|Wise, D - MISSISSIPPI STATE UNIV.|
Submitted to: Annual Meeting World Aquaculture Society
Publication Type: Abstract Only
Publication Acceptance Date: February 19, 1997
Publication Date: N/A
Technical Abstract: Disease losses in channel catfish, Ictalurus punctatus, culture currently account for between 20 and 95% of total losses. Enteric septicemia of catfish (ESC), caused by the bacterium Edwardsiella ictaluri, is a highly virulent, systemic disease responsible for about 50% of all channel catfish disease losses in the southeastern United States. Development of disease resistant stocks of channel catfish through selective breeding may be an important contribution to commercial catfish farming. However, limited information is available on phenotypic variation in ESC resistance, and no information is available on correlations of resistance with other traits. Juvenile channel catfish from seven full-sib families were injected with formalin-killed E. ictaluri or challenged by immersion with live bacteria. Antibody level was measured at days 13, 21, and 28 following injection of formalin-killed bacteria. Non-exposed full-siblings were challenged by immersion, and post-challenge antibody levels were measured after 28 days in survivors. Significant variation in antibody response and survival was found among full-sib families. Antibody level ranged from 0.051 to 0.241, and survival ranged from 15.0 to 94.2%. Antibody level on day 28 in fish injected with formalin-killed bacteria was negatively correlated, -0.93 (p<0.01), with survival in the immersion challenge with live bacteria. The results of this study have important implications for increasing disease resistance through genetic selection. Significant family variation indicates possible genetic variation for ESC resistance, and the correlation between antibody level and survival might allow improvement in ESC resistance through selection of another trait.