AQUATIC PHYSIOLOGY AND BIOTECHNOLOGY
Year:2017 | Volume:5 | Issue:2|Papers Count:5

The objective of this study was to evaluate the effect of dietary supplementation with apple cider vinegar on the hemolymph parameters and Vibrio spp. colony forming unit (CFU) in the intestine of the Litopenaeus vannamei. In this study, two hundred twenty-fiveL. vannamei with an average initial weight of 10.2±0.04g were fed diets supplemented with of apple cider vinegar for 60 days. Treatments included levels of 0% (control), 2% and 4% apple cider vinegar diets (triplicate). The shrimps were randomly sampled for determination biochemical parameters hemolymph and Vibrio spp. counts at the end of the experiment. The results indicated that Vibrio spp. CFU counts of the shrimp fed with apple cider vinegar diets were significantly lower compared to the control group (P<0.05). The shrimps fed with the supplemental diets had significantly higher total protein and calcium levels (P<0.05). But, no significant difference was observed in the glucose level among treatments (P>0.05). In contrast, the cholesterol and triglyceride concentrations were significantly decreased in the shrimps fed with diets containing apple cider vinegar and a dramatic decrease was observed in 4% apple cider vinegar treatment (P<0.05). Results of this study indicated that the addition of apple cider vinegar can changes the hemolymph parameters and decreases Vibrio spp. CFU load in the intestine of shrimp.

Chlorpyrifos is one of the strong organophosphate pesticides that use very much and lead poisoning, disruptor in immune and physiology systems and live activities of aquatic organisms. Therefore, its effects can use as the biological indicator in a determination of pollutants. In this study, the effect of different concentrations of Chlorpyrifos (5, 10, 20, 30 and 40 mg/L) were investigated on thyroid hormones of grass carp (Ctenopharyngodon idellus) during 14 days. Blood sampling performed in 12, 24 and 96h and also 7 and 14 days after the exposure. The concentrations of serum thyroid hormone were determined using Radioimmunoassay method. Results showed the significant decrement in the serum T3 and increment of the serum T4 in the treated fishes in comparison to the control groups. In addition, the decrement in ratio T3/T4 was observed (P<0.05). In conclusion, the Chlorpyrifos is classified as an intense toxic pesticide for the grass carp that have high effects on the fish thyroid hormones equilibrium, metabolism activity, and growth.

Fish embryo cryopreservation means substantiation of the body water with a cryoprotectant. Knowledge of cryoprotectants toxicity is one of the prerequisites for the design of embryo cryopreservation protocols. In the present study common carps (Cyprinus carpio) in two stages of embryonic development, half-epiboly (8 h post-fertilization) and heartbeat (32 h post-fertilization) stage, were exposed to pronase, type XIV of Streptomyces griseus, for 5 min. Permeabilized embryos were immersed in various cryoprotectants including glycerol, ethylene glycol and acetamide in concentrations of 1, 2, 3 and 4M for a period of 5 and 15min. Embryos were then washed and incubated until hatched. The toxicity of the cryoprotectant was assessed by the hatching rate. The results indicated that glycerol had less toxicity compared to ethylene glycol and acetamide. Moreover, embryos could tolerate glycerol in high concentrations. Acetamide was found to be the most toxic cryoprotectant. Reduced hatching rate may be a result of osmotic shock, ionic imbalance or consequence of cryoprotectant toxicity. As concentrations were increased, hatching rate decreased. Similarly, hatching rates of embryos were decreased as the exposure time increased (5 to 15 min). With the increasing of the embryonic development sensitivity to cryoprotectant were decreased. Results suggest that glycerol and ethylene glycol would be good options for cryopreservation of common carp embryos at heartbeat stage.

The aim of this research is the study of the freezing effects at -20°C after hydration and dehydration on the hatching efficiency, survival percentage and growth of Artemia urmiana cysts. Experiments were carried out in four treatments. In the first treatment, hatching was done after one hydration and dehydration cycle with the standard method. In the second treatment, hatching was done after one hydration and dehydration cycle and then one week freezing at -20°C temperature. In third treatment, hatching was done after one hydration and dehydration cycle and then one month freezing at -20°C temperature. Standard hatching was done without any other treatment in the control group (fourth treatment). Results indicated the cyst hatching percentage increased by increasing freezing time (one-month freezing), even though hatching percentage was higher in control group. The most survival percentage was observed in the 11th day of third treatment. The highest growth was in 15 to the 25th day of third treatment (P<0.05). To sum up, freezing is not necessary for Artemia urmiana and performing it decreases hatching percentage.

Successful reproduction is one of the most important issues in aquaculture. In this regard, gamete quality is a limiting factor. Selenium, improves the reproduction and immunity in all animals. In the present study, the effects of diets containing different level of Nano-Se on growth indices, gonad histology and activity of two seminal plasma antioxidants, malondialdehyde (MDA) and glutathione peroxidase (GPx), were assessed. Male goldfish (67.28±0.74g, n=200) were fed with 0 (control), 0.1, 0.5 and 1 mg of Nano-Se per Kg of a commercial food for 8 weeks. The developmental stages of the gonadal were evaluated using a common histological method. HCG hormone injection was done to artificially obtain the sperm. The higher Nano-Se concentrations increased and decreased the growth and FCR, respectively. The activity of GPx and MDA in seminal plasma increased in the fishes fed the diets containing Nano-Se, and also the histological observations of the gonads illustrated an increase in spermatozoa count. Hence, 0.5 and 1 mg/Kg Nano-Se improve the growth and gonad indices, and increase the activity of the antioxidant seminal plasma enzymes in goldfish.