Brown adipose tissue in ruminants: development, thermogenic function, and nutritional regulation.

Brown adipose tissue (BAT) is essential for neonatal ruminants to maintain body temperature and survive postnatal cold stress through non-shivering thermogenesis. At birth, BAT is abundant and mainly distributed in the neck, shoulder, perirenal region, and around the heart, but declines with age ("whitening"). This review summarizes BAT developmental dynamics, physiological functions, and the nutritional regulation of BAT, focusing on how fatty acids, carnitine, vitamins, and minerals modulate thermogenic activity through effects on mitochondrial function, lipid metabolism, and key signaling pathways (e.g., UCP1, PGC-1α, and PPARγ). Evidence indicates that targeted nutritional strategies can enhance BAT function, improving neonatal cold tolerance, survival, and early growth performance. Finally, we highlight the use of multi-omics technologies as a promising future direction to decipher BAT regulatory networks and guide precise nutritional interventions.