Metabolic and histologic responses of pacu (Piaractus mesopotamicus) fed diets supplemented with increasing concentrations of ractopamine

Abstract

An experiment was conducted during 60 days with forty pacu males fed diets supplemented with increasing concentrations of ractopamine (0.00, 11.25, 22.50, 33.75, and 45.00 mg kg −1). Eight fish were evaluated for each experimental diet. Performance and survival rate of the fish were measured. At the end of the experiment, blood was collected to determine the levels of cortisol, triacylglycerol, and protein. Moreover, the liver was collected to determine the activities of glucose-6phosphate dehydrogenase and malic enzymes. The fillets were collected to determine chemical composition, and histologic cuts were analyzed to verify muscle growth and deposition of adipose tissue between muscle fibers. Increasing concentrations of dietary ractopamine did not change feed intake, fillet yield, fillet content of protein and ash, and frequency of relative distribution of muscle fibers. By increasing the dietary ractopamine concentration, the serum cortisol level was elevated. Ractopamine supplementation (45.00 mg kg −1) increased serum levels of triacylglycerol and protein and reduced the activity of hepatic lipogenic enzymes and the survival rate of the fish, probably in response to the high concentration of circulating cortisol. In addition, the higher level of ractopamine supplementation evaluated in this research impaired the weight gain and feed conversion. However, 11.25 mg kg −1 ractopamine reduced the ether extract level determined in the fillet and the fat deposition between muscle fibers, improving the nutritional quality of meat.

Beta-Agonist, Ractopamine Hydrochloride, Improves Growth, Alters Body Composition, and Suppresses Gonadal Maturation in All-Female Giant Freshwater Prawn, Macrobrachium rosenbergii

“…7 Aquaculture Nutrition Dietary ractopamine supplementation was found to be beneficial in lowering body lipid and raising body protein in all-female prawns in our study, as it has been previously reported for blue catfish I. furcatus [30] and channel catfish I. punctatus [13] fed with the beta-adrenergic agonist compounds L644, 969, and ractopamine, respectively. Drumond et al [33] reported the reduction of lipid deposition between muscle fibers in pacu. Similarly, the addition of 8 mg/kg ractopamine to the feed altered the abdominal muscle chemical composition of Nile tilapia, where the treated fish had a 23.3% lower lipid content than the control fish [5].…”

Combined effect of dietary l ‐carnitine and ractopamine supplementation on growth and nutritional composition of Labeo calbasu (Hamilton, 1822)

“…A higher dose of ractopamine of 45 mg kg −1 increased the protein, and lower dose of 11.25 mg kg −1 ractopamine reduced the ether extract level in the fillets. The lipid deposition between muscle fibres of Pacu was also found to be reduced (Drumond et al, 2018). The supplementation of ractopamine and l-carnitine results in muscle protein accretion, nitrogen retention by increased synthesis and reduction in the degradation of protein but accelerates fatty acid oxidation (Ji et al, 1996;Salem et al, 2006).…”