The effects of dietary soy protein concentrate (SPC) levels on growth and immune function of Atlantic salmon (Salmo salar L.) parr

Citation

Metochis C, Crampton V, Ruohonen K, Thompson KD & Adams A (2013) The effects of dietary soy protein concentrate (SPC) levels on growth and immune function of Atlantic salmon (Salmo salar L.) parr. First Conference of the International Society of Fish and Shellfish Immunology, Vigo, Spain, 25/06/2013 - 28/06/2013. Fish and Shellfish Immunology, 34 (6), p. 1724. http://dx.doi.org/10.1016/j.fsi.2013.03.269; https://doi.org/10.1016/j.fsi.2013.03.269

Abstract
During the past 12 years, fish nutrition research has focused on the replacement of fishmeal (FM) and fish oil (FO) with more sustainable and cheaper alternative protein and lipid sources. Soy protein concentrate (SPC) as an alternative to FM is considered a premium protein source of great potential because of its competitive price and high nutritional properties; which can substitute high levels of FM without causing enteritis and reducing the susceptibility of Atlantic salmon to diseases. In the current trial four experimental diets, containing 35, 50, 65 or 80 % of the dietary protein from SPC, were fed to Atlantic salmon (Salmo salar L.) parr. Growth and innate immunity were assessed after 8 weeks of feeding, before the fish were vaccinated with a commercial Aeromonas salmonicida vaccine to determine the effects of the diets on their immune response 7 and 34 days post-vaccination. Evaluation of the health status of the fish was performed by measuring basic haematology (haematocrit, total white blood cells and differential leucocyte counts) and several other immune responses (i.e. plasma lysozyme, antiprotease and alternative complement activities, plasma protein, total immunoglobulin M and specific antibody levels and oxygen radical production by head kidney macrophages). Carcass and bone proximate composition, phosphorus and mineral analysis were assessed at the end of the trial. It was shown that the immune response of experimental fish did not appear to be size dependent since the linear decline of fish growth and ash content, with increasing dietary SPC inclusion levels, was not followed by a concomitant decrease in their immune response. Decreased ash levels were attributed to the linear decrease of Ca2+, Mg2+ and Mn2+ with increasing SPC inclusion in the diets. Moreover, feeding Atlantic salmon parr on diets containing up to 65 % dietary protein from SPC enhanced some of the innate immune responses with the diet containing 50% protein from SPC giving the best performance both in terms of growth, carcass and bone composition of the fish and immune response. Diets containing 80% of dietary protein from SPC were still able to promote some non-specific immune responses, but to a lesser degree than diets containing 50 and 65% protein from SPC, however plasma total IgM levels in these fish were found at lower levels than in fish fed the control diet. The impact of high SPC inclusion diets on Atlantic salmon parr health requires further investigation, and validation of the results presented here is planned through subsequent disease challenges.

Keywords
Soy protein concentrate, Atlantic salmon, parr, immune responses, growth

Notes
Output Type: Meeting Abstract

Journal
Fish and Shellfish Immunology: Volume 34, Issue 6