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United States Department of Agriculture

Agricultural Research Service

Research Project: UTILIZING GENETICS FOR ENHANCING COOL AND COLD WATER AQUACULTURE PRODUCTION Title: Response to selection for bacterial cold water disease resistance in rainbow trout

Authors
item Leeds, Timothy
item Silverstein, Jeff
item Weber, Gregory
item Vallejo, Roger
item Palti, Yniv
item Rexroad, Caird
item Evenhuis, Jason
item Hadidi, Sima -
item Welch, Timothy
item Wiens, Gregory

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: February 2, 2010
Publication Date: June 1, 2010
Citation: Leeds, T.D., Silverstein, J., Weber, G.M., Vallejo, R.L., Palti, Y., Rexroad III, C.E., Evenhuis, J., Hadidi, S., Welch, T.J., Wiens, G.D. 0210. Response to selection for bacterial cold water disease resistance in rainbow trout. Journal of Animal Science. 88:1936-1946.

Interpretive Summary: Stakeholders in rainbow trout aquaculture have expressed concern about losses attributable to Flavobacterium psychrophilum, the bacterium that causes bacterial cold water disease (BCWD). Recent research efforts in Denmark and at the National Center for Cool and Cold Water Aquaculture (NCCCWA) have provided evidence that resistance to BCWD is a heritable trait in rainbow trout. Based on these observations, scientists at the NCCCWA initiated a selective breeding program in 2005 to improve BCWD resistance. The current report describes improvement in BCWD resistance after two generations of selective breeding. Compared to randomly-mated control fish, survival rate in the improved line increased 25 and 45 percentage points after one and two generations of selective breeding, respectively. Breeding values, which describe the genetic merit of individuals used as parents, increased 19 percentage points per generation in the improved line our results suggest that selective breeding can be an effective approach for improving resistance to experimental BCWD challenge in domesticated populations of rainbow trout, and substantial genetic gains can be made with only a minimal increase in inbreeding.

Technical Abstract: A family-based selection program was initiated at the National Center for Cool and Cold Water 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 proportional-hazards 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.

Last Modified: 10/25/2014
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