Statistical model comparison in genetic analysis of challenge test data on Streptococcus agalactiae resistance in Nile tilapia (Oreochromis niloticus)
Master thesis
View/ Open
Date
2016-08-09Metadata
Show full item recordCollections
- Master's theses (IHA) [318]
Abstract
Five statistical models were used to analysis genetic variations, heritability and the ability to predict survival of Nile tilapia based on challenge test data. 12 full-sib Nile tilapia families (1870 individuals) with an average weight of 8g in young group (G8) and 35g in older group (G35) were tested. Sire-dam binary threshold (BTH_sire-dam) model and Animal model (BTH_Animal) were using test-period survival as the univariate trait definition. And sire-dam survival score (SS) model was applied to test-day survival (one record per fish per day). Also a family mean survival (FMS) model and a family mean area (FMA) model were tested with the mean survival rate and integral area per family as trait definitions, respectively. Highest heritability was found with the FMS model (0.56 ± 0.42), followed by the BTH_sire-dam model (0.45 ± 0.17) and the FMA model (0.42 ± 0.34). The BTH_Animal model got a relatively much lower value of heritability (0.27 ± 0.11), whereas the SS model (0.07 ± 0.03) was distinctly the lowest. The highest Pearson correlation coefficients between predicted breeding values for the various models were 0.97 for the BTH_sire-dam model and the BTH_Animal model, 0.96 for the SS model, 0.87 for the FMA model and the FMS model had the lowest prediction power with a correlation of 0.77. In conclusion, BTH_sire-dam model was the best fitted model with a high heritability and the highest selection accuracy among these five models.