EFFECTS OF INFECTIOUS PANCREATIC NECROSIS VIRUS (IPNV) ON APPETITE AND GROWTH IN ATLANTIC SALMON, SALMO-SALAR L

The effects of infectious pancreatic necrosis virus (IPNV) infection o n appetite and growth in Atlantic salmon, Salmo salar L., were studied under experimental conditions. Eight groups of 60 fish (age 1 +, init ial weight 172 g) were bath infected with IPNV, while two groups serve d as controls. Virus titres were quantified in kidney and pylorus, bot h prior to the experiment and eight times from 9 to 44 days after infe ction. Feed intake of individual fish was measured using X-radiography at sixteen occasions from 7 to 44 days after infection. During the ex periment, no mortality occurred in the infected or in the control grou ps. In infected fish, the virus titre in both kidney and pylorus incre ased significantly until 16 days after infection, to approximately 10( 6)-10(7) p.f.u. g(-1) tissue, while no virus was detected in the contr ol groups. Between 16 and 44 days after infection, the virus titre in pylorus decreased significantly to a level of 10(3)-10(4) p.f.u. g(-1) . From approximately 20 days after infection, feed intake and specific growth rates were significantly lower in infected fish compared to un infected fish. Few fish completely lost their appetite, and the study revealed that IPNV-infected fish may have relative high virus titres b efore any changes in appetite or growth could be detected. (C) 1998 El sevier Science B.V. All rights reserved.