Effect of variation in the dietary ratio of linseed oil to fish oil on growth, body composition, tissues fatty acid composition, flesh nutritional value and immune indices in Manchurian trout,Brachymystax lenok

Abstract

In order to study the effects of linseed oil substitution on the growth, body composition, tissue fatty acid composition, flesh nutritional value and immune indices of juvenile Manchurian trout, five feed types containing different levels of linseed oil (LO) mixed with fish oil (FO) were prepared: 0 (0 LO); 250 g/kg (25 LO); 500 g/kg (50 LO); 750 g/kg (75 LO); and 1000 g/kg (100 LO); and fed to juvenile Manchurian trout (initial weight 6.43 ± 0.02 g) for 9 weeks. The results showed that substitution of FO with 750 g/kg LO did not affect the growth of juvenile trout, with protein content in the dorsal muscle, and lipid content in the liver not showing any significant difference (p > 0.05). The highest lipid content found in muscle samples occurred for the 25 LO diet. The fatty acid composition found in the dorsal muscle and the liver of the Manchurian trout reflects the fatty acid composition in the diet, where the relative amount of linolenic acid (ALA), linoleic acid (LA) and docosahexaenoic acid (DHA)found in these organs has a positive linear correlation with their relative composition in the diet (p < 0.05). As the amount of LO in the diet was increased, the composition of ALA found in the sampled organs increased, while the composition of DHA and eicosapentaenoic acid (EPA) decreased. At the same time, the index of atherogenicity (IA) and thrombogenicity (IT) of the muscle samples from the 75 LO and 100 LO diets was significantly lower than for the 0 LO and 25 LO diets (p < 0.05), while the flesh lipid quality (FLQ) in the 100 LO diet was significantly lower than for the other diets (p < 0.05). The aspartate transaminase (AST) activity decreased initially, and then increased, as the level of LO replacement for FO was increased, with the 25 LO diet being significantly lower than for other groups (p < 0.05). The alanine aminotransferase (ALT) activity in serum samples from the 100 LO diet was higher than that from other diets. The lysozyme (LZM) activity in both serum and liver tissue first increased to a peak for the 25 LO and 50 LO diets, respectively, and then decreased as the level of LO was further increased. There was no significant change in the alkaline phosphatase (AKP) activity in the liver samples; however, the acid phosphatase (ACP) activity decreased significantly from the highest value for 0 LO feed group. In conclusion, the composition of fatty acids in the dorsal muscle and the liver was found to be modified by the diets, and with the diet containing less than 750 g/kg LO, being both 378 | YU et al.

Influence of dietary linseed oil as substitution of fish oil on whole fish fatty acid composition, lipid metabolism and oxidative status of juvenile Manchurian trout, Brachymystax lenok

“…The growth performance of fish has been reported previously 31 . Briefly, both the final weight (22.33 ± 0.35 g, mean ± SE) and weight gain for the LO100 diet were significantly lower than for the other diets ( P < 0.05).…”

Effects of dietary LNA/LA ratios on growth performance, tissue fatty acid composition and immune indices in Manchurian trout,Brachymystax lenok

“…The amount of C18 PUFA (LNA + LA) was kept constant in the diets (approximately 55% of the total fatty acid). The diets were made according to method of Yu et al (2019). Briefly, all raw materials were crushed and fully mixed according to the principle of gradual expansion, and then, linseed oil, corn oil and palm oil were fully mixed and added to the dry ingredients.…”

“…The Manchurian trout ( Brachymystax lenok ) is a cold‐water fish distributed in northern China with high economic value. At present, there have been several studies looking at its nutritional physiology (Chang, Niu, Jia, Li, & Xu, 2017; Liu, Gao, Cao, Yin, & Liu, 2018; Yu et al., 2019). Previous experiments showed that VO (which is rich in C18 PUFA) can partly or completely replace FO without affecting the growth and immunity of fish (Liu et al., 2018; Yu et al., 2019).…”

“…At present, there have been several studies looking at its nutritional physiology (Chang, Niu, Jia, Li, & Xu, 2017; Liu, Gao, Cao, Yin, & Liu, 2018; Yu et al., 2019). Previous experiments showed that VO (which is rich in C18 PUFA) can partly or completely replace FO without affecting the growth and immunity of fish (Liu et al., 2018; Yu et al., 2019). However, it is not known whether different LNA/LA ratios in the diet affect the synthesis of LC‐PUFA or its regulation.…”

Effect of alternate feeding with fish oil‐ and peanut oil‐based diets on the growth and fatty acid compositions of European seabass fingerlings ( Dicentrarchus labrax ) in the recirculated systems

“…In the study, the nutritional quality indexes of fillet lipids were calculated according to the formulas below (Dagtekin et al, 2017; Garaffo et al 2011; Kocatepe et al 2019; Yu et al 2018). …”