Dietary Cinnamon Successfully Enhanced the Growth Performance, Growth Hormone, Antibacterial Capacity, and Immunity of European Sea Bass (Dicentrarchus labrax)

Effect of paprika extracts on growth performance, haemolymph chemistry, intestinal microbiota and antioxidant enzyme activities of white-leg shrimp (Litopenaeus vannamei)

This study aims to evaluate the effects of paprika extract on the survival rate, growth performance and stimulation of the innate immune system of Litopenaeus vannamei. In this experiment, 240 healthy shrimp (3.22 ± 0.12 g) were randomly divided into four groups. The shrimp were fed diets with different concentrations of paprika oil extracts (0%, 0.5%, 1% and 2%) for 8 weeks. The results showed that growth performance, urea, uric acid, creatinine, cholesterol levels, aspartate aminotransferase and alkaline phosphatase activities were not significantly affected by adding paprika extract to the shrimp diet (p > 0.05). Diets containing 1% and 0.5% paprika extract showed the highest levels of total protein and triglyceride, respectively (p < 0.05). There was a significant decrease in haemolymph glucose concentration in shrimp-fed diets containing 1% and 2% paprika extract (p < 0.05). Moreover, a diet containing 0.5% paprika extract resulted in the highest levels of total heamocyte count, hyaline cells and large-granular cells in shrimp (p < 0.05). Higher catalase and superoxide dismutase activities were also exhibited in the paprika groups (p < 0.05). Vibrio sp. bacteria were not significantly reduced by paprika extract in the intestines of L. vannamei (p > 0.05). A significant decrease in heterotrophic bacteria was observed with increasing extract concentrations (p < 0.05). The shrimp culture industry can utilize paprika extract as a cost-effective, efficient and environmentally friendly immune stimulant at a concentration of 0.5%.

Effect of cinnamon essential oil dietary supplementation on the growth, fatty acid composition, and meat quality of tilapia

This study was conducted to investigate the effects of dietary supplementation of 0%, 0.2%, 0.35%, and 0.5% cinnamon essential oil on growth performance, fatty acid, and fillet quality of tilapia (Oreochromis niloticus). The results of growth experiments showed that the weight gain rate linearly and quadratically increased with increasing cinnamon essential oil doses (p < 0.05). The results of fatty acids experiments showed that the addition of essential oil significantly decreased the saturated fatty acids levels from 36.67% to 30.82% and increased the polyunsaturated fatty acids (PUFA) levels from 24.55% to 46.89%; especially, the n - 3 PUFA of 0.5% essential oil treatment showed the highest levels. Moreover, the n - 6 PUFA of 0.2% essential oil treatment were increased from 22.17% to 32.99%. The results of fillet quality experiments showed that the hardness and cohesiveness were linearly and quadratically increased with the increasing essential oil doses on days 4 and 7, respectively. The b* values linearly and quadratically decreased as the doses increased on day 7 (p < 0.05). The total volatile basic nitrogen levels were quadratically decreased with increasing cinnamon essential oil doses on day 7 (p < 0.05). In general, it can be concluded that cinnamon essential oil presented positive effects on the growth, nutritive values, and meat quality in tilapia.

Growth Performance and Disease Resistance against Vibrio parahaemolyticus of Whiteleg Shrimp (Litopenaeus vannamei) Fed Essential Oil Blend (Phyto AquaBiotic)

Acute Hepatopancreatic Necrosis Disease (AHPND) is a serious and emerging disease caused by a group of strains of Vibrio parahaemolyticus and affects farmed shrimp, particularly whiteleg shrimps (Liptopenaeus vannamei). The objective of this study is to assess the effect of dietary supplementation with two dosages of an essential oil mixture (Phyto AquaBiotic, abbreviated as PAB) on growth performance and mortality reduction after challenge against V. parahaemolyticus. PAB was mixed with basal diets at rates of 0, 1 and 2 g/kg and fed for 42 days. Each tank was stocked with 100 individuals with experimentation performed in triplicate. The results showed an improvement in growth performance in a dose-dependent manner, specifically regarding daily weight gain, specific growth rate and total biomass, which were significantly improved compared to control (p < 0.05). Further, PAB significantly reduced mortalities when challenged against Vibrio parahaemolyticus (p < 0.05) and decreased Vibrio spp. count in the hepatopancreas of infected shrimp. Overall, PAB was efficient in reducing mortalities in cases of disease outbreaks at a rate of 2 g/kg.

