Senior Lecturer, Bangladesh Agricultural University
Application of lipids in reproduction of fish
In the present study sperm quality, histological structure of the liver and developmental stages of ovary, level of Ca2+ concentration, embryonic development and larval growth were investigated for the confirmation of the positive effects of PUFAs in reproduction and gonadal maturation of Gangetic leaffish, Nandus nandus and Gourami, Colisa fasciatus. Treated group was fed 1% squid extracted phospholipid supplemented diet whereas controlled group was fed the same except phospholipid. In comparison to the control group, treated group exhibited higher gonadal maturation which resulted in spontaneous spawning. The live sperm count was significantly higher (P<0.01) in treated group compared to control group. During the pick breeding (April) season in case of treated group most of the oocytes were found at nuclear migration and tertiary yolk oocyte stage while in case of control group most of them were found in primary and secondary yolk oocyte stage. During spawning season lipid granules and normal morphological structures of hepatocytes with enlarged nucleus and considerable amount of vacules were observed in case of phospholipid treated fish liver whereas less lipid granules with scattered necrosis and large vacuoles in cytoplasm with polarized nucleus were observed in control group. The serum Ca2+ concentration in treated females were significantly higher (P<0.05) in contrast to the controlled females of both the fishes during the breeding season. The experiment suggests that supplementation of dietary PUFAs eventually improve the spawning performances of fish.