), and then had little change until d 35. The Logistic, Gompertz, and Von Bertalanffy functions can all be well fitted with the growth curve of domestic pigeons (R² > 0.90) and the Gompertz model showed the highest R² value among the models (R² = 0.9997). The equation of Gompertz model was Y = 507.72 × e-³.⁷⁶ᵉˣᵖ⁽⁻⁰.¹⁷ᵗ⁾ (Y = BW of pigeon (g); t = time (day)). In addition, breast meat yield (%) increased with age throughout the experiment, whereas the leg meat yield (%) reached to the peak on d 14. Serum total protein, albumin, globulin, and glucose concentration were increased with age, whereas serum uric acid concentration was decreased (P < 0.05). Furthermore, the gene expressions of nutrient transporters (y⁺ LAT2, LAT1, B0AT1, PepT1, and NHE2) in jejunum of pigeon were increased with age. The results of correlation analysis showed the gene expressions of B0AT1, PepT1, and NHE2 had positive correlations with BW (0.73 < correlation coefficient <0.80, P < 0.0001). It can be concluded that, 28-day-old should be the latest market age for meat type pigeon. And the various physiological and functional properties of organs, serum profiles, and gene expression of nutrient transporters in small intestine might cause the differences in their development patterns.