Effects of dietary lipid levels on lipid deposition and activities of lipid metabolic enzymes in hybrid tilapia (Oreochromis niloticus × O. aureus)

Dojo loach (Misgurnus anguillicaudatus) is one of the most important cultured freshwater fish in several East Asian countries. However, a little information is available in its nutritional requirements. Thus, this study was conducted to evaluate the effects of feeding varying levels of dietary protein and lipid on growth, fatty acid composition and antioxidant‐related gene expressions in juvenile loach. Six practical diets at three levels of protein (30%, 40% and 50%) and two levels of lipid (6% and 12%) were fed to loach juveniles (initial weight 0.40 g) in triplicated groups (20 fish per replicated) for a period of 8 weeks. Results showed that regardless of lipid level, body weight gain of fish was significantly increased with incremental dietary protein level. Meanwhile, feed conversion ratio was significantly decreased by dietary protein levels, and the lowest value was observed in fish fed dietary protein levels of 50%, regardless of dietary lipid level. Moreover, the percentage of 22:6n‐3 in viscera was significantly increased by different protein levels. The expression level of catalase was significantly increased with incremental dietary protein level with both lipid levels. Meanwhile, the expression level of hepatic nuclear factor erythroid 2‐related factor 2 (Nrf2) was downregulated with incremental dietary protein level with 6% of lipid level, but the expression was upregulated with incremental dietary protein level with 12% of lipid level. In conclusion, these data suggested that 6% lipid and 50% protein in diet was optimal for loach during early development stage.

Section: Discussionsupporting

confidence: 87%

Effects of dietary protein and lipid levels on growth performance, fatty acid composition and antioxidant-related gene expressions in juvenile loachMisgurnus anguillicaudatus

Yan

Liang

et al. 2017

“…Absence of any differences in HFD-induced LPL expression has also been reported for red sea bream (Pagrus major) (Liang, Oku & Ogata 2002) and mice (Kirpich et al 2011). In contrast, results from (Han, Wen, Zheng & Li 2011) showed LPL mRNA abundance in liver of hybrid tilapia was elevated by higher dietary lipid. This discrepancy may be due to species, diet composition and feeding regime, etc.…”

Section: Figurementioning

confidence: 57%

“…). In contrast, results from (Han, Wen, Zheng & Li ) showed LPL mRNA abundance in liver of hybrid tilapia was elevated by higher dietary lipid. This discrepancy may be due to species, diet composition and feeding regime, etc.…”

Section: Discussionmentioning

confidence: 75%

Physiological and molecular changes in large yellow croaker (Pseudosciaena croceaR.) with high-fat diet-induced fatty liver disease

Wang

Hou

et al. 2013

Fatty liver disease is regularly observed in cultured large yellow croaker, and the disease leads to lower growth rates and reduced harvest yields. The goal of this study was to achieve a more detailed understanding of the physiological and molecular changes in response to high‐fat diet‐induced fatty liver in large yellow croaker. Large yellow croaker fed a high‐fat diet (HFD) for 9 weeks developed hepatic steatosis characterized by histological observation and significantly increased plasma triglyceride levels and serum alanine aminotransferase (ALT) activities. However, no significant differences in serum total protein, glucose, cholesterol, non‐esterified free fatty acids (NEFA), aspartate aminotransferase, high‐density lipoprotein and low‐density lipoprotein were observed between the normal diet and the high‐fat diet (HFD) group. The fatty acid composition of tissue lipids was not affected significantly by dietary lipid levels. Gene expression analysis demonstrated that the HFD decreased fatty acid synthase expression and increased PPARγ expression, but had no effect on lipoprotein lipase and PPARα expression. These results suggest that the HFD‐induced physiological changes and fatty liver may be due to the alteration of related gene expression. As such, further investigations of the metabolic pathways and differentially expressed genes are of particular significance in the mechanistic study and understanding of HFD‐induced fatty liver disease.

“…Similar changing trend of LPL expression was also found in tilapia (Han et al . ) and darkbarbel catfish larvae (Zheng et al . ).…”

Section: Discussionmentioning

confidence: 99%

Effects of dietary lipid level on growth, fatty acid composition, digestive enzymes and expression of some lipid metabolism related genes of orange-spotted grouper larvae (Epinephelus coioidesH.)

Mai

et al. 2015

A 4‐week study was conducted to investigate the effects of dietary lipid level on growth, fatty acid composition, activities of digestive enzymes and some lipid metabolism related genes of orange‐spotted grouper larvae (Epinephelous coioides). Six isonitrogenous (57% crude protein) diets were formulated to contain graded contents of lipid (5.94%, 9.92%, 13.30%, 17.71% and 21.87% dry weight, respectively) using fish oil as main lipid source. Each diet was fed six times daily to triplicate groups of fish (71 ± 2 mg, 29 DAH). Results showed that the highest SGR and survival of larvae occurred in 17.71% and 13.30% lipid group respectively. The optimal dietary lipid requirement of larval grouper was estimated to be 15.99% based on SGR. Activities of pepsin and lipase were significantly higher in 17.71% lipid group compared to the rest ones. However, the highest activities of trypsin and amylase occurred in 9.92% and 5.94% lipid treatment respectively. The expression of fatty acid synthesis (FAS) decreased significantly with increasing dietary lipid, while the expression of lipoprotein lipase (LPL) and hormone sensitive lipase (HSL) significantly increased first and then decreased significantly. Compared to other treatment, larvae fed diets with 13.30% and 17.71% lipid have a significant higher relative expression of LPL and HSL respectively. Results of this study suggested that larvae fed the diet with appropriate lipid content showed higher growth performance. Moreover, dietary lipid content could also influence both de novo lipogenesis and lipolysis in transcriptional level.