Effect of Supplemental Dietary α-linolenic Acid (18:3n-3) on the Growth Performance, Body Composition, and Fatty Acid Profile of Coho Salmon (Oncorhynchus kisutch) Alevins Cultured in Freshwater

Abstract

The present study evaluated the effects of supplemental dietary α-linolenic acid (ALA, 18:3n-3) on growth performance, body composition, hepatic fat metabolizing enzymes, and fatty acid profiles of coho salmon (Oncorhynchus kisutch) alevins cultured in freshwater. Six isonitrogenous and isolipidic experimental diets were formulated to attain different levels of ALA (0.09, 0.41, 0.76, 1.03, 1.32, and 1.68% dry weight) by adding linseed oil in a basal diet, respectively. Each diet was fed to triplicate groups of alevins (50 fish in each tank) with initial mean body weight of 0.352 ± 0.002 g. Fish were reared in a freshwater flow-through rearing system and fed to apparent satiation 4 times daily for 12 weeks. The specific growth rate (SGR) increased with increasing dietary ALA level, which reached the peak at 1.03% ALA group ( p < 0.05 ). The final body weight (FBW) and SGR showed linear, quadratic, and cubic responses with the dietary ALA level. The whole-body crude protein increased with increasing dietary ALA level while lipid content was the opposite trend ( p < 0.05 ). However, the content of crude lipid in the whole-body of fish showed quadratic and cubic responses with the dietary ALA level. In addition, except for fatty acid synthase (FAS), the hepatic enzymes activities of lipoprotein lipase (LPL), hepatic lipase (HL), and malate dehydrogenase (MDH) showed linear, quadratic, and cubic response with the dietary ALA level ( p < 0.05 ) The activities of hepatic LPL and HL in 1.32% ALA group were significantly higher than other groups ( p < 0.05 ). The activities of hepatic MDH and FAS in 1.32% ALA group were the lowest, which were significantly lower than those in ALA groups (form 0.09% to1.03%) ( p < 0.05 ). Except for the content of MUFA, the contents of other fatty acids showed linear, quadratic, and cubic response with the dietary ALA level. The ALA and ∑n-3 PUFA content significantly increased with increasing dietary ALA levels ( p < 0.05 ). These results indicated that dietary ALA actively impacted fish growth performance, hepatic lipid metabolizing enzymes, and muscle fatty acid profile. The cubic regression analysis based on SGR as evaluation indices indicated that the optimal dietary ALA content was 1.33% dry weight of diet for alevins.

Improved growth, body composition, and fatty acid composition in striped catfish juveniles, Pangasianodon hypophthalmus, fed with diets containing different oil sources

“…The LSO-supplemented diet contained a higher content of ALA (16.30%) and total n-3 (16.63%), and this may satisfy the requirement of omega-3 and total n-3 of striped catfish, resulting in better growth of the fish group fed with the LSO diet compared with those of the others. In line with other study, Yu et al (2023) reported that the dietary ALA actively impacted fish growth performance, hepatic lipid metabolizing enzymes, and muscle fatty acid profile of Coho salmon, Oncorhynchus kisutch. In addition, in this study, the LSO diet contained a high level of total n-3 and a medium level of total n-6 (21.24%), which led to a balanced ratio of n-3/n-6 (0.90), while this ratio of the other diets was significantly low, ranging from 0.07 to 0.14.…”

Effects of Five Lipid Sources on Growth, Hematological Parameters, Immunity and Muscle Quality in Juvenile Largemouth Bass (Micropterus salmoides)

“…Similarly, there were no differences in growth performances among the FO, SO and RO groups in our results, which is in line with previous studies on largemouth bass [ 17 , 18 ]. Other studies have proved that ALA can be converted by freshwater fish into LC-PUFA (long-chain polyunsaturated fatty acid), which is the necessary fatty acid for animal normal growth and development [ 36 ]. Combined with higher contents of ALA in FO, SO and RO, these three diets could supply enough substrate to synthesize LC-PUFA and then improve the growth of largemouth bass [ 36 , 37 ].…”

“…Other studies have proved that ALA can be converted by freshwater fish into LC-PUFA (long-chain polyunsaturated fatty acid), which is the necessary fatty acid for animal normal growth and development [ 36 ]. Combined with higher contents of ALA in FO, SO and RO, these three diets could supply enough substrate to synthesize LC-PUFA and then improve the growth of largemouth bass [ 36 , 37 ]. However, the PO and LO groups displayed lower growth performances in our results, which is in line with previously obtained results in European seabass [ 10 ] and bullfrog [ 4 ].…”

“…However, the PO and LO groups displayed lower growth performances in our results, which is in line with previously obtained results in European seabass [ 10 ] and bullfrog [ 4 ]. This may be related to the lower proportion of ALA in PO and LO, which mediates the lack or insufficient amount of dietary ALA, impairing the normal growth and development of fish [ 36 ].…”