The Impacts of Partial Replacement of Sacha Inchi Seed on Growth Performance, Fatty Acids Composition, Blood Parameters, Histological Changes, and Immune-Related Gene Expression in Nile Tilapia (Oreochromis niloticus)

Abstract

The objective of this study was to determine the effects of partial replacement of fishmeal with sacha inchi seed (SIS) meal on growth performance, fatty acids composition, blood parameters, histological changes, and immune-related gene expression in Nile tilapia. Three iso-nitrogenous and iso-lipidic diets were formulated: a control diet without SIS replacement (SIS0) and two experimental diets with 29 (SIS29) and 54 (SIS54) g kg−1 of SIS replacement. A total of 180 fingerlings Nile tilapia with an average body weight of 11.10 ± 0.02 g/fish were randomly divided into 3 groups with 4 replicates at a density of 15 fish per replicate, and each group was fed one of the three diets to apparent satiation twice daily for 10 weeks. The results showed that dietary inclusion of SIS did not cause significant differences in growth and somatic indices (P > 0.05). However, the SIS29 diet significantly increased the protein efficiency ratio (PER) and apparent digestibility coefficient of dry matter (ADC of dry matter). There were no significant differences (P > 0.05) in hematocrit and red blood cell count, but hemoglobin and white blood cells (WBCs) were significantly increased by SIS replacement (P < 0.05). Dietary SIS inclusion also significantly decreased triglyceride (TAG) and low-density lipoprotein cholesterol (LDL-c) (P < 0.05). The hepatic expression of mRNAs encoding TNFα, Interleukin-1 (IL-1), and TGFα genes was not significantly affected (P > 0.05) by SIS inclusion, although the TNFα mRNA was slightly up-regulated. Whole-body fatty acid profiling demonstrated that the SIS54 group has significantly higher levels of C18:3n-3, 20:5n-3, and total n-3 than other groups. These results suggest that partial inclusion of SIS can improve the nutritional quality by increasing n-3 fatty acid contents without any negative effects on growth performance in Nile tilapia.