Polka-dot grouper, Cromileptes altivelis, can utilize dietary fat efficiently

Abstract

Polka‐dot grouper, Cromileptes altivelis, a highly‐prized fish in Asian live fish markets, is a slow‐growing species. Long‐chain (LCF) or medium‐chain fatty acids (MCF) were fed to polka‐dot grouper (14 g initial weight) for 8 weeks to see if growth could be stimulated. Five dietary treatments were compared: a control diet with low fat (56 g kg−1) or diets that contained either moderate (150 g kg−1) or high (300 g kg−1) supplements of fat that were added either as olive oil for the LCF or coconut oil for the MCF. Control fish performed well; they grew at 2.2 g week−1, had a dry matter feed conversion ratio of 1.0 and deposited dietary protein and energy at efficiencies of 25 and 26%. Fish fed LCF at moderate levels performed better than controls but, when fed LCF at high levels or MCF at any level, their performance was inferior to controls. We conclude that dietary supplementation with 150 g kg−1 of LCF stimulates growth and improves protein retention of polka‐dot grouper whereas higher levels, or the same or higher levels of MCF, depress performance.

Evidence of a metabolic fatty acid-sensing system in the hypothalamus and Brockmann bodies of rainbow trout: implications in food intake regulation

“…Besides their role as an energy source, lipids have been shown to act as important signaling molecules in mammals (28). In fish, high levels of circulating lipids have been traditionally associated with reduced food intake (15,17,32,49,51,56), while more recently, a deleterious effect on glucose homeostasis has been described in rainbow trout fed a high-fat diet (12). However, these effects had never been evaluated before using individual FA.…”

Nutrient Sensing Systems in Fish: Impact on Food Intake Regulation and Energy Homeostasis

“…This occurred for instance in rainbow trout (Peragón et al, 2000; Rasmussen et al, 2000; Gélineau et al, 2001; Forsman and Ruohonen, 2009; Figueiredo-Silva et al, 2012c; Saravanan et al, 2013), chinook salmon (Silverstein et al, 1999), polka-dot grouper (Williams et al, 2006), Senegalese sole (Bonacic et al, 2016) or grass carp (Li et al, 2016). Moreover, enhanced lipid storage is also usually associated with a reduced food intake (Shearer et al, 1997; Silverstein et al, 1999; Johansen et al, 2002, 2003).…”

Oxidation of medium-chain and long-chain fatty acids by polka dot grouper Cromileptes altivelis

“…The dietary lipid was predominantly from either coconut oil for MCFA, or olive oil for LCFA. The diets used were the same diets used in a previous growth assay (Williams et al. 2002b) in which olive oil was chosen as the source of LCFA because of its very low content of n‐3 series of polyunsaturated fatty acids (PUFA) (Table 2).…”

“…Recent studies with polka dot grouper have indicated that this species increased protein retention when 150 g kg −1 , but not 300 g kg −1 fat, in the form of LCFA, was added to the diet. However, when 300 g kg −1 LCFA was added to the diet, or when 150 or 300 g kg −1 MCFA were added to the diet, food intake and growth were severely depressed (Williams et al. 2002b).…”