Changes in plasma UCP-1, leptin, lipids, and pro-inflammatory interleukins in calves from birth to weaning

The neonatal period is crucial for calf development, particularly for immune acquisition through colostrum intake, this study aimed to assess the energy metabolism and inflammatory response. Ten Italian Simmental calves were monitored from birth to 60 days of age, with blood samples taken at birth (0 d) to weaning. Plasma concentrations of UCP-1, leptin, TNF-α, IL-1β, IL-6, lipids, triglycerides, and total cholesterol were measured. Results showed significant dynamic changes (P < 0.05) in all parameters and showing an increasing trend from birth to the 60 d of age in investigated calves. The plasma leptin levels were positively correlated with the concentration of UCP-1 (r = 0.37, P = 0.0003), total lipids (r = 0.47, P < 0.0001), triglycerides (r = 0.53, P < 0.0001), total cholesterol (r = 0.38, P = 0.0002), and negatively correlated with TNF-α (r = −0.24, P 0.02). UCP-1 was positively correlated with the levels of total lipids (r = 0.31, P = 0.003), triglycerides (r = 0.29, P = 0.005), and IL-1β (r = 0.29, P = 0.005) in calves throughout the monitoring period. IL-6 values positively correlated with total lipids (r = 0.36; P = 0.0004), triglycerides (r = 0.37; P = 0.0003), and total cholesterol (r = 0.21; P = 0.04) in calves throughout the monitoring period. These findings suggest that lipid metabolism and inflammatory responses undergo significant changes as calves adapt to the neonatal phase and transition to solid food, with nutritional shifts playing a key role in metabolic and immune system development.