Effects of replacing fish oil with Antarctic krill oil on the growth and ovarian development of female Litopenaeus vannamei broodstock

This study examined how replacing fish oil with Antarctic krill oil affects the growth and reproduction of female Litopenaeus vannamei broodstock. Six isonitrogenous and isolipidic diet were formulated to replace fish oil with varying percentages of Antarctic krill oil, specifically at 0% (O1), 20% (O2), 40% (O3), 60% (O4), 80% (O5), 100% (O6). These diets were then administered to L. vannamei broodstock, which had an initial average weight of 24.74 ± 0.13 g, over a 70-day experimental period. Results showed: (1) Antarctic krill oil significantly improved weight gain rate(GR) and specific growth rate (SGR), with the O3 and O6 groups showing markedly above the other groups ( P < 0.05). (2) The gonadosomatic index (GSI)of the O6 group was the highest and significantly greater than the O1, O2, and O5 groups ( P < 0.05). (3) Antarctic krill oil significantly increased triglyceride (TG), total cholesterol (TC), vitellogenin (VTG), and estradiol (E 2 ) levels in hemolymph, hepatopancreas, and gonads, and increased progesterone (PROG), high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), and very-low-density lipoprotein cholesterol (VLDL-C) in hemolymph ( P < 0.05). (4) Antarctic krill oil significantly reduced gonad-inhibiting hormone (GIH) and molting-inhibiting hormone (MIH) in the eyestalk and hemolymph, with the O3 group showing the lowest eyestalk GIH, eyestalk MIH, and hemolymph MIH, and the O6 group showing the lowest hemolymph GIH ( P < 0.05). (5) Gene expression analysis revealed that Antarctic krill oil significantly upregulated ovarian development-related genes ( vtg , vtgr , vasa , e75 , rxr ) and steroidogenesis pathway genes ( star , 3β-hsd , 17β-hsd ) ( P < 0.05). In conclusion, replacing fish oil with Antarctic krill oil in broodstock diets beneficially modulated growth-related responses, lipid metabolism, endocrine regulation, and ovarian development in female Litopenaeus vannamei . Under the present experimental conditions, 40% replacement was appropriate for improving growth-related responses, whereas full replacement appeared more favorable for ovarian development.