Does Dietary Sodium Alginate with Low Molecular Weight Affect Growth, Antioxidant System, and Haemolymph Parameters and Alleviate Cadmium Stress in Whiteleg Shrimp (Litopenaeus vannamei)?

Decreasing low molecular weight can improve the digestibility and availability of ingredients such as sodium alginate. This study aimed to test the four dosages of low molecular weight sodium alginate (LMWSA) (0%: Control, 0.05%: 0.5 LMWSA, 0.10%: 1.0 LMWSA, and 0.2%: 2.0 LMWSA) in whiteleg shrimp (Litopenaeus vannamei) (3.88 ± 0.25 g) for eight weeks. After finishing the trial, shrimp were exposed to cadmium (1 mg/L) for 48 h. While feed conversion ratio (FCR) improved in shrimp fed dietary 2.0 LMWSA (p < 0.05), there was no significant difference in growth among treatments. The results showed a linear relation between LMWSA level and FCR, and glutathione S-transferase (GST) before; and malondialdehyde (MDA), glutathione (GSH), GST, and alanine transaminase (ALT) after cadmium stress (p < 0.05). The GST, MDA, ALT, and aspartate transaminase (AST) contents were changed after stress but not the 2.0 LMWSA group. The survival rate after stress in 1.0 LMWSA (85.23%) and 2.0 LMWSA (80.20%) treatments was significantly higher than the Control (62.05%). The survival rate after stress negatively correlated with GST and ALT, introducing them as potential biomarkers for cadmium exposure in whiteleg shrimp. Accordingly, the 2.0 LMWSA treatment had the best performance in the abovementioned parameters. As the linear relation was observed, supplementing more levels of LMWSA to reach a plateau is recommended.

The Combined Effects of Propionic Acid and a Mixture of Bacillus spp. Probiotic in a Plant Protein-Rich Diet on Growth, Digestive Enzyme Activities, Antioxidant Capacity, and Immune-Related Genes mRNA Transcript Abundance in Lates calcarifer Fry.

A 7-week feeding trial was conducted to evaluate the combined effects of propionic acid (PA, 5 or 10 g/kg) and a multi-strain Bacillus spp. (Bacillus subtilis IS02 (accession no. JN856456) and B. licheniformis IBRC-M 11,319) (1.7 × 107 CFU/g) probiotic in a plant protein source (PP)-rich diet (∼70% of dietary protein derived from PP sources) on performance of Asian sea bass (Lates calcarifer) fry (initial body weight 2.97 ± 0.11 g). In this regard, six isoproteic (∼48%) diets were formulated as follows: a control (without supplementation of the additives); probiotic (only contained Bacillus spp. mixture); 5 g PA/kg diet; 10 g PA/kg diet; probiotic + 5 g PA/kg diet, and probiotic + 10 g PA/kg diet. Specific growth rate in fish fed with 10 g PA/kg (2.84 ± 0.1%) and diets contained blends of probiotic and PA (2.76 ± 0.19% in probiotic + 5 g PA, and 2.79 ± 0.04% in probiotic + 10 g PA) was better than in the control (2.45 ± 0.1%) (P < 0.05). Feed conversion ratio in fish fed with 10 g PA/kg (0.92 ± 0.12) and diets contained blends of probiotic and PA (0.94 ± 0.06 in probiotic + 5 g PA and 0.91 ± 0.02 in probiotic + 10 g PA) was better than in the control (1.24 ± 0.08) (P < 0.05). Digestive enzymes including α-amylase, total alkaline proteases, and bile salt dependent lipase activities improved in fish fed diets contained additives. The activity of glutathione-S-transferase and glutathione reductase enhanced in the liver of fish fed diets contained additives. The relative abundance of lysozyme, interleukin 1ß, and insulin-like growth factor-1 genes mRNA transcript showed multifold increase in the liver of fish fed with the 10 g PA/kg and diets contained blends of probiotic and PA (P < 0.05). By considering the above mentioned results, supplementing a PP-rich diet with 10 g PA/kg diet or combination of PA and a mixture of Bacillus spp. probiotic recommended for L. calcarifer.

Salinity modulates biochemical and histopathological changes caused by silver nanoparticles in juvenile Persian sturgeon (Acipenser persicus).

The objective of this study was to evaluate the effect of salinity on the acute and sub-chronic toxicity of silver nanoparticles (AgNPs) in Persian sturgeon. This was evaluated by exposing Persian sturgeon to AgNPs in three salinities: freshwater (F: 0.4 ppt), brackish water 1 (B1: 6 ± 0.2 ppt), and brackish water 2 (B2: 12 ± 0.3 ppt) for 14 days, which was followed by analysis of alterations in plasma chemistry and histopathology of the gills, liver, and intestine. Values of 96-h median lethal concentration (LC50) were calculated as 0.89 mg/L in F, 2.07 mg/L in B1, and 1.59 mg/L in B2. After sub-chronic exposures, plasma cortisol, glucose, potassium, and sodium levels illustrated no significant changes within each salinity level. In F, 0.2 mg/L AgNP caused the highest levels of alkaline phosphatase and osmolality levels. In B1, 0.6 mg/L AgNP induced the highest level of alkaline phosphatase and elevated plasma osmolality was recorded in all AgNP-exposed treatments in comparison with the controls. The B2 treatment combined with 0.6 mg/L AgNP significantly reduced plasma chloride level. The results showed elevating salinity significantly increased osmolality, chloride, sodium, and potassium levels of plasma in the fish exposed to AgNPs. The abundance of the tissue lesions was AgNP concentration-dependent, where the highest number of damages was observed in the gills, followed by liver and intestine, respectively. The histopathological study also confirmed alterations such as degeneration of lamella, lifting of lamellar epithelium, hepatic vacuolation, pyknotic nuclei, and cellular infiltration of the lamina propria elicited by AgNPs in the gills, liver, and intestine of Persian sturgeon. In conclusion, the stability of AgNPs in aquatic environments can be regulated by changing the salinity, noting that AgNPs are more stable in low salinity waters.

