Effects of Different Dietary Vegetable Lipid Sources on Health Status in Nile Tilapia (Oreochromis niloticus): Haematological Indices, Immune Response Parameters and Plasma Proteome

SIMPLE SUMMARY: This study presents the effects of different dietary vegetable lipid sources (DLs) on several blood parameters, which may indicate the health status of Nile tilapia (Oreochromis niloticus). The tested DLs had no effects on haematological indices. However, the immune response analysis showed that DLs promoted immune systems via different processes. Dietary polyunsaturated fatty acids (PUFAs) increased expression of several proteins involved in coagulation activity, while saturated fatty acids (SFAs) might influence heme lipid-oxidation. Overall, different DLs had effects on several parameters corresponding to health status in Nile tilapia, and dietary PUFAs appear to promote health in this fish. ABSTRACT: This study aimed to investigate the effects of DLs, including palm oil (PO; an SFAs), linseed oil (LO; n-3 PUFAs) and soybean oil (SBO; n-6 PUFAs) on the health status of Nile tilapia (Oreochromis niloticus) during adulthood. Three experimental diets incorporating PO, LO or SBO were fed to adult Nile tilapia for a period of 90 days, and haematological and innate immune parameters were evaluated. Proteome analysis was also conducted to evaluate the effects of DLs on plasma proteins. The tested DLs had no significant effects on red blood cell (RBC) count, haematocrit, haemoglobin, and total immunoglobulin and lysozyme activity. Dietary LO led to increased alternative complement 50 activity (ACH50), and proteome analysis revealed that PO and SBO enhanced A2ML, suggesting that different DLs promote immune system via different processes. Dietary LO or SBO increased the expression of several proteins involved in coagulation activity such as KNG1, HRG and FGG. Increased HPX in fish fed with PO suggests that SFAs are utilised in heme lipid-oxidation. Overall, DLs with distinct fatty acids (FAs) affect several parameters corresponding to health status in Nile tilapia, and dietary LO and SBO seemed to strengthen health in this species.