Preliminary Studies On Breeding Techniques For Freshwater Shrimp (Macrobrachium Nipponense)

A series of experiments were conducted using oriental river prawn (Macrobrachium nipponense) to evaluate the differences in inheritance and production performance between cultured Macrobrachium nipponense and non-cultured Taihu population. By using two populations, cultured and/or non-cultured, the crosses and back-cross were also performed to evaluate the economic morphological characters and production performance of hybrid F1. And the isozymes were analyzed to evaluate the aberrance on inheritance performance between parents and hybrid F1.The main results were shown as follows:1. By comparing the differences on inheritance and production performance between cultured population and non-cultured Taihu population, the results showed that the egg-carrying shrimps of Taihu population were larger than cultured population. Absolute reproduction and relative reproduction of Taihu population were also larger. The body length and body fatness of self-fertilized F1 of Taihu population were higher than cultured population. There was no difference in morphological characters.2. With an objective to improve the germplasm of the oriental river prawn for aquaculture, we performed reciprocal crosses by using two populations, cultured and/or non-cultured, as hybridization parents, and a backcross of hybrid F1 to the non-cultured population from Lake Taihu. The results showed that reciprocal crosses and backcross provided more young prawn production than that from self-fertilization of cultured or non-cultured populations, and increased statistically significantly in production volume by 20.17% and 25.61%, respectively, compared with those from self-fertilization of non-cultured Taihu population. It was also found that hybrid F1 and backcross progenies showed superior performance in the key economic morphological characters and production performance to both maternal and paternal parents, and significant differences (p<0.05) in fatness, carapace length and width, abdomen length and other characters occurred between cultured population and the progenies of reciprocal crosses and backcross. The net profits per unit area in prawn production with hybrid F1 and/or backcross progenies were three or two times that with cultured population, respectively. Therefore, these results demonstrate that we have produced new oriental river prawn germplasms with modified morphological characters and improved production performance via reciprocal crosses and backcross.3. The isoenzymes for lactate dehydrogenase (LDH), esterase (EST), alcohol dehydrogenase (ADH), malate Dehydrogenase (MDH) from muscles of cultured population, non-cultured Taihu population, and their hybrid F1 were comparatively analyzed by polyacrylamide gel electrophoresis (PAGE) technique. The results showed that all these populations could stably generate two LDH, three EST and four ADH bands, and no obvious difference was found on electropherogram among these three enzymes. As for the MDH isoenzyme, two bands were stably displayed on the electropherogram bands present, however, significant differences in MDH expression level were occurred between parents and hybrid F1.