نوع مقاله : مقاله پژوهشی
نویسندگان
گروه شیلات، دانشکده علوم دامی و شیلات، دانشگاه علوم کشاورزی و منابع طبیعی ساری، ساری، مازندران
چکیده
کلیدواژهها
موضوعات
عنوان مقاله [English]
نویسندگان [English]
Introduction: Aquaculture is the fastest-growing source of animal protein globally and currently provides nearly half of the world's seafood consumption. Due to the limited fishery resources from ocean catches, this shortfall must be addressed through the aquaculture industry. To tackle the issues of fishmeal shortages in recent decades, special attention has been given to the use of alternatives such as insects in aquaculture feed. Insects are one of the most diverse animal groups in the world, with some species possessing suitable nutritional value. Among insects, the yellow mealworm Tenebrio molitor stands out due to its high protein and fat contents. It also contains considerable amounts of bioactive compounds and chitin with antioxidant potential, antibacterial peptides, and other immune stimulants that enhance immunity and improves hematological parameters in various aquatic species. In this study, the effects of replacing fishmeal with the yellow mealworm larvae meal were investigated on blood parameters, serum biochemical composition, and liver enzymes in Beluga, Huso huso.
Materials and methods: A total of 360 fish with an average weight of approximate 112.9 ± 8.0 g were randomly distributed to polyethylene circular tanks with a capacity of 1500 liters. The experimental treatments (each with three replicates) included the replacement of 0% (control), 20%, 40%, 60%, 80%, and 100% of yellow larval mealworm (MW) meal with fish meal. At the end of the trial, blood sampling was performed using a syringe from the fish's caudal fin. The counting of red blood cells and white blood cells was done using a hemocytometer (Neubauer), and the hematocrit was measured through the microhematocrit method, while the hemoglobin concentration was measured by the cyanmethemoglobin method using a spectrophotometer at a wavelength of 540 nm in grams per deciliter. Liver enzyme levels including alkaline phosphatase (ALP), aspartate aminotransferase (AST), and alanine aminotransferase (ALT) were measured using the α-ketoglutarate method. Lactate dehydrogenase (LDH) was tested using the lactate-pyruvate method to determine the possibility of tissue damage. Data analysis was performed using One-Way ANOVA and Duncan's multiple range comparison tests were performed at a significance level of P<0.05.
Results: According to the results of growth indices, the highest body weight gain and specific growth rate were achieved in treatments substituted with 40% and 60% MW (P<0.05). The survival rate of the fish did not show a significant difference between the treatments (P>0.05). The number of white blood cells, red blood cells, hemoglobin, and hematocrit decreased as mealworm powder increased in diet, with the lowest values observed in 100% MW (P>0.05). The values of MCH and MCHC significantly decreased with 100% MW replacement (P>0.05). Lymphocyte numbers were significantly higher in 40% and 60% MW groups compared to the 20% (P>0.05). The values of albumin and total protein improved with dietary replacement of MW powder, except for the 100% replacement (P<0.05). The concentration of triglycerides in group with 20% MW was similar to that of the control (P<0.05); however, it decreased as the MW replacement increased (P<0.05). Hepatic enzymes such as AST, ALT, and ALP decreased with the inclusion of MW in the diet (P<0.05).
Discussion: Total protein and albumin play an important role in immune responses, and the improvement of these parameters in the current study may indicate enhanced immunity in beluga after replacing fishmeal with MW. Additionally, diets containing insect meal improve the microbial composition of the digestive system, ultimately affecting fish immunity and health. Chitin also regulates fat metabolism by preventing the hepatic circulation of bile acids and interfering with the natural digestion and absorption of fats in the intestine and the biosynthesis of fatty acids in the liver.
Conclusion: Based on the results, it is not feasible to completely replace MW meal with fishmeal, and a 20% replacement level is suggested as the optimal for beluga. However, substitution levels up to 40-60% may also be considered with caution.
کلیدواژهها [English]