A comparative study of dietary lipid sources on growth performance, body composition, fillet quality, and nutrient retention in juvenile yellow drum (Nibea albiflora)

Abstract

Vegetable oils (VOs) are promising alternatives for fish oil (FO) in the aquafeed industry. However, high dietary VOs lead to undesirable effects on fish growth performance and health, but little information is known about VOs on fillet quality and nutrient retention. This study compared the impacts of different VOs on fish growth performance, fillet quality, and nutrient retention in juvenile yellow drums (Nibea albiflora). The FO group was used as the control (containing 6% FO), and the other four diets had the same lipid content with 5% FO was substituted by different VOs(soybean oil [SO], linseed oil [LO] rapeseed oil [RO], and palm oil [PO]). Juvenile fish (initial body weight of 5.55 ± 0.02 g) were fed the respective diets for 56 days. Results indicated the replacement of FO by VOs was feasible without affecting the growth performance, body composition, or serum biochemicals. The SO diet significantly increased fillet yield and fillet calcium (Ca) and phosphorus (P) element contents. The PO diet reduced water-holding capacity, and altered fillet texture, but significantly increased fillet n-3 LC-PUFAs retention. This could be attributed to the preferential oxidation of SFAs therefore selectively retained DHA in the fillet. Fillet transcriptome sequencing analysis revealed that compared with the FO group, the upregulated mRNA levels of lipid transport-related genes were found in the SO (fabp4, and cd36) and PO (fabp4, cd36, lcat, acbp, and cav1)groups, whereas lipid synthesis-related (acss, elovl4, acsbg, acsl, and elovl1) and lipolysis-related genes (mgll, hsl, acaa1, abhd5, decr1, acad9, pparα, and cpt1) expression were upregulated in the RO and PO groups, respectively. Weighted gene co-expression network analysis clustered two coexpression modules. One module was significantly and positively correlated with fillet yield (P = 0.01, R = 0.64) and Ca element retention (P = 0.05, R = 0.51), and contained genes related to fillet development (eno3 and tnnt3) and Ca regulation (dhrs7c, mcam, and ocam). The other module included genes related to lipid metabolism (elovl1, scd, tecr, fbn1, thbs1, and mdh1), which was associated with fillet n-3 LC-PUFAs retention. Collectively, these findings demonstrated that SO, LO, RO, and PO can be utilized as alternative lipid sources for FO. Based on transcriptome analysis results, genes related to fillet development, Ca regulation, and lipid metabolism were highlighted. These findings help to understand the relationship between dietary lipid sources and fillet nutrient retention in marine carnivorous fish species.