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Experiments to assess the effectiveness of the immunostimulator methisoprinol (Polfa Grodzisk Pharmaceuticals, Poland) focused on its impact on the innate immune response. The impact of different doses of methisoprinol on organ leukocytes isolated from the kidneys and spleens of African catfish that were subjected to or not subjected to the suppressive impact of iridovirus. The results indicate that the addition of methisoprinol causes increased respiratory burst activity (RBA), potential killing activity (PKA), and proliferative activity of lymphocytes T and B in response to mitogens. Methisoprinol stimulates the mechanisms of cellular immunity that are linked to the activation of T lymphocytes, which can impact the antiviral activity of this preparation after its application in vivo.
Probiotic organisms are used in fish culture to accelerate growth, improve the absorption of nutrients, enhance immune resistance, and reduce negative effects of stress. Probiotic microorganisms used in aquaculture include gram positive bacteria (Lactobacillus, Lactococcus, Enterococcus, Carnobacterium, Streptococcus, Bacillus), gram negative bacteria (Shewanella, Aeromonas, Vibrio, Enterobacter, Pseudomonas), fungi (Saccharomyces, Debaryomyces, Phaffia), and algae (Tetraselmis). Probiotics increase the expression of cytokines and affect the cellular and humoral defence mechanisms of the host by increasing the activity of phagocytic cells, complement, and lisozyme level. Probiotic bacteria in the intestines stimulate the immune system through the gut-associated lymphoid tissue (GALT). Probiotic bacteria can be used for protection against bacterial fish pathogens (Aeromonas salmonicida, Vibrio anguillarum, Vibrio ordalii, Yersinia ruckeri). Some publications also report anti-viral, anti-parasitic, and anti-fungal affect of probiotics. This study reviews the results of research on the efficiency of selected probiotics in various fish species. Probiotics may make it possible to achieve better results in fish culture without the need to use harmful and expensive chemotherapeutic products.
Shrimp farming is an economically important part of aquaculture. Shrimps constitute the largest portion of shellfish intended for human consumption. According to the World Organization for Animal Health (OIE), viral diseases pose the most serious threat to shrimp farming. There are currently six viral and two bacterial diseases on the OIE list. The most serious viral diseases are white spot disease (WSD), Taura syndrome (TS), infection with yellow head virus genotype 1 (YHV), infectious hypodermal and haematopoietic necrosis (IHHN), infectious myonecrosis (IMN) and white tail disease (WTD), whereas the most dangerous bacterial diseases are acute hepatopancreatic necrosis disease (AHPND) and necrotizing hepatopancreatitis (NHP). All these diseases result in high mortality, thus limiting shrimp production and causing large economic losses. Therefore, effective preparations are constantly sought to control infectious diseases in shrimps. Probiotics and immunostimulants, thanks to their demonstrated antibacterial and antiviral effects, as well their positive impact on the immune system, may play a crucial role in protecting the health of shrimps.
Nutritional support is important for optimum health in fish as it provides the building blocks of innate defense mechanisms and thus protection against infectious diseases. In the present study, we determined the influence of β-glucan (Leiber ®Beta-S) delivered with food on the nonspecific humoral defense mechanisms in fingerling carp. The fish weighed 15-17 g. Four tanks in a recirculation system were stocked with 100 fish each. The water temperature was 20-22°C. The fish were fed daily with commercial pellets containing β-glucan (Leiber ®Beta-S) at doses of 100, 200, and 400 mg per kg of pellets. The feed was prepared by the carp protocol used at the Inland Fisheries Institute. The control group was fed glucan-free pellets. On days 14 and 30 of the experiment, blood was drawn from 10 fish from each group and the nonspecific humoral defense mechanism parameters were examined. The results showed that β -glucan (Leiber ®Beta-S) at doses of 100, 200, and 400 mg per kg of pellets increased the myeloperoxidase activity in blood leukocytes and lysozyme activity in the serum. Total protein and immunoglobulin (Ig) levels were also increased in the serum. The optimal stimulating effect was observed following 30 days of application at a dose of 200 mg of β-glucan (Leiber ®Beta-S) on kg of pellets in fingerling carp.
In 2010 studies were continued that focused on determining the abundance, condition, and health of sea trout and salmon spawners caught in the Vistula and the Drwęca and other Pomeranian rivers. These results are compared with those of previous years, and the pathogenic factors that could have an impact on the occurrence of disease are determined. Substantial decreases in the numbers of fish ascending to spawn were confirmed in all of the rivers investigated. The number of individuals exhibiting disease symptoms also decreased. Pathogenic changes were observed in sea trout caught in four Pomeranian rivers: Reda, Parsęta, Wieprza, and Słupia, and also in one salmon specimen from the Rega River. No symptoms of disease were observed in sea trout or salmon from rivers in the eastern part of the coast (Łupawa, Łeba, Vistula, Drwęca). The bacteria isolated from fish in 2010 was more abundant than in 2009, but, as in the previous year, it was not possible to determine unequivocally the pathological factor. Mycological tests performed on samples taken from symptomatic body surfaces confirmed the occurrence of yeast from the genus Rhodotorula and fungus from the family Saprolegniaceae, which can be secondary pathogens.
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