Maslinic acid, a natural triterpene, and ration size increased growth and protein turnover of white muscle in gilthead sea bream (Sparus aurata)

Maslinic acid (MA) is a pentacyclic triterpene used, at experimental level, as an additive to stimulate growth, protein-turnover rates and hyperplasia in fish. In this experiment we have studied the effects of feeding with MA at daily fixed ration of 10 g kg-1 of body mass, on growth, protein-turnover rates and nucleic acid concentration in white muscle of gilthead sea bream grown in a local fish farm. The experimental groups contained 0 (control), 50 (MA50) and 100 (MA100) mg MA per kg of diet. Two groups were provided feed ad libitum (control AL and MA100AL), while three were given a fixed ration (control R, MA50R, and MA100R). We have determined the following: growth rate; nucleic acid and protein levels; relative and absolute protein-accumulation (KG, AG), synthesis (KS, AS) and degradation (KD, AD) rate, protein-synthesis capacity (CS), protein-synthesis efficiency (KRNA), protein-synthesis rate per DNA (KDNA) and protein-retention efficiency. At the end of the experiment, higher body weights and muscle growth rates were found in both groups of fish fed with 100 mg MA per kg of diet. Feed-efficiency rate, protein-efficiency ratio and protein productive value, were higher in the MA100AL group than in control AL. Fractional and absolute protein-synthesis and degradation rates in white muscle of MA100AL and MA100R fish were higher than in the control, resulting in a higher protein-accumulation rate and tissue growth. Total DNA content, indicated cell hyperplasia, was higher in MA100AL and MA100R than its respective controls. Studies of optical and electronic microscopy corroborated these results. These findings indicate that MA added to the diet can stimulate the growth, white-muscle protein-turnover rates and tissue hyperplasia in gilthead sea bream.