| Grass carp (Ctenopharyngodon idella) is a native Chinese herbivous freshwater fish which is one of the largest members of the family Cyprinidae. It can be found in almost all large freshwater in China with a broad distribution. It is extensively cultivated in Eastern Asia for food with great commercial value. It also plays an important role in world aquaculture with global annual production being4.010million tons in2006, being as the second biggest contributor to the world fish production (FAO,2006). However, its economic characters seriously declined because of inbreeding, over-fishing and destruction of ecological environment. It is important to achieve sustainable development of the grass carp aquaculture using genetic improvement for the conservation and utilization of genetic resources. Hybridization as an effective means of genetic improvement is used in breeding of grass carp.The breeding technology in pond with zero-discharge is also the hot topics of the current healthy cultivation in pond. In this study, the hybridized offsprings were obtained from different geographic combinations and families of grass carp to analyze the genetic structure and growth differences between dfferent combination families and hybrids of F1and the two age fingerlings.The hearthy breeding technology in pond was also discussed in this paper. The assessment can be briefly summarized as follows:1. Microsatellites analysis on genetic structure in Yangtze River, Zhujiang River, and Yangtze River♀×Zhujiang River(?) groups of grass carp8pairs microsatellite primers were used to study genetic variation of the grass carp in three progeny groups:YZ, YY and ZZ from the populations of Yangtze River and Zhujiang River. The result suggested the number of alleles generated from each locus ranged from two to six. These microsatellite primers could be used as good molecular markers for the genetic variation study of the grass carps. The number of effective alleles (Ne), observed heterozygosity (Ho), expected heterozygosity (He) and polymorphic information content (PIC) in YZ group were the highest which were2.8111,0.9843,0.6399and0.5598respectively. Meanwhile, ZZ group had the lowest values:2.6751,0.8650,0.6129and 0.5283respectively. The UPGMA and NJ trees based on genetic distance demonstrated that YZ group was genetically near to YY group. Fst and AMOVA analysis of all groups and loci indicated that there was moderate differentiation between YY group and ZZ group. The highest genetic diversity existed in YZ indicated this hybrid had the most potential for further breeding. There was obvious divergence between Yangtze River and Zhujiang River populations of grass carp.2. Comparative analysis on growth and morphology in Yangtze River, Zhujiang River, and Yangtze River♀×Zhujiang River(?)groups of juvenile grass carpThree populations were build based on the Yangtze River population and Zhujiang River populations grass carp, including generations of YY (Yangtze River♀×Yangtze River(?)), ZZ (Zhujiang River♀×Zhujiang River(?)) and hybrids YZ (Yangtze River♀×Zhujiang River(?)) with growth and mophmetric parameters measured on50,170days after hatched to study the growth and morphological characteristics of juvenile hybrids of grass carp. The major results were as follows. The orders of the body weight, body length and absolute growth rates (AGR) were YZ>ZZ>YY. The differences among offspring were not significant on50days (P>0.05) while being extremely significant (P<0.01) on170days. The AGR of YZ was20.00%higher than that of ZZ and50.00%higher than that of YYrespectively, there were no significant differences (P>0.05) between YZ and ZZ, but the differences between YZ and YY were significant (P<0.05). YZ showed a significant super-parent vigorous rate (20.09%). There were no significant differences (P>0.05) among three groups in standard length/total length, whereas there were significant differences (P<0.05) in head length/total length, body depth/standard length and body width/standard length. The results showed that the YZ with the characteristics of shorter head, higher and wider body. In short, the new crossbreed YZ is a good variety in growth-performance and physical characteristics.3. The growth comparison between Grass carp hybridization family, inbreeding families and combinations of two age fingerlings.30tails Grass carp were randomly selected as the two age fingerlings from the research of one age fingerlings for growth comparisons between hybridization family, inbreeding family and combination family of grass carp. The results showed:(1) maximum individual appeared in YY2family of ChangJiang river combination and its weight was2105.6g; minimum individual appeared in YZ2hybridization family and its weight was 823.5g;(2) In6families, the average weight of YZ2family was the maximum (1567.3±133.1g) while it was minimum in YY1(1521.3±113.5g), and there was no significant difference between them (P>0.05).(3)The average weight of three combination families was1571.1±158.2g (hybridization combination),1557.5±143.4g (ZhuJiang river combination), and1532.2±132.5(Yangtze River combination). There was no significant difference between three combinations (P>0.05).The results showed that the hybridization combinations and families had no significant growth advantage in two age fingerlings.4. The study of health breeding technology in pond with hybrid juvenile of grass carpThe experiments of Grass carp larvae of1st age fingerlings breeding technology in pond with zero-discharge were processed in three standardization ponds with size of6X666.7m2with whole plant protein fed under80:20model in Wujiang Municipal Aquaculture Co.Ltd with cooperation of the American soybean association for two years.The results showed:(1) the average weight of Grass carp was83.5grams per tail, the average weight of Silver carp was72.7grams per tail, the average food coefficient was1.27;(2) During experimental process, there were no chemicals medicines and large-scale outbreaks of disease and grass carp survival rate arrived at91.8%;(3) In breeding process, Silver carp was only used to control plankton mass and water quality for the purpose of zero-discharge without waste water pumped.;(4) The output value per666.7m2was862.5Yuan which achieved expected effect. |
PDF Full Text Request