Prevention of Disease in Salmonids by Vaccination and Dietary Modification

Abstract

Experiments were conducted to investigate vaccination and dietary modification as possible prophylactic measures to minimize bacterial kidney disease (BKD) infection occurrence and severity in Atlantic Salmon. In the nutritional modification studies, a commercial diet and six diets containing various levels of calcium, magnesium, zinc, iron, copper, maganese, cobalt, iodine, and fluorine were fed to post-yearling Atlantic salmon. After administration of different diets, the fish fed the diet high in iodine (4.5 mg/kg feed) and fluorine (4.5 mg/kg) had a lower prevalence of clinical BKD (3.6%) as compared to fish fed the other experimental diets (15-24% BKD prevalence) and the commercial feed (34%). In vaccination trials, post-yearling Atlantic salmon parr administered a 0.1 ml intraperitoneal injection of formalin killed BKD cells emulsified in Freund's complete adjuvant, showed an elevated agglutinating antibody response, and almost complete absence of BKD lesion formation in kidneys.
Prevention of furunculosis was achieved in salmon and trout by vaccination. Injection administration of Aqua Health's “Furogen” a commercial furunculosis bacterin reduced losses from 75-83% in control animals to 2.2-10% in vaccinated fish during laboratory trials. Field evaluation of this bacterin in brook trout demonstrated reduced mortality from 36.1% in controls to 9.7% in vaccinated animals.