Effects of replacing fish oil with palm oil in diets of Nile tilapia (Oreochromis niloticus) on muscle biochemical composition, enzyme activities, and mRNA expression of growth-related genes

Abstract

Background: Due to the continuous demand for fish coupled with decline in capture fisheries, there is the need to increase aquaculture production to meet the demand. Aquaculture is faced with high cost of feeding since fish oil and fish meal are expensive. In view of this, there are calls to explore alternatives that are cheap and reliable. Objectives: This study on Oreochromis niloticus was conducted to evaluate the effects of replacing fish oil (FO) with palm oil (PO) at 0%, 25%, 50%, 75%, and 100% on muscle fatty acid and proximate composition as well as growthrelated enzyme activities and mRNA expression. Methods: Oreochromis niloticus were fed five experimental diets (33% crude protein and 10% crude lipid) for 8 weeks. Feed had variation in fish oil and palm oil contents. After the 8 weeks feeding trial, five fish were sampled from each tank (15 from each treatment) and euthanized using an excess dose of tricaine methane sulfonate (MS-222 at 200 mg/L). Fatty acid and enzyme activities were analyzed using standard protocols. Also, RT-qPCR was used to quantify the expression levels of selected growth-related genes. Results: Fish fed 25% PO recorded the least muscle protein content and was significantly lower than the group fed 100% PO. Paired box protein 7 (Pax-7) enzyme activity was significantly higher in the group fed 50% PO compared to the groups fed 25% PO and 100% PO, while caplain-3 (Capn-3) was significantly lower in the group fed 0% PO compared to all other groups. There was a significant difference among treatments with respect to mRNA expression of Pax-7 and Capn-3. Group fed 25% PO had significantly lower mRNA expression of Pax-7, while the group fed 75% PO recorded significantly higher mRNA expression of Capn-3 compared to groups fed 0% PO, 25% PO, and 100% PO. Pearson's correlation analysis revealed that Igf-I and Igf-II mRNA expression have significant correlation with n-3 polyunsaturated fatty acids content in muscle. Conclusion: The results suggest muscle protein content could be modified if FO is replaced with PO. Also, mRNA expression of Pax-7 and Capn-3 is affected by replacing FO with PO.

The optimal dietary protein level of large‐size grouper Epinephelus coioides

“…The diets contain 350, 400, 450, 500, 550, and 600 g/kg crude protein, respectively. All ingredients were crushed through forty mesh sieve and thoroughly mixed using the progressive enlargement method as previously described by Ayisi and Zhao (), then added the premixed fish oil and soybean lectithin, hand‐rubbing small grease particles. The diets were processed into 6.0 mm diameter pellets strip by a twin screw extruder (F–26, South China University of Technology, Guangdong Province, China) after mixing uniformly in V‐type vertical mixer.…”

Nutritional and immunological evaluation of Nannochloropsis oculata as a potential Nile tilapia-aquafeed supplement

“…To further investigate how N. oculata regulated lipid metabolism, the expression of genes related to lipid metabolism in the liver was analyzed. Fatty acid metabolism involves anabolic and catabolic processes catalyzed by key enzymes relevant to its transcriptional factors [ 94 ]. Fatty acid synthase ( FAS ) catalyzes the de novo long-chain fatty acid synthesis by converting acetyl-CoA and malonyl-CoA to stearic acid, which is further transformed into monounsaturated fatty acids [ 95 , 96 ].…”

Effects of alternative dietary oils on immune response, expression of immune‐related genes and disease resistance in juvenile Nile tilapia,Oreochromis niloticus

“…The alternative lipids replaced fish oil {FO; control} at 50% {(3FVCO); (3FCO)} and 100% {(VCO); (CO); and 50%VCO + 50%CO (VO)}. Fishmeal, soybean meal, rapeseed meal and wheat meal were finely ground, sieved (80 µm mesh) and thoroughly mixed using the progressive enlargement method as previously described by Ayisi and Zhao (). The mixture of dry ingredients was then mixed with virgin coconut oil, corn oil and fish oil with distilled water in a Hobart mixer, and the resulting moist dough pelleted through a pellet extruder of 1‐mm die.…”

“…Reactions were performed using mini option Real‐time PCR machine (Bio‐Rad). The reaction was performed following protocols as previously described in Ayisi and Zhao () and Livak and Schmittgen (). Primers of both target genes and referenced gene (β‐actin) (Oku, Koizumi, Okumura, Kobayashi, & Umino, ) used for the real‐time PCR are shown in Table .…”