Evaluation of sacha inchi meal as a novel alternative plant protein ingredient for red hybrid tilapia (Oreochromis niloticus×O. mossambicus): Growth performance, feed utilization, blood biochemistry, and histological changes

Effect of Vietnamese coriander Powder on Growth, Body Composition, Hematology, and Immune-Related Gene Expression in Nile Tilapia

Dietary supplementation of plant herbs into aquafeed is recommended for intensive and sustainable aquaculture practices. This study has investigated the effect of Persicaria odorata (PO) leaf powder on growth, feed utilization, whole-body composition, hematology, and immune-related gene expression in Nile tilapia (Oreochromis niloticus). Fish (∼7.77 ± 0.01 g/fish) were randomly allocated into four treatment groups, each with three replicates. They were fed with dietary supplementation of PO at concentrations of 0, 15, 30, and 50 g/kg (termed PO0-PO50) for 10 weeks. Results indicated that the final body weight, weight gain, and specific growth rate were significantly higher at all PO supplementation levels compared to the control, with the highest value in the PO30 group. Similarly, the protein efficiency ratio and protein productive value in all PO groups were significantly higher than those of the control group. Red blood cells, white blood cells, and hemoglobin levels showed quadratic increases in the PO groups. In addition, total protein, globulin, and high-density lipoprotein cholesterol were linearly and quadratically increased with increasing PO levels, but alanine aminotransferase activity was linearly and quadratically decreased. Furthermore, dietary PO supplementation linearly decreased triglyceride and lipoprotein cholesterol levels, with the lowest levels found in the PO15 group. The expression of genes related to immunity showed that dietary supplementation of PO significantly increased the expression of proinflammatory factors (IL-1β and TNF-α), anti-inflammatory (IL-10 and TGF-β), and HSP70. In addition, glucose and cortisol levels decreased in all PO-supplemented groups, with the lowest levels found in the PO50 and PO30 groups, respectively. These findings showed that a dietary intervention with PO could improve growth, feed utilization, hematological parameters, upregulating genes related to immunity, and decreasing stress markers in Nile tilapia. Consequently, the utilization of PO at a dosage of 30 g/kg could contribute to the sustainable development of the aquaculture sector.

Impacts of dietary α-tocopherol acetate on physiological response, antioxidant activity, innate immunity, and histopathological status of Nile tilapia, Oreochromis niloticus under heat and salinity stress

Aquaculture fish face stresses include temperature, ammonia levels, water salinity, and dissolved oxygen. In order to sustain finfish output, it is necessary to assess the impact of unexpected weather on their performance. Thus, this study examined whether Nile tilapia's vitamin E intake reduces heat and salinity stress. After 56 days of feeding a diet enriched with vitamin E at 0, 150, 300, 600, and 1200 mg/kg, Nile tilapia were split into two groups: one was given a 28 g/L salinity increase, and the other to a temperature increase of 36 °C. Heat and salinity stress increased cortisol, glycose AST, ALT, triglycerides, and total cholesterol while decreasing albumin, globulin, and protein. Fish diets with vitamin E significantly improved the parameters above before and after heat and salinity stress. However, heat and salinity stress inhibited superoxide dismutase, catalase, glutathione peroxidase, nitrous oxide, lysozyme, phagocytosis, and immunoglobulin, reducing antioxidant activity and immunological responses. The Nile tilapia diet's vitamin E content increased antioxidant activity and immunological response before and after stress. Heat and salinity stress increased lipid peroxidation (malondialdehyde), but vitamin E-fed fish had lower values than controls. In addition to mild hepatocyte degeneration, pyknosis, and hepatic central vein congestion, heat and salinity stress cause severe vascular congestion with gill lamellar epithelium degeneration, sloughing, and primary filament congestion. In Vit E-treated groups, histomorphology returned to normal. Results showed that vitamin E at 1200 mg/kg in the Nile tilapia diet may be an effective antioxidant immunostimulant against environmental stressors like heat and salinity.

A preliminary study on the effects of substituting fishmeal with defatted black soldier fly (Hermetia illucens) larval meal on Asian seabass (Lates calcarifer) juveniles: Growth performance, feed efficiency, nutrient composition, disease resistance, and economic returns

