Mitochondrial and peroxisomal fatty acid oxidation capacities increase in the skeletal muscles of young pigs during early postnatal development but are not affected by cold stress.

In pigs, the optimal utilization of energy substrates within muscle fibers is a prerequisite of the utmost importance for successful adaptation to extra-uterine life. In the present work we demonstrate that fatty acid (FA) oxidative capacities increased within the first five days of life in piglet skeletal muscle. Mitochondrial FA oxidation capacities increased more in the rhomboideus oxidative than in the longissimus lumborum glycolytic muscle (+114% vs. +62%, P < 0.001). The apparent rate of fatty acid degradation by peroxisomes represents 30 to 40% of total FA oxidation capacities and increased by about 170% (P < 0.001) with age in both muscles. The postnatal enhancement of skeletal muscle oxidative capacities was further supported by a rise in acid-soluble and long-chain acylcamitine tissue levels (+67%, P < 0.01), and plasma levels of albumin (+160%, P < 0.001). Cold stress had no effect on mitochondrial and peroxisomal FA oxidation but greatly enhanced (+61%, P < 0.05) the circulating levels of non-esterified fatty acids at five days of life.