Fat distribution in Atlantic salmon Salmo salar L. in relation to body size and feeding regime

Abstract

Tissue (fillet, viscera and carcass) distributions of fat were examined in Atlantic salmon, Salmo salar L. (≈740→≈1400→≈2000 g) to test the hypothesis that the fillet becomes increasingly important as a fat depot when fish increase in size. The salmon were fed for 11 weeks on either a high‐fat feed (H: ≈39% fat) or a low‐fat feed (L: ≈28% fat), and half of the fish were then subjected to a dietary switch to create four feed treatments (HH, HL, LL and LH). Fillet fat concentration increased with the passage of time, and the fillet also represented an increasing percentage of the body mass (≈48.5→≈55→≈58.5%) as the fish increased in size. As a consequence, the fillet became increasingly important as a fat depot, containing ≈30% of the body fat in the small fish at the start of the experiment, and ≈50% in the fish sampled at the end of the trial. The proportion of fat localised in the viscera was little influenced by either fish size or feeding treatment, and was within the range of 19–25%, whereas the carcass held a decreasing percentage of the body fat stores as fish size increased. There was a highly significant negative correlation between the percentages of body fat found within the carcass (C) and fillet (F): F = 73.589–0.9285C (R2 = 0.973; n = 13). Although the fillet became more important as a fat depot as fish increased in size, the percentage of the body fat reserves found within this tissue appeared to plateau at 50–55%.

Nutrient composition and sensory evaluation of fillets from wild-type Nile tilapia (Oreochromis niloticus, Linnaeus) and a red hybrid (Florida red tilapia × redO. niloticus)

“…This yield was low (25.4%) when compared with the yield of red hybrid and red O. niloticus fillets reported by Garduño (2003) (35.3% and 35.3% respectively) and Garduño‐Lugo et al (2003) (33.4% and 32.0% respectively). There are reports of increased lipid content in tilapia flesh as animals gain weight during culture, as occurs in salmonids (Rasmussen 2001; Jobling & Johansen 2003). In tilapia, the lipid contents of the liver decrease during growth but increase in the fillet (De Silva et al 1997).…”

Effects of Nutrition and Aquaculture Practices on Fish Quality

“…Generally, fat deposits increase with weight irrespective of the feeding; for example, larger fish tend to have higher lipid content. This has already been shown for gilthead sea bream [4], eel [5], catfish species [6], carp [7], and salmonids [8][9][10].…”

Cloning of peroxisome proliferators activated receptors in the cobia (Rachycentron canadum) and their expression at different life-cycle stages under cage aquaculture

“…High-fat feeds can lead to increases in visceral fat (Company et al, 1999), resulting in reduced carcass quality and product yield (Einen and Skrede, 1998). Body fat of farmed salmonids correlates positively with fat concentration of the feed (Rasmussen, 2001) and their body tissue tends to become fattier as the fish grow larger (Jobling and Johansen, 2003). Vertebrates have developed a regulatory system specifically designed to mediate the systemic response to fat depot, utilizing free fatty acids (FFAs) and their metabolites as nutrient messengers to signal adaptations from peripheral tissues.…”