Effects of replacing fishmeal with Antarctic krill meal on growth and reproductive performance of Litopenaeus vannamei broodstock

This study evaluated the effects of replacing fishmeal with Antarctic krill meal (AKM) on the growth and reproductive performance of Litopenaeus vannamei broodstock. Six isonitrogenous and isolipidic diets were formulated by replacing fishmeal with different proportions of AKM (0% (M1, control), 20% (M2), 40% (M3), 60% (M4), 80% (M5), and 100% (M6)) and fed to L. vannamei broodstock (initial weight: 27.95 ± 0.23 g) for 70 days. Results showed: (1) The weight gain rate (WGR) and specific growth rate (SGR) of the M6 group were significantly lower than the control group ( P  < 0.05). (2) The gonadosomatic index (GSI) of the M2 and M3 groups was significantly higher than the control group ( P  < 0.05). (3) AKM significantly increased triglyceride (TG), total cholesterol (TC), and estradiol (E ₂ ) levels in hemolymph, hepatopancreas, and gonads, elevated progesterone (PROG) in hemolymph, and increased vitellogenin (VTG) in hemolymph and gonads while decreasing VTG in the hepatopancreas ( P  < 0.05). (4) An appropriate replacement level of krill meal significantly reduced gonad-inhibiting hormone (GIH) in the eyestalk ( P  < 0.05), with no significant effect on molting-inhibiting hormone (MIH) ( P  > 0.05). (5) Gene expression analysis revealed that krill meal significantly upregulated ovarian development-related genes ( vtg , vtgr , vasa , e75 , rxr ) and steroidogenesis pathway genes ( star , 3β-hsd , 17β-hsd ) ( P  < 0.05). Polynomial regression analysis of WGR and GSI indicated that the optimal dietary replacement level of fishmeal by AKM was 27.22%-41.78% under the present experimental conditions.