The impact of various selenium forms during the maturation period of Gilthead seabream (Sparus aurata) broodstock on the reproductive performance, egg, and offspring quality.

This study investigates the effect of dietary Selenium (Se) supplementation on reproductive performance, fecundity, hatchability, egg and oil droplet size, and serum biochemical parameters in Gilthead Sea Bream (G. Sea Bream, Sparus aurata) broodstock. The study includes three treatment groups: a basal diet (BD) without selenium supplementation (control group, C), a BD supplemented with selenium nanoparticles (Nano-Se) at 0.3 mg/kg, and a BD supplemented with organic selenium (Org-Se) at 4 mg/kg (2 g of crushed yeast; Sel-Plex 2000 mg Se kg-1, Alltech, Lexington, KY). The glutathione peroxidase (GPx) enzyme activity, the characteristic of the egg and offspring, was examined, as well as the survival and growth of the resulting larvae. Nine 15 cubic meters fiberglass tanks were used in the experiment, filled with seawater of a salinity of 36.9 ± 1.1 parts per thousand (ppt). Each tank was stocked with six G. seabream broodstock, maintaining an equal sex ratio (three males and three females). The females’ average weight was 1000 ± 50 g, while the males averaged 400 ± 50 g. The brooders were fed 5% of their body weight three times daily for 84 days, using an equal mixture of 45% crude protein dry feed, squid, and sardine. The broodstock were injected with 10 µg/kg of a Luteinizing hormone-releasing hormone (LHRH) analog after the 84-day feeding period to induce spawning. The levels of reproductive hormones, including luteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone (T), and estradiol (E), in brooders (males and females) fed selenium-supplemented diets with Nano-Se and Org-Se increased. In males fed Nano-Se, the increases compared to the control were 74.8%, 84.8%, and 134.8% for the respective groups. While the males fed Org-Se, the increases were 14.01%, 20.01%, and 26.09%, respectively. However, in Females fed the Nano-Se diet, increases as compared to control were 58.1%, 121.4%, and 98.5%, and in females fed the Org-Se diet, increases were 28.17%, 38.21%, and 55.22% for LH, FSH, and estradiol (E), respectively. Albumin, total protein, and globulin levels, as compared to the control, were also increased in brooders (both male and female) fed the Nano and Organic Selenium diets. In contrast, the brooders (male and female) fed the Nano and Organic Selenium diets exhibited triglycerides, lipids, and cholesterol lower than the control. The total egg number, relative fecundity, final egg and oil droplet diameter, and hatchability were also higher in the brooders fed the Nano and Organic Selenium diets than in the control. Data of the larvae (20 DPH) produced from broodstock fed with diets fortified with different forms of Selenium during the maturation period were also investigated. The larvae from mothers fed the Nano-Se exhibited higher final length, final weight, and survival rates than those fed the Control and Org-Se diets.