Replacing fish oil with palm oil: Effects onmRNAexpression of fatty acid transport genes and signalling factors related to lipid metabolism in Nile tilapia (Oreochromis niloticus)

Abstract

This study evaluated the effects of replacing fish oil (FO) with palm oil (PO) on enzyme activities and mRNA expression of lipid transport genes and signalling factors in juvenile Nile tilapia. Nile tilapia (9.34 ± 0.14 g) was fed five experimental diets with FO supplemented with PO at 0%, 25%, 50%, 75% and 100%. Liver was sampled from five fish per tank for analysis of fatty acids, enzyme activities and mRNA expression. Glucose 6‐phosphate dehydrogenase (G6PD) was highly expressed in groups fed higher levels of dietary PO, whilst liver X receptor (LXR) was highly expressed in groups fed lower levels of dietary PO. Groups fed 50% PO, 75% PO and 100% PO had significantly higher levels of G6PD mRNA expression whilst group fed 100% PO had significantly higher level of lipoprotein lipase (LPL) mRNA expression. Groups fed 75% PO and 100% PO recorded higher levels of PPAR‐α mRNA expression whilst higher level of malic enzyme mRNA expression was observed in group fed 75% PO. The mRNA expressions of the above stated genes and enzymes activities are predominantly influenced by dietary n‐3 PUFA and n‐6 PUFA levels. Dietary PO inclusion affected enzyme activities of LXR, PPAR‐α,PPAR‐β, LPL and FABP‐3. Activities of PPAR‐α, PPAR‐β and FABP‐3 were increased by PO inclusion whilst LXR and ELOVL 5 were reduced by PO inclusion. In conclusion, it could be inferred that substituting FO with PO could alter the metabolism pathway of genes such as LXR, G6PD, PPAR‐α, LPL and ME that are involved in the transport of fatty acids.

Tissue Distribution and Nutritional Regulation of Fatty Acid-Binding Proteins (fabps) in Two Marine Teleosts, Turbot (Scophthalmus maximus), and Tiger Puffer (Takifugu rubripes)

“…However, in Senegalese sole larvae at 34 days posthatching, cod liver oil significantly downregulated the fabp3 expression compared to olive oil [53]. In Nile tilapia (Oreochromis niloticus), fish oil also downregulated the fabp3 expression when compared to palm oil [54]. In European sea bass (Dicentrarchus labrax) and grouper (Epinephelus coioides), the dietary lipid source even did not significantly affect the fabp expression [55,56].…”

Replacement of Fish Oil With Groundnut Oil for Developing Sustainable Feeds for Labeo rohita Fingerling

“…In the present experiment, lysozyme activity did not change significantly in diets replacing FO with GO up to 60% and then declined by further replacement of FO with GO at 80 and 100%. Serum lysozyme activity was also found to be unaffected by FO substitution with VOs up to a certain level in gilthead sea bream, Sparus aurata (Montero and Izquierdo, 2010), common carp, C. carpio (Yildirim et al, 2013), Eurasian perch, Perca fluvitalis (Geay et al, 2015), and Nile tilapia, O. niloticus (Ayisi et al, 2018).…”

“…However, the significant differences in filet lipid quality of fish fed diets replacing FO more than 60% were recorded, thus indicating that FO could be replaced by GO in diets of L. rohita fingerlings, either partially or totally. Previous studies where dietary FO replacement by different VOs did not affect the growth performance of freshwater fish include catla, C. catla (Priya et al, 2005), Nile tilapia, O. niloticus (Ochang, 2012;Ayisi et al, 2018), rohu, L. rohita (Karanth et al, 2009), common carp, C. carpio (Ren et al, 2012), freshwater catfish, H. longifilis (Babalola and Apata, 2012), pikeperch, S. lucioperca (Kowalska et al, 2010), darkbarbel catfish, Pelteobagrus vachelli (Jiang et al, 2013), Mozambique tilapia, O. mossambicus (Demir et al, 2014), gibel carp, Carassius auratus gibelio (Zhou et al, 2016), and mandarin fish, Siniperca scherzeri (Sankian et al, 2019). This is because once the requirement of essential fatty acids is satisfied, a significant proportion of FO is spared by VOs without hampering the growth, feed consumption, and utilization efficiency.…”