흰다리새우(Litopenaeus vannamei) 사료 내 곤충의 이용성에 관한 연구

Abstract

Insects have recently become an attractive alternative protein and lipid source for the production of sustainable aquaculuter feeds. In addition to their high protein levels, insects also rich in lipids, minerals and vitamins that support growth of shrimp and fish. Insects have been found to possess antifungal and antibacterial properties. Compared to most protein sources, insects farmed under controlled conditions could be a more viable protein source than fish meal in aquaculture feeds. Insects are rich in essential amino acids making them highly desirable as an excellent protein source for aquaculture. Therefore, insects can be a promising protein source for the production of aquaculture feed. Several insect species used in fish feeds have also been reported to improve the immune response, antioxidant activity and disease resistance of aquatic animals. Nonetheless, very few studies have assessed the benefits of using insect meals as a protein source for shrimps. Therefore, this study was conducted to examine the potential use of the insects as protein and lipid sources for Pacific white shrimp (Litopenaeus vannamei) feed. Study in Chapter 1 was conducted to examine digestibility of insect meals for Pacific white shrimp and their utilization as fish meal substitutes. The tested insect meals were meal worm, silk worm, black soldier fly, rice grasshopper, two-spotted cricket, dynastid beetle and whiteꠓspotted flower chafer. Apparent digestibility coefficients of the tested insect meals were 83–89% for protein, 91–98% for lipid, 84–90% for energy, 77–81% for dry matter, 28–36% for chitin, 76–96% for amino acids and 89–93% for fatty acids. The amino acid availability of the insect meals was high in taurine (93–96%), arginine (91–95%) and lysine (90–95%). Availability of fatty acids were 89–93% for saturated fatty acids, 90–93% for monounsaturated fatty acids and 88–93% for polyunsaturated fatty acids. For a feeding trial, a control diet was formulated using 27% tuna byproduct meal as a fish meal source and seven other diets were prepared replacing 10% tuna byproduct meal in the control diet with each insect meal (10%). Triplicate groups of shrimp (0.17 g) were fed the diets for 65 days. The growth performance was significantly improved when the shrimp were fed black soldier fly or dynastid beetle included diet. Dietary supplementation of insect meals significantly improved non-specific immune responses and antioxidant enzyme activity in the shrimp. Study in the Chapter 2 was conducted to partially replace fish meal with black soldier fly (BSF) or mealworm (MW) larvae in diets for Pacific white shrimp. A tuna by-product meal (27%) was used as fish meal in a control (Con) diet, which was replaced with 20%, 40%, or 60% BSF or MW, respectively. The shrimp (0.09 g) were randomly stocked in 28 acrylic tanks and quadruplicate groups per dietary treatment were fed one of the diets six times daily. After 57 days of the feeding trial, growth and feed utilization were significantly higher in shrimp fed BSF40 and BSF60 diets than those in shrimp fed Con diet. Phenoloxidase, superoxide dismutase, glutathione peroxidase and gene expression of crustin were significantly higher in shrimp fed BSF or MW diet than those in shrimp fed Con diet. Study in Chapter 3 was conducted to determine the supplemental effects of two insect meals, MW and BSF, with high or low lipid levels in diets for Pacific white shrimp. Sardine and tuna by-product meals were used as the fish meal sources in a Con diet. The fish meals were replaced with MW, defatted MW (deMW), BSF or defatted BSF (deBSF), respectively. The shrimp (0.47 g) were stocked into 20 acryl tanks (215 L) and fed the diets six times a day. After 45 days of the feeding trial, the shrimp fed insect meals had significantly higher phenoloxidase and superoxide dismutase activities than the shrimp fed Con diet. The gene expressions of prophenoloxidase, crustin and penaeidine-3c in shrimp hepatopancrease were also higher in shrimp fed the insect diets, regardless of defatting than those in shirmp fed Con diet. The survival during a Vibrio parahaemolyticus challenge test was higher in shrimp fed the diets containing defatted insect meals than in shrimp fed Con diet. In Chapter 4, we investigated the effects of dietary fish oil replacement with mealworm oil (MO) or black solider fly oil (BO) for Pacific white shrimp. Cod liver oil was used as the fish oil source in a Con diet. The fish oil was replaced with MO or BO by 25, 50, 75 or 100%, respectively. The shrimp (0.89 g) were stocked into 36 acryl tanks (215 L) and fed the diets six times a day. After 58 days of the feeding trial, the shrimp fed both insect oils had relatively higher growth performance and feed utilization than the shrimp fed Con diet. Phenoloxidase, superoxide dismutase and glutathione peroxidase activities were increased by dietary insect oil supplementations. The survival during a Vibrio parahaemolyticus challenge test was higher in shrimp fed the diets containing both insect oils than in shrimp fed Con diet. In summary, we investigated (1) the nutrient profile, ingreidnet digestibility and growth performance of domestic insec meals, (2) the opmtimum fish meal replacement level with black soldier fly and mealworm, (3) the effects of dietrary supplementation of insect meal as a feed additive and (4) the dietary utilization of insect oils as a lipid source. We suggested that insects can be used as a promising ingredient for shrimp feed.