Dietary probiotic supplementation in juvenile rainbow trout (Oncorhynchus mykiss) reared under cage culture production: effects on growth, fish welfare, flesh quality and intestinal microbiota

Abstract

This study was conducted to evaluate the effects of dietary probiotic supplementation on growth performance, fish welfare, sensory evaluation, freshness during ice storage and changes in intestinal microbiota of rainbow trout (Oncorhynchus mykiss). The 9‐week feeding trial was conducted in cages under commercial conditions during the winter season, when water temperature decreased from 14°C to 7°C. Fish were fed either a diet without probiotic supplementation (control) or with 0.2% (2 × 109 CFU kg−1 diet) of multi‐strain probiotic bacteria (Bacillus sp., Pediococcus sp., Enterococcus sp., Lactobacillus sp.). Fish weight was recorded at 0, 2, 4, 6 and 9 weeks. Growth performance was not affected by dietary probiotic supplementation. Alternative complement activity (ACH50) was significantly higher in fish fed the diet with probiotic (58.4 ± 3.7 units mL−1) than in the control group (46.9 ± 3.1 units mL−1) (P = 0.03). Several biochemical markers were altered by the dietary treatment. 7‐ethoxyresorufin‐O‐deethylase (EROD) (P < 0.01), glutathione S‐transferase (GST) (P < 0.001), glutathione peroxidase (GPx) (P < 0.05) increased and lipid peroxidation (LP) (P < 0.01) decreased with dietary probiotic supplementation. Flesh quality and shelf‐life of fish stored on ice was not affected by dietary probiotic supplementation. Probiotic supplementation had a limited effect on the intestinal microbiota. Signal strength of the observed operational taxonomic units (OTUs) differed between the control and treatment samples and could indicate variations in the abundance of certain OTUs. Microbiota adhering to the intestinal mucus varied between sampling points, indicating that changes were associated with water temperature.

Dietary probiotic supplementation improves growth and the intestinal morphology of Nile tilapia

“…Liver is highly adaptive to oxidative damage and main organ used for the studies on the effects of pollutants in fish (Gravato et al, 2006). Conversely to the findings of Ozório et al (2016) in rainbow trout, the hepatic LPO was not reduced in the present study. Similarly, no probiotic influence was observed on the antioxidant enzymes GR, CAT and GPx.…”

“…It is also necessary to attend to the distinct temperatures of the experiments (28°C v. 24.5°C) that can also influence enormously the fish responsiveness. Previous studies on rainbow trout using the same probiotic blend reported an increase on the alternative (Ozório et al, 2016) or total (Giannenas et al, 2015) complement and no significant effect on lysozyme activity. Conversely Ramos et al (2015) observed the significant enhancement of lysozyme while higher but not significantly alternative complement activity.…”

“…Probiotics can also provide nutrients, digestive enzymes (Ray et al, 2012) and enhance the absorptive surface area through longer villi (Pirarat et al, 2011) and longer (Merrifield et al, 2010) and denser microvilli (Standen et al, 2015). Some experiments report the stimulation of systemic innate defences as plasma lysozyme, complement or respiratory burst by probiotic microorganisms (Balcazar et al, 2007) and their implication in the oxidative stress response (Castex et al, 2009;Ozório et al, 2016). As result, animals become more resistant to infectious diseases (Castex et al, 2009) and/or present improved feed and growth performances (Pirarat et al, 2011;Ramos et al, 2015).…”

Phylogenetic and functional characterization of the distal intestinal microbiome of rainbow troutOncorhynchus mykissfrom both farm and aquarium settings

“…; Ozório et al . ), and yet its function within the GI tract of these fish remains poorly understood. The prevalence of this phylotype in both the aquarium and farm‐based fish may suggest that the geographical location of the rearing environment does not impact upon its presence, and that rainbow trout could be a specific host for this microbe.…”

Impact of Diets Containing Plant Raw Materials as Fish Meal and Fish Oil Replacement on Rainbow Trout (Oncorhynchus mykiss), Gilthead Sea Bream (Sparus aurata), and Common Carp (Cyprinus carpio) Freshness

“…Although there is adequate literature examining the freshness of ice-stored rainbow trout [23,24], gilthead sea bream [25][26][27][28], and common carp [24], there are few data of the feeding effects on fish freshness for these species. In the past, there has been some research in regard to partial FM substitution and its effects on rainbow trout and gilthead sea bream's postmortem quality [13,29,30].…”