Heritability and response to selection for carcass weight and growth in the Delta Select strain of channel catfish, Ictalurus punctatus

Authors: Bosworth, Brian; Waldbieser, Geoffrey - Geoff; GARCIA, ANDRE - University Of Georgia; TSURUTA, SHOGO - University Of Georgia; LOURENCO, DANIELA - University Of Georgia

Submitted to: Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2019
Publication Date: 9/12/2019
Citation: Bosworth, B.G., Waldbieser, G.C., Garcia, A., Tsuruta, S., Lourenco, D. 2019. Heritability and response to selection for carcass weight and growth in the Delta Select strain of channel catfish, Ictalurus punctatus. Aquaculture. https://doi.org/10.1016/j.aquaculture.2019.734507.
DOI: https://doi.org/10.1016/j.aquaculture.2019.734507

Interpretive Summary: Catfish farming is the largest segment of US aquaculture and research is being conducted to improve production efficiency, including genetic selection to improve important traits of catfish. The breeding program at the Warmwater Aquaculture Research Unit, USDA-ARS, is focused on developing catfish with faster growth and higher carcass yield (the amount of edible meat) with the goal of releasing genetically improved catfish to U.S. farmers. Genetic selection works by choosing genetically better animals as parents that will then produce genetically better, superior performing offspring. Parents are selected based on estimates of their genetic merit for targeted traits. In this study researchers used data on fish performance for carcass weight and growth rate along with information from pedigree relationships to estimate heritabilities (the proportion of differences for a trait in a population due to genetic differences) for carcass weight and growth rate. This information was then used to estimate the breeding value (a measure of the genetic merit) of each catfish in the population and parent fish of the next generations were selected based on having higher genetic merit for these two traits. Estimates of genetic merit show potential for improvement in both traits. Measurements have been recorded on 27,160 fish for growth rate and 6,023 fish for carcass yield. and both traits have been improved in the population after 2 generations of selection. The population being developed is referred to as the Delta Select line of channel catfish and will be released to catfish farmers. Use of this line of catfish by U.S. farmers will benefit catfish producers, processors and consumers.

Technical Abstract: A population of channel catfish (Ictalurus punctatus), referred to as the Delta Selects, was established in 2006 and has been selected for increased growth and carcass yield as part of the USDA’s Warmwater Aquaculture Unit’s mission to develop improved catfish germplasm for release to U.S. catfish farmers. The base population was established from catfish collected from 10 commercial farms. Broodfish were spawned in ponds, full-sib families were reared in separate tanks until tagging at 8 to 10 months post-hatch when fish were reared communally in earthen ponds until 16 to 18 months post-hatch. Fingerling weight, harvest weight and sex were recorded. A sample of males and females from each full-sib family was processed and carcass weight (head and viscera removed) was recorded. Pedigree was determined by assigning offspring to parents based on inheritance of microsatellite alleles. Data was collected on offspring produced in 2008, 2009, 2011, 2012, 2014 and 2015. Various statistical models were compared, and variance components and breeding values were estimated with BLUP F90 software. Selection was based on estimated breeding values for increased harvest weight and carcass yield. Fingerling weight was recorded for 27,000 fish from 945 full-sib families produced by 465 sires and 726 dams; harvest weight was recorded for 27,160 progeny from 954 full-sib families produced by 467 sires and 731 dams; and carcass weight was recorded for 6023 animals from 752 full-sib families produced by 394 sires and 588 dams. Heritabilities estimates were 0.15 for fingerling weight, 0.21 for harvest weight and 0.32 for carcass yield. Genetic correlations were 0.77 for fingerling and harvest weight and 0.20 for carcass yield and harvest weight. Genetic trends, comparison to a randomly bred control line, and correlations between mid-parent EBVs and offspring phenotypes demonstrate positive response to selection for both traits.