ABSTRACT
Female Culter alburnus was faster in growth rate than males. In this study, the gynogenetic G2 and the pseudo-male G2' were used as the female and male parents, respectively, to breed a new national variety "All-female No.1" C. alburnus (AFC). Hormone induction, embryonic development, gonadal differentiation, and growth of AFC were studied. The results showed induction with low concentrations of 17α-methyltestosterone in a indoor-net cage culture was not effective. Under the stimulation of 17α-methyltestosterone, some gonads had a tendency to transform into testis, but not completely. There were three types of gonads in 5-month-old and four types of gonads in 12-month-old fishes, however, they all differentiated into ovaries in 15-month-old fishes. Testosterone propionate and high concentrations of 17α-methyltestosterone in pond culture induction had a good effect resulting in â a functional pseudo-male with normal testis development that could successfully extrude semen during the breeding period, â¡a pseudo-male with normal testis development, but could not extrude semen, and â¢the appearance of intersexual glands. The second experiment revealed that with common fish, all-female fish embryo had normal embryonic development. The development time and morphological characteristics of each stage were similar, but the development of the all-female embryo was slightly slower than the common embryos. The gonad differentiation of the all-female embryo were normal and none differentiated into testis, which indicated that all-female could ensure the female sex without affecting the normal gonad differentiation. The correlation between body weight, length, and month-age of all-female and common fish was strong. The all-female had faster growth rate and more uniform growth specification than the common fish. Therefore, the use of testosterone propionate and high concentrations of 17α-methyltestosterone in pond culture induction could avoid complete degeneration of gonads into ovaries. The all-female embryo had the advantages of normal embryonic development and gonadal differentiation, faster growth, and uniform growth specification.
ABSTRACT
We explored the effects of different conditions on the artificial incubation of redclaw crayfish eggs in an effort to improve this process. Samples at the egg and juvenile stages were selected. The samples at different stages were separated from the pleopods, then they were placed in incubator boxes and sterilized with different disinfectant solutions. The density was 300,400 and 500 eggs/incubator box, the vibration frequency was 11,16 and 26 vibrations/min, and the water circulation cycle was 2.1, 4.8 and 7.1 cycles/h. The results showed the eggs disinfected with 3000 ppm formaldehyde for 15 min had stronger antioxidant capacity. The hatching and survival rates of five pairs of appendage stage group were significantly lower than those of other groups. In the egg stage, acid phosphatase (ACP) level of compound eye pigmentation stage group was significantly higher than those of other groups. In the juvenile stage, malondialdehyde (MDA) content of five pairs of appendage stage group was significantly higher than those of other groups. The survival rate of 500 eggs/box group was significantly higher than that of other groups. In the egg stage, alkaline phosphatase (AKP) level of 400 eggs/box group was significantly higher than that of other groups. The survival rate of 11 vibrations/min group was significantly higher than that of other groups. In the egg stage, ACP and AKP levels of 11 vibrations/min group were significantly higher than those of 26 vibrations/min group. In the juvenile stage, superoxide dismutase (SOD), ACP and AKP levels of 11 vibrations/min group was significantly higher than those of 26 vibrations/min group. In the juvenile stage, AKP level of 4.8 cycles/h group was significantly lower than that of other groups. In conclusion, egg development at the stage after seven pairs of appendages, with a density of 400 eggs/box, vibration frequencies set at 11 vibrations/min achieved high hatching rates (93.58 %) and survival rates (75.67 %). Moreover, bronopol or hydrogen peroxide might have a better choice to replace formaldehyde if further exploration was conducted to reduce stimulation of the in vitro-grown egg. These conditions could be used on a large scale to optimize the production of redclaw crayfish.