Effect of dietary celery (Apium graveolens) on the growth performance, immune responses, and bacterial resistance against Vibrio anguillarum of European seabass (Dicentrarchus labrax)

In this study, we evaluated to reveal the effects of aqueous methanolic extract of celery (Apium graveolens) on the growth performance, immune responses, and resistance against Vibrio anguillarum in European seabass (Dicentrarchus labrax). For this purpose, twenty fish (initial mean weight of 4.80 ± 0.06 g) were placed into twelve tanks (400 L) in triplicate and fish were fed with control (C) and three different levels (0.01, 0.05, and 0.1 g/kg) of A. graveolens (AG) extract-containing diets (AG0.01, AG0.05, and AG0.1) for 30 days. Blood and tissue (kidney, spleen, and intestine) samples were taken from the fish every 10 days during the study to determine the immune responses of the fish. Respiratory burst activity (RBA) was significantly decreased in the AG0.1 group compared to all other groups on the 10th day of the study (P < 0.05). Significance was noticed in the RBA of fish in all AG groups compared to the C group (P < 0.05) on the 30th day of the experiment Lysozyme activity (LYS) was raised on the 10th day of the study in all celery groups compared to the C group (P < 0.05). No differences in the myeloperoxidase activity (MPO) were observed among the experimental groups (P > 0.05). The final mean weight (FMW) was not affected in any experimental groups (P > 0.05). However, in the AG0.05 group, the specific growth rate (SGR) increased, and the feed conversion ratio (FCR) decreased compared to other groups (P < 0.05). IL-1β in the kidney was highly elevated in the AG0.01 group on the 20th day of the study (P < 0.05). Similar results were observed on IL-6, IL-8, and TNF-α expression in the kidney (P < 0.05). Anti-inflammatory responses (IL-10 and TGF-β) also increased in all experimental groups and tissues compared to the C group (P < 0.05). COX-2 was upregulated on the 20th day of the study in all tissues (P < 0.05). At the end of the feeding trial, the survival rate of the AG0.1 group in fish infected with Vibrio anguillarum infection was higher than the C group. Dietary celery extract did not affect growth performance directly but increased innate immune responses and a high survival rate. Overall, compared to the control group, the growth, immunity, and resistance of European seabass fed with a diet containing 0.05 g/kg celery aqueous methanolic extract has been improved, and this could be used as an immunostimulant feed additive.

The effects of coriander (Coriandrum sativum) seeds on the growth performance, growth hormone, antibacterial capacity, and immune response of European sea bass (Dicentrarchus labrax)

Coriander seeds are among the functional herbal supplements, but their effects on aquatic animals are still lacking. Herein we evaluated the effects of coriander seeds on the growth performance, growth hormone, antibacterial capacity, and immune response of European sea bass (Dicentrarchus labrax). Fish with initial mean weights of 5.08 ± 0.12 g/fish were allocated in four groups (in triplicate) and fed dietary coriander at 0, 5, 10, and 20 g/kg for 150 days. The growth performance, feed utilization, and survival rate of fish-fed dietary coriander meaningfully increased (P<0.05). The protein efficiency ratio gradually increased (P<0.05) in fish-fed coriander seeds compared with the control. On the other hand, the feed conversion ratio was gradually decreased (P<0.05) in fish-fed coriander seeds comparing with the control. The survival rate was markedly increased (P<0.05) in European sea bass-fed dietary coriander regardless of the inclusion level. Further, no differences were seen among fish fed varying levels of coriander (P<0.05). The level of blood growth hormone was markedly higher (P<0.05) in European sea bass-fed dietary coriander at 20 g/kg than fish-fed 0 and 5 g/kg. The abundance of intestinal Vibrio spp. and Faecal Coliform were obviously lower (P<0.05) in fish fed 10 and 20 g/kg than fish fed the coriander-free diet. Further, fish fed 20 g/kg had lower (P<0.05) Vibrio spp. and Faecal Coliform counts than fish fed 10 g/kg. Fish fed dietary coriander had significantly higher (P<0.05) hematocrit, hemoglobulin, red blood cells (RBCs), and white blood cells (WBCs) than fish fed the control. The lysozyme and phagocytic activities were meaningfully increased (P<0.05) in fish fed 10 and 20 g/kg compared with fish fed 0 and 5 g/kg of dietary coriander. In conclusion, dietary coriander could be included in the diets at 10–20 g/kg to improve the growth performance, growth hormone, feed utilization, and immune response of European sea bass.

