The Effects of Creatine Monohydrate and Conjugated Linoleic Acid on Growth Performance and Fiber Type, Fiber-related Genes and Metabolic Enzymes in the Tilapia Muscle

We analyzed the effects of creatine monohydrate (CMH) and conjugated linoleic acid (CLA) on muscle fiber type, related genes, metabolic enzymes, and growth performance in tilapia (Oreochromis mossambicus). The addition of CMH and CLA in the basal feed significantly reduced the daily intake of tilapia, indicating that CMH and CLA had positive effects on improving the tilapia feed conversion rate. CMH upregulated the relative mRNA expressions of MyHC I, IIa/IIb in the tilapia muscle. The activities of oxidases (SDH, MDH), AMPK, and the mRNA expression levels of PGC-1 alpha, MEF2C, and GLUT4 were increased but those of MyHC IIx and LDH activity were decreased. CLA increased the proportion of oxidative muscle fibers in tilapia muscle while enhancing the activities of MDH, SDH, and AMPK and increasing mRNA expressions of PGC-1 alpha and GLUT4. However, it decreased the proportion of glycolytic muscle fiber types and LDH activity. CMH and CLA could activate the AMPK activity in the muscle, further up-regulating the gene expression in the AMPK pathway, enhancing oxidative metabolic ability, and transforming the muscle fiber type. The study provides a strategy for improving the quality of future tilapia culture by regulating muscle fiber type transformation through CMH and CLA supplementation.