ARS | Publication request: Genomic analysis of the rainbow trout response to crowding

Submitted to: Plant and Animal Genome Conference
Publication Type: Abstract Only
Publication Acceptance Date: October 19, 2010
Publication Date: January 15, 2011
Citation: Rexroad III, C.E., Vallejo, R.L., Liu, S., Castano, C., Yao, J., Palti, Y., Weber, G.M. 2011. Genomic analysis of the rainbow trout response to crowding. Plant and Animal Genome Conference. P630.

Technical Abstract: Genomic analyses have the potential to impact selective breeding programs by identifying markers as proxies for traits which are expensive or difficult to measure. One such set of traits is the physiological responses of rainbow trout to the stresses of the aquaculture environment. Typical stressors can be categorized under handling and overcrowding, sub-optimal water quality parameters, and social interactions. These stressors negatively impact growth, feed intake, feed efficiency, disease resistance, flesh quality, and reproductive performance. In general, fish respond to stress by activating the neuro-endocrine system leading to elevated blood concentrations of cortisol, the principle corticosteroid in salmonids. Plasma cortisol concentration following a ~3 hour confinement has been used as a measure for stress responsiveness in rainbow trout, however, only weak associations with production traits have been identified. Characterization of the stress response of NCCCWA germplasm identified a heritability >46% and a positive correlation between high cortisol response and body weight at 300 days post hatch. To identify the genes affecting stress response, we conducted a genome scan with over 400 loci from the NCCCWA genetic map on a three generation pedigree characterized for stress response. To date, three significant QTL have been observed. The fourth generation of this pedigree (F2s) has been bred to generate true breeding high and low (cortisol) responders (F3s) for use in functional genomic analyses and to facilitate fine QTL mapping. Identification and characterization of the genes affecting stress response will improve our understanding of the genetic and physiological basis of this trait and its impact on other production traits.