The effects of increasing dietary levels of soy protein concentrate (SPC) on the immune responses and disease resistance (furunculosis) of vaccinated and non-vaccinated Atlantic salmon (Salmo salar L.) parr

• Published in: Fish & Shellfish Immunology
• Main Authors: Metochis, Christoforos, Spanos, Ilias, Auchinachie, Niall, Crampton, Viv, Adams, Alexandra, Thompson, Kim D
• Other Authors: Institute of Aquaculture, Scottish Salmon Company, FAI Aquaculture Ltd, EWOS Innovation, The Moredun Research Institute, orcid:0000-0002-3299-0630
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2016
• Subjects: Atlantic salmon; Parr; Soy protein concentrate; Vaccination; Immune function; Salmo salar
• Online Access: http://hdl.handle.net/1893/24425; https://doi.org/10.1016/j.fsi.2016.10.016; http://dspace.stir.ac.uk/bitstream/1893/24425/1/MS%20FS%20Immulogy%20%282%29.pdf

Juvenile salmon, with an initial weight of 9g, were fed three experimental diets, formulated to replace 35 (SPC35), 58 (SPC58) and 80 (SPC80) of high quality fishmeal (FM) with soy protein concentrate (SPC) in quadruplicate tanks. Higher dietary SPC inclusion was combined with increased supplementation of methionine, lysine, threonine and phosphorus. The experiment was carried out for 177 days. On day 92 salmon in each tank were bulk weighed. Post weighing eighty salmon from each tank were redistributed in two sets of 12 tanks. Salmon from the first set of tanks were vaccinated, while the second group was injected with phosphate buffer saline (PBS). Salmon were sampled on day 92 (pre-vaccination), day 94 (2 days post vaccination [dpv]/PBS injection [dpPBSinj]) and day 154 (62 dpv/dpPBSinj) of the trial for the assessment of their immune responses, prior to the performance of salmon bulk weights for each tank. On day 154, fish from each tank were again bulk weighed and then seventeen salmon per tank were redistributed in two sets of twelve tanks and intra-peritoneally infected with Aeromonas salmonicida. At Day 154, SPC80 demonstrated lower performance (weight gain, specific growth rate and thermal growth coefficient and feed conversion ratio) compared to SPC35 salmon. Reduced classical and total complement activities for salmon fed diets with over 58% of protein from SPC, were demonstrated prior to vaccination. Reduced alternative complement activity was detected for both SPC58 and SPC80 salmon at 2 dpv and for the SPC80 group at 62 dpv. Total and classical complement activities demonstrated no differences among the dietary groups after vaccination. Numerical increases in classical complement activity were apparent upon increased dietary SPC levels. Increased phagocytic activity (% phagocytosis and phagocytic index) was exhibited for the SPC58 group compared to SPC35 salmon at 62 dpPBSinj. No differences in serum lysozyme activity, total IgM, specific antibodies, protein, glucose and HKM respiratory burst were ...