Synergistic Roles of Linoleic and Linolenic Acids in Regulating Lc-PUFA Biosynthesis and Reproductive Physiology of...

Fatty acids are crucial for steroidogenesis and gonadal development in fish. A 90-day feeding experiment was conducted before maturation to assess the effects of different dietary levels of linoleic acid (LA) and linolenic acid (LNA) on gonadal development and reproductive performance in Channa striata broodstocks. A total of 300 male and female broodstocks were divided into five treatment groups, each with three replicates, using a completely randomized design. The fish were fed five experimental diets that were isonitrogenous (42%) and isolipidic (12%), containing 0% (B0), 0.5% LA + 1% LNA (B1), 0.5% LA + 0.5% LNA (B2), 1% LA + 1% LNA (B3), and 1% LA + 0.5% LNA (B4). Factorial diets were analyzed using two-way ANOVA (LA and LNA as fixed factors), complemented by one-way ANOVA across all five diets. Reproductive parameters (GSI, fecundity, egg size, fertilization, hatching, and larval survival) improved with supplementation and were significantly improved by a dominant LA main effect (P < 0.05), being the highest in fish fed B3. The fertilization rate also showed a significant LA × LNA interaction (P = 0.001). Liver, gonad, and egg n-3 and n-6 Lc-PUFA increased with dietary LA, and a significant LA × LNA interaction governed the DHA/EPA ratio in all three tissues (P ≤ 0.011) and hepatic DHA accumulation (P = 0.005), each higher in B3. Plasma 11-ketotestosterone (males) and 17β-estradiol and vitellogenin (females) were elevated by dietary LA and each showed a significant interaction. Hepatic Δ6/Δ5 fads2 and gonadal cyp17a1 and cyp19a1 responded through individual main effects without any interaction. Overall, dietary LA drove Lc-PUFA accumulation and reproductive output, whereas LA and LNA acted synergistically to elevate the tissue DHA/EPA balance and reproductive endocrine responses. 1% LA with 0.5-1% LNA (B3) most effectively enhanced the reproductive performance of striped murrel broodstock.