Impact of Dietary L‐Malic Acid Supplementation on Growth,Feed Utilization,Ash Deposition,and Hepatic Lipid Metabolism of Juvenile Genetically Improved Farmed Tilapia,Oreochromis niloticus

A 9‐wk feeding trial was conducted to investigate the effects of L‐malic acid (LMA) supplementation on growth, feed utilization, body composition, whole‐body mineral concentrations, and hepatic lipid metabolism of juvenile genetically improved farmed tilapia. LMA was included in the diets at 0, 0.8, or 3.2%. LMA‐supplemented treatments began to demonstrate weight gain improvement at 7 wk. After 9 wk, feed intake, weight gain, feed conversion ratio, and protein efficiency ratio were improved with either 0.8% or 3.2% LMA. Although whole‐body Fe, Mn, and Cu concentrations decreased, increased Ca and P concentrations contributed to improve whole‐body ash deposition with LMA inclusion. The concentrations of Na, K, Mg, and Zn and the Ca/P ratio of the whole body were not impacted by dietary treatments. Dietary LMA inclusion promoted whole‐body lipid deposition, which largely resulted from enhanced lipid accumulation in the liver and muscle tissues. In line with the increased liver lipid content, hepatic transcript levels of cytosolic malic enzyme 1 and acetyl‐CoA carboxylase a were upregulated, while mRNA levels of carnitine palmitoyltransferase 1A (CPT1A) and CPT1B were downregulated with LMA supplementation. However, increasing dietary LMA supply from 0.8 to 3.2% did not produce additional effects on most of the tested parameters, at least for a 9‐wk period. Taken together, it could be concluded that 0.8% LMA was superior to 3.2% LMA in tilapia feed and its inclusion could improve growth and feed utilization and enhance ash deposition and hepatic lipid accumulation.