Genetic line by environment interaction on rainbow trout growth and processing traits

Authors: Cleveland, Beth; Leeds, Timothy - Tim; Rexroad, Caird; SUMMERFELT, STEVEN - Freshwater Institute; GOOD, CHRISTOPHER - Freshwater Institute; DAVIDSON, JOHN - Freshwater Institute; MAY, TRAVIS - Freshwater Institute; CROUSE, CURTIS - Freshwater Institute; Wolters, William; PLEMMONS, BRYAN - Casta Line Trout Farms; KENNEY, P.BRETT - West Virginia University

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2016
Publication Date: 2/16/2017
Citation: Cleveland, B.M., Leeds, T.D., Rexroad III, C.E., Summerfelt, S., Good, C., Davidson, J., May, T., Crouse, C., Wolters, W.R., Plemmons, B., Kenney, P. 2017. Genetic line by environment interaction on rainbow trout growth and processing traits. North American Journal of Aquaculture. 79:140-154. doi:10.1080/15222055.2016.1271846.

Interpretive Summary: The NCCCWA selective breeding program has been breeding rainbow trout for improved growth (Growth Line) for five generations. To date there has been no systematic evaluation of relative growth performance between the Growth Line, the randomly bred control line (Synthetic Control), or commercially available genetic lines. The objective of this study was to evaluate growth and processing traits of Growth Line, Synthetic Control, and commercially available rainbow trout in four unique production environments. Growth performance of the Growth Line was similar to or exceeded all other genetic lines at each environment. Fillet yield and viscera yield were also improved in the Growth Line compared to commercial lines, regardless of rearing environment. These results indicate that improved rainbow trout germplasm selectively bred at the NCCCWA retains superior traits across different production environments and may be of value to U.S. trout producers.

Technical Abstract: Genetic line-by-environment (GxE) interactions were determined for growth and processing traits of five genetic lines of rainbow trout reared in four environments. Genetic lines included 1) mixed pool of 109 families selectively bred for improved growth (Growth Line) at the USDA National Center for Cool and Cold Water Aquaculture (NCCCWA, Kearneysville, WV), 2) mixed pool of 52 randomly bred families (Synthetic Control), and fish from three commercial sources, identified as 3) Commercial A, 4) B, and 5) C. Two study locations (NCCCWA and The Conservation Fund's Freshwater Institute (FI, Shepherdstown, WV) contained all five genetic lines while the remaining two (USDA National Cold Water Marine Aquaculture Center, Franklin, ME) and Casta Line Trout Farm (Goshen, VA) contained only the Growth Line and Commercial A. Fish were pit-tagged and comingled at all locations except at Casta Line where Growth Line and Commercial A were stocked into separate raceway sections. Performance of the Growth Line and Commercial A across all four locations were used to detect GxE interactions. Body weight of the Growth Line was similar to or exceeded Commercial A, with a GxE interaction for growth in fish beyond one year of age (P < 0.05). A weak GxE interaction occurred for condition factor (CF), with the Growth Line generally exhibiting a higher CF than Commercial A. There was a GxE interaction for fillet yield on fish harvested at 500 g or less, with no GxE effect for butterfly yield, viscera yield, or final mortality. Data from all five genetic lines at NCCCWA and FI was used to detect genetic correlations in growth and carcass traits. Significant positive correlations were detected for body weight, condition factor, butterfly yield, and viscera yield, indicating that large differences in genetic potential for growth and these processing traits are not significantly affected by GxE interactions.