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Hlubší náhled do genetických a fenotypových korelací mezi kvantitativními znaky se vztahem k produkci u kapra obecného
ZHAO, Jinfeng
Selective breeding has large potential for genetic improvement of production traits in the aquaculture. However, basic knowledge is lacking about phenotypic and genetic parameters for economically important traits for development of selective breeding programs of common carp. Thus, genetic and phenotypic relationships of production-related quantitative traits were investigated in Amur mirror breed of common carp under the pond management condition. Growth is usually the first goal in breeding programs of different species. Selection for faster growth, may affect muscle fat content but the real change will depend on conditions and slaughter yields and it would not affect survival, susceptibility of fish to koi herpesvirus disease (KHVD). In addition, body weight should be integrated in a selection index to avoid a negative impact on growth when selecting for slaughter yields. Muscle fat content is a production trait playing an important role in biological functions of common carp. Muscle fat of common carp would indirectly increase in all subsequent periods by selection on higher body weight in all periods before the second winter. High muscle fat might not be the best for good overwintering in common carp due to negative genetic correlation between muscle fat content and survival during the second and third growing season and that selective breeding for restricted fat content may increase survival without affecting harvest weight. Survival is an important economic trait related to performance of common carp. Keeping excessive muscle fat, hepatopancreas (HP) fat and protein might be disadvantageous for carp survival, at least under conditions where ability of keeping higher level of HP glycogen and hepato-somatic index (HSI) is better. In addition, selection for higher Fulton's condition factor (FC) after the second overwintering should lead to slight increase of survival. KHVD is currently the most serious threat to global carp farming. Improvement of genetic resistance of carp strains through selection can be the most effective method. Most genetic correlations between KHVD resistance and important production traits (e.g., growth, muscle fat content, winter survival and energy reserves) were insignificant, showing that selective breeding program for important production traits would not affect the KHVD resistance of carp and vice versa. Selection for lower FC, relative head length, relative body height or relative body width, with a more prolonged body shape of Amur mirror carp being associated with higher KHVD resistance and selection for improved slaughter yields could positively affect resistance to KHVD and vice versa. Including FC into selection program of common carp could be advantageous for general fish vitality and performance but may have reverse effect on resistance of fish to KHVD. Slaughter yields are traits of high interest especially for fish species sold in processed form like headless carcass or fillet. Slaughter yields predicting models as well as some simple predictors in common carp recorded using combination of 3D landmarks and ultrasound imagery or ultrasound only were highly heritable and strongly genetically related to real yields and may be used in indirect selection program. Due to good genetic correlations between simple predictors in age of two and three years, selection of Amur mirror carp could be done at size of fish that requires less storage capacity and time. However, it should be remembered that selection for slaughter yields may affect body shape, muscle fat content and resistance of fish to KHVD.
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