Effect of Cryptobia salmositica-induced anorexia on feeding behavior and immune response in juvenile rainbow trout Oncorhynchus mykiss.
At 10 degrees C, rainbow trout Oncorhynchus mykiss (n = 13 per group) infected with Cryptobia salmositica Katz, 1951 became anorexic at 3 wk post-infection (w.p.i.), with feed-intake decreasing significantly from 1.33 to 0.94% body weight (b.w.). Anorexia was most severe at 4 w.p.i. (0.80% b.w.), coinciding with peak parasitemia (9.2 x 10(6) parasites ml blood(-1)) and anemia. At 8 w.p.i., fish had recovered their appetite although they still had contained detectable parasites (6.8 x 10(5) parasites ml(-1)) and were anemic (pack cell volume, PCV, of 24.4%). However at 5 degrees C, anorexia occurred at 5 w.p.i. (0.81% b.w.), and was most severe at 7 w.p.i. (0.40% b.w.). At 8 w.p.i. (0.43% b.w.), fish displayed high parasitemia (4.6 x 10(6) parasites ml(-1)) and low PCV (10.8%). Fish at 5 degrees C had lower gastric evacuation (GE) rates (GE48h) than 10 degrees C fish, however there were no differences between infected and naive fish at both temperatures. Before anorexia, there was no significant correlation between mean share of meal (MSM, a measure of how food was partitioned within a group) and coefficient of variation in feeding but this became significant during anorexia (p = 0.02 and p = 0.0002 at 10 and 5 degrees C respectively). Significant correlations were detected between b.w. and MSM before onset of anorexia at 10 degrees C (p = 0.005) and 5 degrees C (p = 0.02); this was maintained at 10 degrees C (p = 0.001) but not at 5 degrees C (p = 0.98). Fish on an anorexic diet (0.93% b.w.) responded well at 10 degrees C to a live C. salmositica vaccine; this could partly be due to constant antigenic stimulation by the live vaccine.
Chin
Adrian
A
Department of Zoology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Guo
Fu Ci
FC
Bernier
Nicholas J
NJ
Woo
Patrick T K
PT
D000704:Analysis of Variance; D000818:Animals; D000855:Anorexia / Q000401:mortality / Q000469:parasitology / Q000662:veterinary*; D004435:Eating; D004797:Enzyme-Linked Immunosorbent Assay; D005247:Feeding Behavior / Q000502:physiology*; D005393:Fish Diseases / Q000276:immunology / Q000469:parasitology* / Q000503:physiopathology; D005766:Gastrointestinal Contents / Q000000981:diagnostic imaging; D006790:Host-Parasite Interactions; D016233:Immunotherapy, Active / Q000662:veterinary*; D016830:Kinetoplastida / Q000276:immunology / Q000502:physiology*; D008264:Macrophages / Q000276:immunology; D008863:Microspheres; D017686:Oncorhynchus mykiss; D011528:Protozoan Infections / Q000276:immunology / Q000503:physiopathology; D011529:Protozoan Infections, Animal; D016052:Protozoan Vaccines / Q000276:immunology*; D011859:Radiography; D016897:Respiratory Burst / Q000276:immunology; D013053:Spectrophotometry; D013696:Temperature; D013997:Time Factors
D016052:Protozoan Vaccines