Abstract
A feeding trial was carried out to evaluate the effects of substitution of fishmeal (FM) by dietary poultry by-product meal, fermented by Lactobacillus casei and Saccharomyces cerevisiae on growth, intestinal health, microbial composition, immune related cytokines and disease resistance of freshwater crayfish, marron (Cherax cainii) against Vibrio mimicus. Two isonitrogenous and isocaloric diets were formulated by replacing FM protein with fermented poultry by-product meal (FPBM) protein at 0% (Control) and 75% (FPBM), and fed marron for 70 days. The results indicated no significant difference (P > 0.05) in final body weights between two groups of marron, whilst intestinal microvilli number per fold was increased in marron fed FPBM than the control. The 16S rRNA sequences revealed an increased number of Lactobacillus and Streptococcus, and decreased number of Aeromonas at genus level in the distal intestine of marron fed FPBM. Marron fed FPBM showed up-regulated expression of IL-8, IL-10, and IL-17F genes in the distal intestine. Significantly (P < 0.05) increased lysozyme and phagocytic activity, and higher survival was found in marron fed FPBM following a bacterial challenge with Vibrio mimicus. Therefore, it is concluded that FPBM is beneficial to marron in terms of microbial community, immune-related cytokines and disease resistance against V. mimicus.
Highlights
Aquaculture, one of the fastest growing food-producing sectors in the world, produced 80 million tonnes of edible fish valued at USD 231.6 billion in 2016, with crustacean aquaculture contributing 7.9 million tonnes with a value estimated at USD 57.1 billion (FAO, 2018)
Feeding marron with fermented poultry by-product meal (FPBM) had no influence on final body weight (FBW) and specific growth rate (SGR) in the present study
This result is in agreement with a previous study on marron fed PBM supplemented with black soldier fry insect meal and found no variations in growth performance (Foysal et al, 2019a)
Summary
Aquaculture, one of the fastest growing food-producing sectors in the world, produced 80 million tonnes of edible fish valued at USD 231.6 billion in 2016, with crustacean aquaculture contributing 7.9 million tonnes with a value estimated at USD 57.1 billion (FAO, 2018). Several issues such as the development of antibiotic resistant bacteria and the accumulation of antibiotic residues in fish tissue with the potential to be transferred to humans, has resulted in many countries banning the utilization of these drugs in aquaculture production (Pourmozaffar et al, 2019) It has become an research imperative to develop functional aqua-diets through advanced approaches like fermentation, supplementation of immunestimulant, natural therapeutics, probiotics, and micronutrients, to improve the growth performance, and, to enhance immune response and disease resistance against invading pathogens (Siddik et al, 2019b). Dietary incorporation of 25% fermented soybean meal in the diet of freshwater prawn, Macrobrachium nipponense significantly upregulated the mRNA levels of the superoxide dismutase [Cu-Zn] gene (Ding et al, 2015)
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