[Effects of garlic essential oil as an immunostimulant on hematological indices of juvenile beluga [huso huso]]

Beluga [Huso huso] is one of the most valuable species of sturgeons and many efforts have been made to artificially reproduce, culture and restore this precious species. The objective of this study was to find the effects of garlic essential oil as an immunostimulant on hematological indices and on the cellular immunity system of juvenile belugas. An experiment was organized in which six different diets were fed to belugas including: diet without garlic essential oil and antibiotic, diet with oxytetracycline antibiotic [30 mg/kg], and four diets with various amounts of garlic essential oil [0.05, 0.10, 0.15 and 0.20 g/kg]. Beluga juveniles with an average weight of 24 +/- 2 g were fed these diets for 56 days. At the end of the experiment, hematological indices were determined. The blood coagulation time and mean corpuscular hemoglobin [MCH] indices increased in the groups treated with garlic essential oil. Significant increases in lymphocyte counts were observed in groups fed 0.05, 0.10 and 0.15 g/kg garlic essential oil as compared with the antibiotic and control groups. A significant decrease in the blood neutrophil count was observed in the belugas fed 0.15 and 0.20 g/kg garlic essential oil compared with the other treatments. In conclusion, these results showed that adding garlic essential oil increases the blood coagulation time, the hemoglobin content of red blood cells, lymphocyte numbers, and decreases eosinophils. Significant improvements of the immune system and of the physiological condition were observed in juvenile belugas receiving garlic essential oil compared with the control and the antibiotic treatments. It can therefore be used as a suitable replacement for oxytetracycline in the diet of juvenile belugas

[Effects of bacteriocine Z on the shelf-life of silver carp fillets during refrigerated storage]

Because of the high perishability of fish, keeping the quality of fresh fish is one of the most important problems in the fish-processing industry and for the consumers. The aim of this study was to determine the antibacterial and antioxidant effects of bacteriocine Z on silver carp fillets during refrigerated storage. After being weighed, fish fillets were sprayed with nisin Z [0.2 g/kg] packaged in vacuum and refrigerated [4°C]. Microbial [TVC, PTC, LAB] and chemical [PV, TBA, TVB-N] parameters were measured at days 0, 3, 6 and 9. As compared with the nisin Z-treated fish samples, the psycrotrophic, lactic-acid, and aerobic-mesophilic bacterial counts were higher in the control samples. The microbial parameters decreased significantly in the nisin Z-treated samples at the beginning of the period, followed by a slower rate of increase than the control; the chemical parameters showed a slower rate of decrease. Using metabolites as natural preservatives in fish fillets may increase shelf-life of silver carp fillets during refrigerated storage. Bacteriocine Z may extend their shelf-life at 4°C by 3 days