Heritability and response to selection for carcass weight and growth in the Delta Select strain of channel catfish, Ictalurus punctatus
2020
Bosworth, Brian | Waldbieser, Geoff | Garcia, André | Tsuruta, Shogo | Lourenco, Daniela
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, then 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.
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