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Leeds T.D.,U.S. Department of Agriculture | Silverstein J.T.,U.S. Department of Agriculture | Weber G.M.,U.S. Department of Agriculture | Vallejo R.L.,U.S. Department of Agriculture | And 7 more authors.
Journal of Animal Science | Year: 2010

A family-based selection program was initiated at the National Center for Cool and Cold Wa-ter Aquaculture in 2005 to improve resistance to bacterial cold water disease (BCWD) in rainbow trout. The objective of this study was to estimate response to 2 generations of selection. A total of 14,841 juvenile fish (BW = 3.1 g; SD = 1.1 g) from 230 full-sib families and 3 randomly mated control lines were challenged intraperitoneally with Flavobacterium psychrophilum, the bacterium that causes BCWD, and mortalities were observed for 21 d. Selection was applied to family EBV derived from a proportional hazards frailty (animal) model while constraining rate of inbreeding to ≤1% per generation. After adjusting for nongenetic effects, survival rate of select-line families increased by 24.6 ± 6.8 and 44.7 ± 6.7 (cumulative) percentage points after 1 and 2 generations of selection, respectively (P < 0.01). Genetic trend, estimated from a linear animal model that fit genetic group effects, was 19.0 ± 4.1 percentage points per generation and approached significance (P = 0.07). Heritability estimates from the proportionalhazards frailty model and linear animal model were similar (0.22 and 0.23, respectively), and family EBV from both models were highly correlated (-0.92). Accuracy of selection, estimated as the correlation between mid-parent EBV and progeny survival rate, was 0.20 (P < 0.01) for the proportional-hazards frailty model and 0.18 (P = 0.01) for the linear animal model. Accuracy estimates were not different (P = 0.81) between the models. This study demonstrates that selective breeding can be effective for improving resistance to experimental BCWD challenge in rainbow trout. ©2010 American Society of Animal Science. Source

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