Submitted to: Journal of Aquatic Animal Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2003
Publication Date: 3/1/2004
Citation: Genetic effects for response to live Edwardsiella ictaluri, killed E. ictaluri, and stress in juveniles from all crosses among USDA 103, USDA 102, and Norris channel catfish Ictalurus punctatus strains. Journal of the World Aquaculture Society 35:78-86. 2004. Interpretive Summary: Resistance to Enteric Septicemia of Catfish (ESC), a disease caused by the bacterium Edwardsiella ictaluri, was measured in juveniles from all possible crosses among USDA-102, USDA-103, and Norris channel catfish strains. Fish were exposed to live E. ictaluri, and survival and anti-E. ictaluri antibody response were measured 30 days after exposure. Purebred and crossbred USDA-102 strain fish had better survival and lower antibody levels than other genetic groups tested. Additional fish from the same groups used in the live challenge were measured for stress response and for antibody level after being injected with dead E. ictaluri bacteria. There were no differences among genetic groups for antibody response to dead E. ictaluri or response to stress. Differences in survival and antibody response to live ESC challenge were not related to antibody response to dead E. ictaluri or measures of stress. Our results indicate that genetic improvement of ESC resistance should be possible in farm-raised channel catfish, but antibody response to killed E. icataluri or response to stress are not good predictors of ESC resistance.
Technical Abstract: Juveniles from all possible crosses among USDA-102, USDA-103, and Norris strains of channel catfish (Ictalurus punctatus) were compared for survival and anti-Edwardsiella ictaluri antibody after exposure to live E. ictaluri bacterium (isolate S97-887); antibody level after injection with formalin-killed E. ictaluri (S97-887); and pre-stress, post-stress, and stress-recovery serum cortisol levels. Purebred and crossbred USDA-102 strain fish had higher survival (mean of 5 groups = 87%) and lower anti-E. ictaluri antibody (mean of 5 groups = 0.167 OD) 30 d after live E. ictaluri challenge than Norris and USDA-103 strains and their crosses (means for 4 groups = 60% survival and 0.210 OD antibody level). The USDA-102 strain contributed additive and dominance effects for increased survival and lower antibody level after live challenge. Antibody response to killed, i.p. injected E. ictaluri was not different among genetic groups. Serum cortisol level was highest in post-stress fish (35.8 ng/ml), intermediate in stress- recovery fish (10.9 ng/ml), and lowest in pre-stress fish (6.5 ng/ml), but was not different among genetic groups within a treatment. Results indicate that differences exist among genetic groups of catfish for survival and antibody production after live E. ictaluri challenge, but these differences were not related to antibody response to killed E. ictaluri or serum cortisol levels.