Experimental Studies on the Impact of the Projected Ocean Acidification on Fish Survival, Health, Growth, and Meat Quality; Black Sea Bream (Acanthopagrus schlegelii), Physiological and Histological Studies

Simple Summary

This study’s data suggest that under the projected scenarios of ocean acidification by 2100 and beyond, significant negative impacts on growth, health, and meat quality are expected, particularly on black sea bream, and will be susceptible to the scientifically approved fish having a weaker resistance to diseases and environmental changes if CO₂ emissions in the atmosphere are not curbed. Knowing the expected consequences, mitigation measures are urgently needed.

Abstract

Acidification (OA), a global threat to the world’s oceans, is projected to significantly grow if CO₂ continues to be emitted into the atmosphere at high levels. This will result in a slight decrease in pH. Since the latter is a logarithmic scale of acidity, the higher acidic seawater is expected to have a tremendous impact on marine living resources in the long-term. An 8-week laboratory experiment was designed to assess the impact of the projected pH in 2100 and beyond on fish survival, health, growth, and fish meat quality. Two projected scenarios were simulated with the control treatment, in triplicates. The control treatment had a pH of 8.10, corresponding to a pCO₂ of 321.37 ± 11.48 µatm. The two projected scenarios, named Predict_A and Predict_B, had pH values of 7.80-pCO₂ = 749.12 ± 27.03 and 7.40-pCO₂ = 321.37 ± 11.48 µatm, respectively. The experiment was preceded by 2 weeks of acclimation. After the acclimation, 20 juvenile black sea breams (Acanthopagrus schlegelii) of 2.72 ± 0.01 g were used per tank. This species has been selected mainly due to its very high resistance to diseases and environmental changes, assuming that a weaker fish resistance will also be susceptibly affected. In all tanks, the fish were fed with the same commercial diet. The seawater’s physicochemical parameters were measured daily. Fish samples were subjected to physiological, histological, and biochemical analyses. Fish growth, feeding efficiency, protein efficiency ratio, and crude protein content were significantly decreased with a lower pH. Scanning electron microscopy revealed multiple atrophies of microvilli throughout the small intestine’s brush border in samples from Predict_A and Predict_B. This significantly reduced nutrient absorption, resulting in significantly lower feed efficiency, lower fish growth, and lower meat quality. As a result of an elevated pCO₂ in seawater, the fish eat more than normal but grow less than normal. Liver observation showed blood congestion, hemorrhage, necrosis, vacuolation of hepatocytes, and an increased number of Kupffer cells, which characterize liver damage. Transmission electron microscopy revealed an elongated and angular shape of the mitochondrion in the liver cell, with an abundance of peroxisomes, symptomatic of metabolic acidosis.

A blend of herbal essential oils enhanced the growth performance, blood bio-immunology traits, and intestinal health of Nile tilapia (Oreochromis niloticus)

Nile tilapia fed four levels (0, 0.25, 0.5, and 1 ml/kg) of a liquid blend of herbal essential oils (EOs) contains carvacrol, oregano, 1,8 cineol, thymol, pinene, pinene β, limonene, and propylene glycol for 60 days. The results showed higher final weight, weight gain, and specific growth rate (P<0.05) in fish delivered 0.25 and 0.5 ml EOs/kg than the control. However, the feed conversion ratio was markedly reduced in fish fed 0.5 and 1 ml EOs/kg (P<0.05). Lipase showed enhanced activity in fish subjected to a blend of EOs, while fish fed 0.5 ml/kg of EOs blend had higher amylase activity (P<0.05) than the other levels. Lysozyme activity and superoxide dismutase showed a higher value in fish received 0.5 ml EOs/kg. Additionally, phagocytic and catalase activities enhanced in fish received 0.5 and 1 ml/kg while phagocytic index enhanced in fish fed 1 ml/kg (P<0.05). Interestingly, the total immunoglobulin level was markedly higher, while malondialdehyde was lower in EOs-subjected fish (P<0.05) than in control. The histomorphology appearance of the intestine, liver, and spleen were enriched in EOs-treated fish comparing the control fish. In conclusion, the growth performance, feed efficiency, and blood bio-immunological indices of fish fed 0.5–1 ml of EOs blend per kg had the best performances.