Growth performance, fatty‐acid composition, lipid deposition and hepatic‐lipid metabolism‐related gene expression in juvenile pond loach Misgurnus anguillicaudatus fed diets with different dietary soybean oil levels

Abstract

A 10 week feeding trial was conducted to evaluate the effects of different dietary soybean oil (SO) levels on growth performance, fatty-acid composition and lipid deposition in viscera, histology and histochemistry of liver, intestine and hepatic-lipid metabolism-related gene expressions in pond loach Misgurnus anguillicaudatus juveniles. Misgurnus anguillicaudatus (mean ± s.d. mass 0·40 ± 0·01 g) were fed five experimental diets containing SO at different concentrations: 0, 20, 32, 56 and 100% SO and a diet containing 100% fish oil (100% FO). The mass gains and specific growth rates of M. anguillicaudatus fed 20% SO and 100% FO diets were significantly higher than those of the other groups (P < 0·05). The lipid content of viscera and the amount of cytoplasmic vacuolation in the liver increased with incremental dietary SO level. Meanwhile, increasing dietary SO levels up-regulated the messenger (m)RNA levels of lipogenic genes (such as Δ6fad, scd, ppar , fas and srebp-1) and down-regulated the mRNA levels of the lipolytic genes (such as ppar , cpt1, atgl and hsl) in the liver. The percentage of 20:4n-6 significantly (P < 0·05) increased with increasing dietary SO level, which might be correlated with the up-regulation of the mRNA level of Δ6fad. The highest levels of dietary SO, however, had a negative effect on growth performance, lipid deposition of viscera and histology and histochemstry of liver and intestine. The increased lipid accumulation induced by incremental dietary SO level probably occurred through different strategies for lipid metabolism as a result of competition between lipolysis and lipogenesis and between export and import of lipids in this species.

Stearoyl-CoA desaturase (scd1a) is epigenetically regulated by broodstock nutrition in gilthead sea bream (Sparus aurata)

“…More recently, experimental data supported a differential regulation of scd1a in liver and skeletal muscle in a fish strain with a high growth potentiality [11]. In other fish species, it is also well known that lipogenic conditions enhance scd1 expression (carp [35], tilapia [28], pond loach [37]), along with hepatic fat accumulation [28].…”

“…Indeed, in mammals this enzyme increases the fatty acid unsaturation level of lipid depots [31], and is a major regulator of lipid storage in liver and adipose tissue [32][33][34]. Likewise, fish scd1 is differentially regulated by unsaturated and saturated fats [28,[35][36][37], correlating positively with hepatic fat accumulation [28].…”

Dietary lipid level and source affect metabolic responses in hybrid catfish (Pseudoplatystoma reticulatum × Leiarius marmoratus)

“…It is known that dietary lipid source can exert a significant effect on energy flux and thus influence metabolism and body fat deposition (Benedito‐Palos et al, ; Izquierdo et al, ; Mourente, Good, & Bell, ; Pereira et al, ). For instance, dietary n−3 HUFA inhibits fat synthesis and decreases fat accumulation in the liver and whole fish (Cao, Liu, Lao, Tian, & Liang, ; Li et al, ; Ribeiro, Logato, Paula, Costa, Murgas, & Freitas, ). Also, the replacement of fish oil by VO rich in 18:2 n−6 increased lipid deposition in the liver and muscle of blunt snout bream (Li, Liang, Zhang, & Gao, ), shortfin corvina Cynoscion parvipinnis (González‐Félix et al, ) and large yellow croaker Larimichthys crocea (Mu et al, ).…”

“…The liver plays a central role in lipid metabolism, and it is a sensitive organ reflecting dietary lipid changes (Li et al, ). Although fish in this study showed no differences among groups in ALT activity, AST activity was lower in fish fed the 9% L than 18% L diets.…”

“…This is in accordance with what was previously observed in muscle lipid content of this hybrid fed diets with increasing dietary lipid levels (Bernardes et al, 2016), as well as in different fish species, where increased dietary lipid levels generally lead to increased carcass lipid (Company, Calduch-Giner, Kaushik, & Perez-Sanchez, 1999;González-Félix, Maldonado-Othón, & Perez-Velazquez, 2016;Helland & Grisdale-Helland, 1998 It is known that dietary lipid source can exert a significant effect on energy flux and thus influence metabolism and body fat deposition (Benedito-Palos et al, 2009;Izquierdo et al, 2005;Mourente, Good, & Bell, 2005;Pereira et al, 2018). For instance, dietary n−3 HUFA inhibits fat synthesis and decreases fat accumulation in the liver and whole fish (Cao, Liu, Lao, Tian, & Liang, 1997;Li et al, 2018;Ribeiro, Logato, Paula, Costa, Murgas, & Freitas, 2008). Also, the replacement of fish oil by VO rich in 18:2 n−6 increased lipid deposition in the liver and muscle of blunt snout bream (Li, Liang, Zhang, & Gao, 2016a), shortfin corvina Cynoscion parvipinnis (González-Félix et al, 2016) and large yellow croaker Larimichthys crocea (Mu et al, 2018).…”