This study aims to develop an alternative aquafeed derived from insect meal for Lates calcarifer juveniles, with the objectives of exploring the physiological performance, biological parameters, and economic analysis of substituting fishmeal (FM) with defatted black soldier fly (Hermetia illucens) larvae (BSFL) as part of the diet of L. calcarifer juveniles. Five practical diets were formulated to include 0% (BSFL0, serves as control group), 5% (BSFL5), 10% (BSFL10), 15% (BSFL15), and 20% (BSFL20) of BSFL meal, partially or fully replacing FM, respectively. Each diet was randomly assigned to triplicate groups of 30 fish (10.70 ± 0.07 g) per tank (300 L). The fish were fed twice daily to apparent satiation. A 56-day feeding trial was conducted to evaluate the impacts of defatted BSFL meal replacing FM on the growth performance, feed efficiency, composition analysis of fish muscle, cumulative mortality rate challenged with Vibrio parahaemolyticus, and economic returns of L. calcarifer. These results show that differences in weight gain and specific growth rate among the different treatments were statistically significant (p < 0.05), except for the absence of significant variation (p < 0.05) between BSFL0 and BSFL5, and followed by BSFL10 > BSFL0 > BSFL5 > BSFL15 > BSFL20. However, the feed conversion ratio and protein efficiency ratio showed the opposite trend as above. Although the diets experienced a decline in crude protein content and an increase in crude fat content with the increasing proportion of BSFL substituting FM, the crude protein and fat content of fish muscle were only slightly influenced. It is worth mentioning that levels of nonessential amino acids, delicious amino acids, saturated fatty acids, omega-6, omega-9 in BSFL10 group all showed an increase compared with the control group. After a 7-day challenge test with V. parahaemolyticus, the cumulative mortality rates of the BSFL5 and BSFL10 groups, respectively, dropped to 5.20%, 5.28% compared to the control group's 16.88%; however, the mortality rates of BSFL15 (34.67%) and BSFL20 (41.77%) groups were found to be significantly (p < 0.05) increased. From an economic perspective, the incidence cost for each experimental group showed a trend as BSFL10 < BSFL0 < BSFL5 < BSFL15 < BSFL20, whereas the profit index in each treatment exhibited the opposite trend as above. It was concluded that low (5%) or moderate (10%) levels of BSFL substituting FM in aquaculture feed could improve the physiological performances, disease resistance, and economic returns of L. calcarifer. However, excessive substitution (>15%) leads to a negative effect. From an economic point of view, 10% inclusion of BSFL in practical diets is recommended for L. calcarifer juveniles.

Effects of thermal stress responses in goldfish (Carassius auratus): growth performance, total carotenoids and coloration, hematology, liver histology, and critical thermal maximum

The present study aimed to investigate the effect of thermal stress on growth, feed utilization, coloration, hematology, liver histology, and critical thermal maximum (CTmax) in goldfish (Carassius auratus) cultured at three different acclimation temperatures including 27 °C, 30 °C, and 34 °C for 10 weeks. Goldfish were assigned randomly to tanks with a quadruplicate setup, accommodating 20 fish per tank. The result showed that fish acclimated to different temperatures did not significantly differ in weight gain (WG) and specific growth rate (SGR). However, increasing temperature significantly decreased feed efficiency ratio (FER), protein efficiency ratio (PER), and protein productive value (PPV), but significantly increased feed conversion ratio (FCR) (P < 0.05). The coloration parameters significantly decreased by high temperature in the trunk region with increasing temperature (L* and a* at week 5; L*, a*, and b* at week 10; P < 0.05). Total carotenoid contents in serum, fin, muscle, and skin also significantly decreased with increasing temperature (P < 0.05). Total protein, albumin, and globulin levels exhibited a notable decrease, while the albumin: globulin ratio showed a slight insignificant increase, with increasing temperature. Aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), total cholesterol, and triglycerides significantly increased with increasing temperature (P < 0.05). While, high-density lipoprotein cholesterol (HDL-c) decreased linearly (P < 0.05). Glucose and cortisol levels linearly increased with increasing temperature, the highest levels being observed in the 34 °C group. Liver histology showed swollen hepatocytes, nuclei displacement, and infiltration of inflammation in fish cultured at 34 °C. Goldfish acclimated to 34 °C displayed a higher CTmax of 43.83 °C compared to other groups. The present study showed that temperature should be kept below 34 °C for goldfish culture to prevent high FCR, fading coloration, and liver damages.

Comparison of immune defense and antioxidant capacity between broodstock and hybrid offspring of juvenile shrimp (Macrobrachium nipponense): Response to acute ammonia stress

Ammonia is a major environmental pollutant in the aquatic system that poses a great threat to the health of shrimp. Macrobrachium nipponense, as one of the large-yield farmed shrimp, is facing germplasm degradation. Genetic improvement through hybridization is one of the effective methods to solve this problem. However, there are few studies on the effects of ammonia nitrogen on the germplasm resources of M. nipponense. In this study, the broodstock populations (Dianshan, DS) and hybrid offspring (DS ♀ × CD [Changjiang, CJ ♂ × Dongting, DT ♀], SCD) were exposed to 0, 5, or 20 mg/L of ammonia for 96 h. The survival rate of the SCD group was greater than the DS group, although there were no significant differences in weight gain rate and length gain rate (p > 0.05). The number of positive cells and apoptosis rates in the DS group were significantly greater than in the SCD group after ammonia exposure (p < 0.05). As the ammonia concentration increased, the antioxidant enzyme activities in the SCD group were significantly higher than DS group, while the hepatotoxicity enzyme activities in the SCD group were significantly lower than DS group (p < 0.05). The trends in the expression of antioxidant- and immune-related genes were generally consistent with the activities of antioxidant enzymes. Our study found that the hybrid population had stronger stress resistance than their parent populations at the same ammonia concentration. This study confirms our speculation that hybrid population has a greater advantage in antioxidant immunity, which also provides reference for the follow-up study of chronic ammonia toxicity.