Dietary DHA/EPA ratio affected tissue fatty acid profiles, antioxidant capacity, hematological characteristics and expression of lipid-related genes but not growth in juvenile black seabream (Acanthopagrus schlegelii)

Abstract

An 8-week feeding trial was conducted to investigate the effects of dietary docosahexaenoic to eicosapentaenoic acid ratio (DHA/EPA) on growth performance, fatty acid profiles, antioxidant capacity, hematological characteristics and expression of some lipid metabolism related genes of juvenile black seabream (Acanthopagrus schlegelii) of initial weight 9.47 ± 0.03 g. Five isonitrogenous and isolipidic diets (45% crude protein and 14% crude lipid) were formulated to contain graded DHA/EPA ratios of 0.65, 1.16, 1.60, 2.03 and 2.67. There were no differences in growth performance and feed utilization among treatments. Fish fed higher DHA/EPA ratios had higher malondialdehyde (MDA) contents in serum than lower ratios. Serum triacylglycerol (TAG) content was significantly higher in fish fed the lowest DHA/EPA ratio. Tissue fatty acid profiles reflected the diets despite down-regulation of LC-PUFA biosynthesis genes, fatty acyl desaturase 2 (fads2) and elongase of very long-chain fatty acids 5 (elovl5), by high DHA/EPA ratios. Expression of acetyl-CoA carboxylase alpha (accα) and carnitine palmitoyl transferase 1A (cpt1a) were up-regulated by high DHA/EPA ratio, whereas sterol regulatory element-binding protein-1 (srebp-1) and hormone-sensitive lipase (hsl) were down-regulated. Fatty acid synthase (fas), 6-phosphogluconate dehydrogenase (6pgd) and peroxisome proliferator-activated receptor alpha (pparα) showed highest expression in fish fed intermediate (1.16) DHA/EPA ratio. Overall, this study indicated that dietary DHA/EPA ratio affected fatty acid profiles and significantly influenced lipid metabolism including LC-PUFA biosynthesis and other anabolic and catabolic pathways, and also had impacts on antioxidant capacity and hematological characteristics.

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

“…However, in this study, it can be suggested that the insignificant differences in these parameters (SOD, CAT, MDA, TAC) represent a good state of fish while validating that alternative lipids are good potential sources. This means n‐3/n‐6 essentials did not have influences on those antioxidant indicators as previously reported (Jin et al, ; Li et al, ). Speculatively, authors suggest the EPA/DHA ratios were at levels that could neither cause any destruction to the immune oxidative defence system of fish.…”

Oxidative status and intestinal health of gilthead sea bream (Sparus aurata) juveniles fed diets with different ARA/EPA/DHA ratios

“…1 OTUs: Average number of operational taxonomic units. 2 Margalef species richness: d = (S − 1)/log(N) where S is the number of species, and N is the total number of individuals in the sample. 3 Shannons diversity index: H' = − ∑(pi(lnpi)) where pi is the proportion of individuals belonging to the ith species present in the sample.…”

Optimizing long chain-polyunsaturated fatty acid synthesis in salmonids by balancing dietary inputs

“…Part of this bigger picture includes understanding the relationship between dietary LC-PUFA input and output, i.e., the rate and quantity of LC-PUFA synthesis and production. Dietary ratios among the LC-PUFA, such as DHA/EPA and EPA/ARA, are also known to influence the phenotypic response, including growth, lipid metabolism, and LC-PUFA synthesis [ 9 , 10 , 11 ]. Defining, and quantifying, optimal dietary ratios to achieve high muscle tissue storage levels of LC-PUFA would be helpful from a production and consumption standpoint.…”