Effect of feeding frequency and romet-medicated feed on survival, antibody response, and weight gain of fingerling channel catfish Ictalurus punctatus after natural exposure to Edwardsiella ictaluri.

摘要

The efficacy of restrictive feeding regimes and Romet R-medicated feed (Romet-30 40.5 mg premix/kg feed) fed at 2.0% body weight was evaluated under field trial conditions for the treatment of naturally induced E. ictaluri infections in fingerling channel catfish. After detection of an E. ictaluri epizootic, fish were fed on medicated or non-medicated feed daily, every other day and every third day for the duration of the experiment. Experimental treatments also included fish that were deprived offeed and those provided Romet-medicated feed for 5 consecutive days followed by non-medicated feed fed daily. Feeding frequency and diet significantly affected survival and liveweight gain. Survival was greatest among fish that were completely deprived of feed or fed on medicated feed every other or every third day. The use of non-medicated feed every other or every third day was equally as effective for reducing E. ictaluri-associated mortality as feeding Romet-medicated feed on a daily basis. Feedingfish on Romet-medicated feed for 5 consecutive days was not an effective treatment. Agglutinating antibody titres against E. ictaluri were significantly lower in all groups of fish fed on Romet-medicated feed for the duration of the experiment. The dataindicate that feeding frequency is a primary factor affecting the severity of E. ictaluri infection and that prolonged intake of Romet-medicated feed may suppress antibody production.