Onion (Allium cepa) improves Nile tilapia (Oreochromis niloticus) resistance to saprolegniasis (Saprolegnia parasitica) and reduces immunosuppressive effects of cadmium

Abstract

The present study investigated the protective effects of dietary Allium cepa against Saprolegnia parasitica infections and the amelioration of cadmium-induced immunosuppression in Oreochromis niloticus. Saprolegnia isolates were recovered during an outbreak of saprolegniasis in farmed O. niloticus raised in a poor aquatic environment. Isolates were identified phenotypically as S. parasitica. Results were confirmed further by ITS gene sequencing. Four fish groups were kept in water with cadmium (1.5 mg/L) and fed for 30 days on a diet supplemented with crude or alcoholic extracts of A. cepa using two concentrations (0.5% or 1%). Positive (with Cd) and negative (without Cd) control fish groups were given the basal diet. The 96 h LC50 value of Cd in tilapia was (15.1 mg/L Cd). Fish exposed to Cd showed poor growth performance parameters, abnormal biochemical measurements, impaired immunological responses, and high oxidative stress indicators. Feeding tilapia on A. cepa-supplemented diets enhanced their growth performance (WG, SGR) and improved the nonspecific immune responses (WBCs, total protein, globulins, lysozyme, myeloperoxidase, and antiproteases). The inclusion of A. cepa in the diets reduced the oxidative stress (GST, SOD) and significantly decreased fish mortality after the challenge with S. parasitica. Dietary supplementation with A. cepa reduced cadmium accumulation in fish organs and up-regulated IL-1β and IFNɣ levels. The most favorable benefits were obtained by the addition of 0.5% A. cepa extract. Our results highlight the immunostimulatory properties of A. cepa dietary supplementation for farmed tilapia and recommend its use prophylactically to control saprolegniasis and mitigate cadmium adverse effects.

Host–pathogen interaction unveiled by immune, oxidative stress, and cytokine expression analysis to experimental Saprolegnia parasitica infection in Nile tilapia

“…In the current study, S. parasitica was pathogenic to Nile tilapia, leading to an 86.6% mortality rate. The clinical signs were similar to those reported in previous studies 38 – 42 . Elevated fish mortality might be attributed to the failure in the osmotic balance (hemodilution) and respiratory failure following massive destruction of the epidermis and degeneration of secondary lamella by invasive hyphal growth, histopathologically evidenced.…”

“…In addition, Nile tilapia exposed to S. ferax zoospores (2 × 10 4 spore/L) showed cumulative mortalities of up to 92.5% over 3 weeks 47 . Stueland et al 38 revealed 89 and 31% cumulative mortalities when Atlantic salmons, Salmo salar L. S. declina zoospore (2.5 × 10 6 spore/mL) experimental infection in scaled carp fingerling revealed 55% cumulative mortalities 48 , S. parasitica spores at a concentration of 1.0 × 10 4 zoospores/L were able to induce 80% mortality ten days following challenges 42 , and Kumar et al 49 recorded 100% mortality in Pangasianodon hypophthalmus experimentally infected with S. parasitica zoospores (2 × 10 6 /L).…”

Interaction of dietary garlic (Allium sativum), onion (Allium cepa), and probiotic on the growth performance and health status of juvenile rainbow trout (Oncorhynchus mykiss)

“…Cho and Lee (2012) obtained similar results for juvenile olive flounder (Paralychthys oilvaceus) when onion powder was supplemented at 0, 0.5, 1, 2, 3, and 5% into the trial diets. In literature, the positive effects of probiotics supplementation on the growth of cultured fish are well documented (Dimitroglou et al 2011;Merrifield et al 2010;Elgendy et al 2023). On the other hand, Akrami et al (2015) reported significantly higher weight gain and SGR for beluga (Huso huso) fed diet containing 1% onion powder.…”

Chemical Synthesis of a Polyvinylpyrrolidone-Capped Silver Nanoparticle and Its Antimicrobial Activity against Two Multidrug-ResistantAeromonas Species

“…Bacterial pathogens are considered one of the most significant problems hindering the expansion of the global aquaculture industry [1][2][3]. Motile aeromonads are Gramnegative, motile, facultatively anaerobic bacteria belonging to the family Aeromonadaceae [4][5][6].…”

“…In addition, misuse of antibiotics may enhance the risk of occurrence and transmission of multidrug-resistant bacteria to humans and animals [4]. Terefore, it is crucial to develop innovative methods to control bacterial diseases in aquaculture, such as vaccination, immunostimulants, and nanomaterials [3,7].…”