Dietary sodium propionate enhanced the growth performance, immune-related genes expression, and resistance against Ichthyophthirius multifiliis in goldfish (Carassius auratus)

Sodium propionate (SP) is a short-chain fatty acid that has long been used to improve the growth, physiological and immunological properties of aquatic animals. The aim of the current study was to assess the effect of SP intake on growth, immune-related genes, and resistance against Ichthyophthirius multifiliis in goldfish (Carassius auratus). The juvenile goldfish (initial weight = 8.61 ± 0.01 g) fed on diets supplemented with different levels of 0, 1.2, 2.5, and 5 g/kg diet) of SP for 50 days. At the end of the experiment, the treated fish were exposed to theronts stage of I. multifiliis at 5000 theronts per fish. Results showed that higher final weight, red blood cells (RBC), and white blood cells were seen in fish fed 5 g SP/kg than other treatments (P < 0.05), while no significant differences were seen in Na+ and Cl−1 electrolytes levels. With an increase in the level of SP in the diet, a significant up-regulation was observed in the expression of g-type lysozyme (gLys), interleukin-1β (IL-1ß), inducible nitric oxide synthase (iNOS), and tumor necrosis factor ɑ2 (TNF-ɑ2) genes (P < 0.05). Total numbers of parasite trophonts were also significantly decreased in fish treated with SP (P < 0.05). In addition, values of RBC and Cl−1 increased in the treated fish compared to control one, and lower glucose level was obtained in the treatment groups post-challenge with the parasite infection. These data revealed a positive effect of dietary SP on growth, immune response, and pro-inflammatory related genes and increased disease resistance towards I. multifiliis challenge in goldfish

The blood and mRNA levels of antioxidant-related factors in common carp (Cyprinus carpio) fed p-Coumaric acid

The natural antioxidants are well known for their antioxidative activity without side effects when compared to antibiotics. Hence, the present study aimed at evaluating p-Coumaric acid as an antioxidant additive on the blood and mRNA levels of antioxidant-related factors in common carp (Cyprinus carpio). Fish fed the basal diet supplemented with p-Coumaric at 0, 0.5, 1, and 1.5 g/kg for 56 days, then the serum, intestine, and liver samples were collected. The growth performance of fish fed with CA showed significantly (P 0.05). Serum GPX and TAC were enhanced considerably by p-Coumaric acid regarding the control with the highest being in fish fed 1.5 g/kg diet (P 0.05). The measured SOD in the liver and intestine samples revealed no changes in common carp fed p-Coumaric acid (P > 0.05). GPX was significantly upregulated in the intestine by p-Coumaric acid at 1 or 1.5 g/kg (P < 0.05), whereas the liver GPX was upregulated by p-Coumaric acid at 1.5 g/kg. The mRNA level of the GST gene in the intestine of common carp was upregulated by p-Coumaric acid at 1.5 g/kg, whereas the liver displayed upregulated GST in fish fed 1 g/kg diet. The present study approved the application of p-Coumaric acid as a natural antioxidant for friendly, sustainable aquaculture. © 2020, Springer Nature B.V

Effects of dietary p-coumaric acid on the growth performance, digestive enzyme activity, humoral immunity and immune-related gene expression in common carp, Cyprinus carpio

The efficacy of p-coumaric acid (CA) on growth performance, digestive enzyme activity, humoral immunity and immune gene expressions of common carp (Cyprinus carpio) was tested in the present study. Fish were fed diets supplemented with 0, 0.5, 1 and 1.5 g/kg CA for 56 days. According to regression analysis, specific growth rate (SGR), feed conversion ratio (FCR) and weight gain (WG%) were polynomially related to dietary CA levels. The optimum p-coumaric acid supplementation level, based upon these parameters, was 1.35%–1.44%. Furthermore, dietary CA supplementation at levels of 1.0 and 1.5 g/kg significantly improved the serum immune parameters (total Ig, lysozyme and ACH50). Dietary CA especially at 1.0 and 1.5 g/kg increased the intestinal IL-8 and TNF-α, while not affecting the expression of IL-1β and lysozyme gene. The highest and lowest mortality rates 14 days postchallenge with A. hydrophila were recorded in fish fed control and 1.5 g/kg CA, respectively. In conclusion, the oral administration of CA especially at 1 and 1.5 g/kg inclusion levels has the potential to improve growth performance, digestive enzyme activity and immune responses of common carp. © 2021 John Wiley & Sons Lt

