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Odhad genetické variance užitkových vlastností kapra obecného s cílem předpovědět potenciál selekčního šlechtění v rybničních podmínkách chovu
PRCHAL, Martin
The main aim of this thesis was to study the genetic variation of several performance traits under pond management conditions and to estimate future perspective of sustainable selective breeding program in common carp. In the present study, Amur mirror carp (AM) and Hungarian synthetic mirror carp (HSM) were used. Most of the studied performance traits showed sufficient genetic variation (h2 = 0.12 1.0), suggesting a good potential for genetic improvement of the traits through selective breeding. It was shown that selection of common carp under pond management conditions should be optimally applied after the second overwintering. Winter survival is often a bottleneck for common carp production. As a result, the genetic background of winter survival and traits that might be correlated to the survival was studied. Main focus was given to the muscle fat and body weight and their dynamics through winter period and successive third growing period. It was found that selection for i) lower fat content before and after winter, ii) lower decrease in muscle fat content and/or body weight during winter, iii) higher condition factor may lead to better survival during both winter and third growing period and growth of fish during the third growing season. Unfortunately, direct selection for slaughter yields is impossible on live breeding candidates. Therefore, morphological predictors that can be measured in vivo are considered as an interesting alternative. As a result, external and internal measures were combined on 1553 fish by linear regression to predict log-log residuals (Logr) of slaughter yields. It was found that the accuracy of the prediction of slaughter yields may be solid. From the genetic point of view, model-predicted (h2 = 0.48 0.63) and even individual predictors (h2 = 0.34 0.72) of slaughter yields were highly heritable and favourably genetically correlated to the Logr yields. Hence, selection on trait predictors has an interesting perspective for genetic improvement of slaughter yields in common carp. Furthermore, genetic parameters of fillet fatty acid content and performance traits in market size common carp cultured under semi-intensive pond conditions were estimated. For flesh FA composition analysis 158 individuals were processed. Heritability estimates of total muscle fat, some FA groups and most performance traits were moderate to high (0.23 0.62). Interestingly, genetic correlations showed that genetic improvement of growth via selective breeding under Central European pond conditions without changing the production technology would very likely negatively affect carp flesh quality with respect to FA composition. Finally, restriction-site-associated DNA sequencing (Rad-seq) was used to identify and genotype single nucleotide polymorphism (SNP) markers for subsequent parentage assignment, construction of a medium density genetic map (12,311 SNPs), and testing of efficiency of marker-assisted (MAS) and genomic selection (GS) for growth and Koi herpes virus (KHV) resistance. No genome-wide significant QTL was identified for growth. However, genomic prediction of its breeding value may outperform the traditional pedigree-based prediction, resulting in an 18% improvement in prediction accuracy. On the other hand, genome-wide significant QTL affecting resistance to KHV was identified on linkage group (LG) 44 explaining approximately 7% of the additive genetic variation. The presented results add further evidence supporting the application of selective breeding in common carp cultured even under traditional pond management conditions. However, it is evident that the rearing technology will need suitable modifications. In addition, real economic impact of selective breeding on carp culture should be verified by calculation of realized heritabilities, real genetic gains and the total fish biomass yield of genetically improved stocks from a pond area unit.
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