Effects of dietary supplementation of bovine lactoferrin on antioxidant status, immune response and disease resistance of yellowfin sea bream (Acanthopagrus latus) against Vibrio harveyi.

This study investigated the effect of the dietary supplementation of bovine lactoferrin (LF) on growth performance, hematological and immunological parameters, antioxidant enzymes activity and disease resistance against Vibrio harveyi in yellowfin sea bream (Acanthopagrus latus) fingerling. The fish with initial body weight 10 ±â€¯0.3 g were randomly distributed at 10 fish per each 250 L fiberglass tank, and fed with four experimental diets (a control basal diet and three supplemented diets with 400, 800 and 1200 mg LF kg-1 diet) for 8 weeks. The obtained results showed that fish fed with LF supplemented diets had significantly higher final body weight as compared to control diet (P < 0.05). There were no significant differences between LF-treatments and the control group in white blood cell counts, red blood cell counts, hemoglobin and hematocrit. Total protein and complement activity (ACH50) in the serum of yellowfin sea bream were enhanced with increasing the dietary LF supplementation level (P < 0.05). The mucus lysozyme activity in fish fed on 800 and 1200 mg LF kg-1 was significantly higher than those fed on 400 mg LF kg-1 and control fish (P < 0.05). None of the antioxidant enzymes (catalase, glutathione reductase, glutathione S-transferase) was affected by LF supplementation (P > 0.05). Fish fed with dietary LF had a significantly higher survival rate than those fed with the control diet after challenge with Vibrio harveyi (P < 0.05). These results revealed that diet supplementation in A. latus especially with 1200 mg LF kg-1 improve fish growth performance and immune parameters, as well as survival rate against Vibrio harveyi.

Oxidative Status and Digestive Histology of Barramundi Perch in Response to Different Tank Colors.

The oxidative status and intestinal and liver histology of Barramundi Perch Lates calcarifer juveniles were investigated in an experiment using different tank colors (black, red, blue, and white) over 6 weeks. It has been previously shown that background color can affect physiological processes in different species. The background colors did not cause significant differences in malondialdehyde, catalase, or glutathione S-transferase, whereas superoxide dismutase and glutathione peroxidase activities were significantly higher in fish that were kept in black tanks. Plasma cortisol of fish adapted to blue and white tanks was significantly lower than that of fish in black tanks. The liver total antioxidant capacity was highest for fish that were maintained in white and blue tanks. The results of histopathological evaluation revealed that tank colors did not have significant effects on intestinal mucosal and enterocyte dimensions. No specific alterations were found in the liver or intestine of fish relative to the tank background color during the experimental period. In conclusion, white and blue tanks resulted in improved oxidative status of Barramundi Perch juveniles.

Effect of freezing rate for cryopreservation of Persian sturgeon (Acipenser persicus) spermatozoa.

This study examined the effect of freezing rate (-10 °C, -15 °C, -20 °C, -30 °C, and -40 °C/min) on motility parameters, rates of fertilization and hatching, ATP content, and indices of oxidative stress including thiobarbituric acid reactive substances and carbonyl derivatives of proteins in Persian sturgeon (Acipenser persicus) sperm. After sampling, sperm was diluted in an extender composed of 23.4-mM sucrose, 0.25-mM KCl, and 30-mM Tris-HCl, pH 8.0, containing 10% methanol and subsequently frozen in a programmable freezer. For postthaw sperm that were frozen at a rate of -40 °C/min, sperm motile duration (134 ± 27.01 seconds), sperm motile percent (60 ± 4.1%), fertilizability (72 ± 8.36% for fertilization rate and 65 ± 7.58% for hatching rate), and ATP content (4.8 ± 0.57 nmol/10(8) sperm) were significantly higher than for sperm frozen at any of the four slower rates (P < 0.05). Moreover, sperm cryopreserved using the fastest freezing rate had significantly lower levels of thiobarbituric acid reactive substances (0.5 ± 0.05 nmol/10(8) sperm) and carbonyl derivatives of proteins (41.3 ± 4.9 nmol/10(8) sperm) than sperm cryopreserved using all other freezing rates (P < 0.05). In addition, there is a significant difference (P < 0.05) between fresh sperm and the recovery of cryopreserved Persian sturgeon sperm using programmable freezing with -40 °C/min being the optimal freezing rate among those tested.