Studies on Sperm Cryopreservation and Juvenile Rearing for Fish Seedling Production

Abstract

In this study two major experiments was performed: Milt property and sperm cryopreservation of black porgy Acanthopagus schlegeli and the growth and blood properties of juvenile grey mullet Mugil cephalus reared in seawater and freshwater. Sperm cryopreservation The milt property and sperm cryopreservation in black porgy was estimated. Physical property of milt and biochemical property of seminal plasma were investigated. Physical property was observed to be 7.6 ± 2.8 mL. fish- sperm volume, 17.6 ± 2.1 spz x109 sperm density and 93.5 ± 1.9 spermatocrit. The highest values of seminal plasma were correlated with Na+ and Cl- and the value were 184.6 ± 1.1 and 145.8 ± 3.3 respectively. However the glucose concentration (1.8 ± 1.1 mg/dL or 0.1 ± 1.1 mmol/L) was significantly lower than other biochemical parameters. Sperm cryopreservation in black porgy, two experiment were investigated, first Artificial seminal plasma (ASP) as extender and four cryoprotective agents (DMSO, EG, glycerol and PEG) at 5%, 10%, 15% and 20% concentration and second ASP as extender and three combination of the four CPAs (DMSO + EG, DMSO + GC and DMSO + PEG) at 5%, 10%, 15% and 20% concentration. Spermatozoa activity index (SAI) being higher with 10% DMSO and 10% glycerol (3.4 ± 0.1 and 3.1 ± 0.1, respectively).The highest value in total duration of spermatozoa motility (TDM) was revealed in 10% glycerol and 10% DMSO (22.5 ± 0.7 min and 20.5 ± 0.7 min, respectively). Likewise the survival of spermatozoa was the highest in 10% DMSO and 10% glycerol (81.5 ± 0.7% and 76.0 ± 1.4%, respectively). Spermatozoa activity index 15% DMSO + EG and 15% DMSO + GC showed the highest value (3.4 ± 0.1 and 3.3 ± 0.1, respectively). Total duration of spermatozoa motility was longest in 15% DMSO + GC and 15% DMSO + EG (29.0 ± 1.4 min and 20.5 ± 0.7 min, respectively). The survival percentage of spermatozoa showed higher at 15% DMSO + EG and 15% DMSO + GC (84.0 ± 3.1% and 81.2 ± 2.6%, respectively). No significant different was found (p<0.05) in 10% DMSO between 0.25 mL and 0.5 mL straws size. Juvenile rearing The growth and blood properties of juvenile grey mullet reared in seawater and freshwater was investigated and the results compared. The survival rate was significantly lower in freshwater (28%) than in seawater (100%). Total length, body height and body weight of grey mullet were 16.8 ± 1.2 cm and 49.8 ± 10.4 g, at the beginning of the experiment. After 132 days of rearing, total length of was significant higher (41.6%) in MSW groups than (4.7%) in MFW groups; body weight was also significant higher (143.9%) in MSW than that (-23.3%) in MFW groups. The physical property of blood, hemoglobin was observed significantly higher (6.7 ± 0.7 g/dL) in MSW than that of MFW groups (4.5 ± 0.5 g/dL), likewise hematocrit was significantly higher (35.7 ± 3.5%) in MSW than that in MFW group (17.0 ± 1.0%). Biochemical properties of blood plasma were investigated, and Na+, mg2+, and osmolality was significantly higher in MSW than that of MFW groups. However Cl- and glutamate oxyloacetate transaminase (GOT) was significantly higher in MFW than that of MFW groups, and no significant different was observed for K+, Ca2+, glucose and glutamate pyruvate transaminase (GPT).