|Wiens, Gregory - Greg|
|Leeds, Timothy - Tim|
|Welch, Timothy - Tim|
Submitted to: World Aquaculture Society Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 11/30/2009
Publication Date: 3/1/2010
Citation: Wiens, G.D., Vallejo, R.L., Leeds, T.D., Palti, Y., Evenhuis, J., Welch, T.J., Rexroad Iii, C.E. 2010. Inheritance of rainbow trout Oncorhynchus mykiss spleen size and correlation with bacterial cold water disease resistance. World Aquaculture Society Meeting 2010. Paper No. 87.
Technical Abstract: Infectious disease causes substantial loss in aquaculture and selective breeding for increased innate resistance offers an attractive strategy for controlling disease. In 2005, the NCCCWA implemented a selective breeding program to increase rainbow trout survival following challenge with Flavobacterium psychrophilum, the causative agent of bacterial cold water disease (BCWD). Previously, we reported a family-based, phenotypic correlation between spleen index (spleen weight normalized to body weight, SI) and family survival following F. psychrophilum challenge for two year classes (2005 and 2006) of rainbow trout. Herein, we report the inheritance of spleen size and the phenotypic correlation in two subsequent generations: year classes 2007 and 2008. In 2007, fifteen families were created from mating disease resistant (R) or susceptible (S) parents. Five RxR, RxS and SxS families were measured for post-challenge survival (n=200 fish per family) and SI (n=20 per family). There was a positive phenotypic correlation (r=0.80) between both traits. In 2008, fifteen families were created from mating high SI (H) and low SI (L) parents. Five HxH, HxL and LxL families were measured for survival (n=120 fish per family) and SI (n=20 or 30 fish per family measured at three times over four months). There was a positive phenotypic correlation (r=0.46) between both traits, albeit lower than 2007 data. Average family SI was consistent over the four-month period (r>0.82) and was highly heritable. In summary, our data indicate a consistent, positive phenotypic correlation between spleen size and F. psychrophilum (strain CSF259-93) post-challenge survival in two separate year classes of rainbow trout measured over two generations. Preliminary segregation analysis gives evidence for major genes influencing spleen size. Rainbow trout populations divergent for immune-organ morphology (spleen size) and BCWD resistance may be useful for the elucidation of the genetic architecture involved in disease resistance.