LAUSR

Abstract A 7-month feeding trial was conducted before spawning induction in sterlet (Acipenser ruthenus) broodstock (initial weight 990.3 ± 20.05 g). The effects of dietary fish and vegetable oils were investigated on fatty acid profiles in eggs, hematological characteristics, serum lipid indices, and expression of some lipid metabolism and transport-related genes. Three experimental diets with different levels of fish and vegetable oils were formulated as: FO (100% kilka oil), VO (100% rapeseed oil), and FO + VO (50% kilka oil + 50% rapeseed oil). At the end of the feeding trial, egg samples from ovulating females were collected to examine fatty acid profiles and transcriptional mechanisms involved in lipid metabolism and transport. The broodstock physiological condition was assessed using hematological and biochemical indices. Similar to the diets, oleic acid (18:1n-9) was the most predominant monounsaturated fatty acid among all lipid classes in sterlet eggs. Results revealed that the eggs of the broodstock fed VO diet had the highest ratio of DHA/EPA, while the eggs of the broodstock fed FO + VO or FO diet showed higher ratios of EPA/ARA and DHA/ARA. No changes were observed in the levels of lipoproteins, blood lipid indices or hematological parameters in broodstock. This implies that the examined oil sources did not have any adverse effects on fish health during the feeding trial. Feeding different dietary ratios of VO and FO resulted in altered expression of ApoE and PPARα in the eggs, suggesting that lipid metabolism pathways can be influenced by dietary lipid sources. Compared with broodstock fed FO or FO + VO diet, in eggs from the broodstock fed VO diet the expression of ApoE gene was significantly up-regulated and the expression of PPARα was down-regulated. However, the expression of PPARγ was not significantly different among the dietary treatments. Different expression levels of related genes in treatment with various oil sources demonstrate that ApoE, PPARα, and PPARγ play key roles in lipid metabolism, such that they might perform different functions in lipid metabolism and utilization.