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Cool Weather Feeding Influences Responses of Channel Catfish to Edwardsiella ictaluri Challenge
Author(s) -
Okwoche Veronica O.,
Lovell Richard T.
Publication year - 1997
Publication title -
journal of aquatic animal health
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.507
H-Index - 52
eISSN - 1548-8667
pISSN - 0899-7659
DOI - 10.1577/1548-8667(1997)009<0163:cwfiro>2.3.co;2
Subject(s) - edwardsiella ictaluri , catfish , ictalurus , biology , zoology , fish <actinopterygii> , feed conversion ratio , weight gain , age groups , ictaluridae , fish mortality , body weight , fishery , demography , endocrinology , sociology
A pond study was conducted from November 1 through April 30 with young (age‐0; average size, 43 g) and market‐size (age‐2; average size, 660 g) channel catfish Ictalurus punctatus to compare three management regimens: No feeding, partial feeding (no feeding in December, January, and February), and continuous feeding according to fish size and water temperature. Weight change, feed conversion ratio, and responses to experimental challenge with Edwardsiella ictaluri were evaluated. No significant difference in weight gain occurred between partially fed and continuously fed fish in either age‐group; average weight increase for fed age‐0 fish was 99% and for fed age‐2 fish was 38%. The nonfed age‐0 fish lost 12.3% and the nonfed age‐2 fish lost 7% of their initial weight. Feed conversion ratios were significantly lower in partially fed fish than in continuously fed fish in both age‐groups. Mortality from E. ictaluri challenge among age‐0 fish was significantly higher in the nonfed fish, but among the age‐2 fish, mortality was significantly lower in the nonfed fish. No difference in mortality rate occurred between partially fed and continuously fed fish in either age‐group. Starvation induced lower antibody production against E. ictaluri antigen in the age‐0 fish but higher antibody production in the age‐2 fish. Phagocytic index was lower in nonfed fish than in fed fish from both age‐groups. This study indicates no benefit from feeding age‐0 and age‐2 channel catfish during December, January, or February if feeding is reintroduced in March and continued through April. Although starvation was immunosuppressive in small channel catfish, it enhanced resistance to bacterial infection in larger fish. However, more research information is needed before reduced feeding can be recommended to enhance resistance of channel catfish to E. ictaluri .