Effects of elephant's foot (Elephantopus scaber) extract on growth performance, immune response, and disease resistance of nile tilapia (Oreochromis niloticus) fingerlings

Medicinal plant has been applied as an alternative strategy for antibiotics and chemotherapeutics for controlling the outbreak of diseases in tilapia farming. In this study, five doses of Elephantopus scaber extract (ESE) were added to the basal diet at 0, 2.5, 5, 10, and 20 g kg−1 feed of Nile tilapia fingerlings (13.92 ± 0.06 g initial weight) in triplicate. After 4- and 8- weeks post-feeding, fish were sampled to determine the effects of the ESE supplemented on fish's growth performance, humoral, and skin mucus immune response. After 8 weeks post-feeding, a challenge test against Streptococcus agalactiae was carried out using 10 fish from each tank. Fish fed ESE showed significantly increased serum lysozyme (SL), serum peroxidase (SP), alternative complement (ACH50), phagocytosis (PI), and respiratory burst (RB) compared to the control group (P < 0.05). The skin mucus lysozyme (SMLA) and skin peroxidase (SMPA) were stimulated in fish fed ESE diets. Dietary inclusion of ESE significantly (P < 0.05) promoted final body weight (FW), weight gain (WG), and specific growth rate (SGR); while a reduction in feed conversion ratio (FCR) was observed in fish fed 5 g kg−1 ESE, after 8 weeks post-feeding. The challenge study indicated that the relative percent survival (RSP) was 38.10%, 76.19%, 66.67%, and 47.62% in Diet 2, Diet 3, Diet 4, and Diet 5, respectively. Among the supplemented groups, dietary of 5 g kg−1 ESE showed significantly higher RPS and the highest resistance to S. agalactiae in comparison with other groups. In conclusion, supplementation of ESE (5 g kg−1) enhanced the humoral and mucosal immunity, promoted growth performance, and improved disease resistance of Nile tilapia against Streptococcus agalactiae

Benefits of Dietary Polyphenols and Polyphenol-Rich Additives to Aquatic Animal Health: An Overview

Polyphenols are plant-derived compounds with known biological activities and potential health benefits. Over the past decade, there are an increasing number of studies have investigated the application of polyphenols and polyphenol-rich additives in aquaculture as functional feed additives. There are several types of polyphenolic compounds such as flavonoids, phenolic acids, lignans, and stilbenes of widely known beneficial influences on the overall performances and immunity of fish, and thereby improving the health status and production of fish farms. This review discusses the beneficial applications, optimum recommended dose, and potential side effects of these natural compounds on the growth performance, proximate body composition, immune responses, disease resistance, reproductive performance, and fillet quality of different fish species. Also, it points out that the biological functions and mechanisms associated with the polyphenolic compounds involved in the pathways of antioxidant and pro-oxidant activities, as well as the modulation of gene expression and different immune parameters. The output of this review article provided overwhelming evidence to support the claim that natural polyphenols can be considered as relatively safe and viable alternatives to synthetic chemical compounds that not only to improve the fish health status but also to enhance the fish quality, productivity, and food safety while reducing the use of chemicals and antibiotics in the aquatic eco-systems. © 2020 Taylor & Francis Group, LLC

The gene regulatory roles of herbal extracts on the growth, immune system, and reproduction of fish

The crucial need for safe and healthy aquatic animals obligates researchers in aquaculture to investigate alternative and beneficial additives. Medicinal herbals and their extracts are compromised with diverse effects on the performances of aquatic animals. These compounds can affect growth performance and stimulate the immune system when used in fish diet. In addition, the use of medicinal herbs and their extracts can reduce oxidative stress induced by several stressors during fish culture. Correspondingly, aquatic animals could gain increased resistance against infectious pathogens and environmental stressors. Nevertheless, the exact mode of action where these additives can affect aquatic animals’ performances is still not well documented. Understanding the mechanistic role of herbal supplements and their derivatives is a vital tool to develop further the strategies and application of these additives for feasible and sustainable aquaculture. Gene-related studies have clarified the detailed information on the herbal supplements’ mode of action when administered orally in aquafeed. Several review articles have presented the potential roles of medicinal herbs on the performances of aquatic animals. However, this review article discusses the outputs of studies conducted on aquatic animals fed dietary, medicinal herbs, focusing on the gene expression related to growth and immune performances. Furthermore, a particular focus is directed to the expected influence of herbal supplements on the reproduction of aquatic animals. © 2021 by the authors. Licensee MDPI, Basel, Switzerland