No abstract

Micro-algae, Schizochytrium sp., is rich source of docosahexaenoic acid, DHA (66%-lipid with 27%-DHA). Eight nutritionally balanced-diets were formulated: diet 1 (control) consisted of only fish oil (FO); diets 2 and 3 had increasing amounts of algae-meal and soybean oil (SBO) at the expense of FO; diet 4 consisted of a combination of algae meal (37-g/kg), SBO (21-g/kg), and linseed oil (LSO) at 4-g/kg each; diet 5 had microalgae meal at 50-g/kg and equal amounts of LSO and SBO at 8-g/kg; diets 6 and 7 contained equal amounts of algae-meal at 62-g/kg, but with LSO or SBO added at 8-mg/g, respectively; diet 8 contained only algae-meal at 75-mg/g. Growth and feeding efficiencies of L. vannamei were not significantly different among treatments. Fatty acid composition of muscle generally reflected that of the diet. The amount of muscle sub-epidermal adipose tissue was significantly higher for shrimp fed diets 3 and 7, while intestinal lipase was significantly higher in shrimp fed diets 7 and 8. Muscle lipid peroxidation was unaffected by the dietary treatments, although antioxidant activities were significantly higher in shrimp fed diet 7 compared to those fed diet 1. Overall algal-meal can completely replace the FO in shrimp feed.

A 12‐week experiment was conducted to evaluate replacing fish oil (FO) in Pacific white shrimp (Litopenaeus vannamei) diets with algal meal (Schizochytrium sp. [AM]) and vegetable oils (VO: linseed oil [L] and soybean oil [S]). For this purpose, 15 aquaria (110‐L each) were arranged in an indoor rack recirculating saltwater system (salinity, 27–28 ppt) and a 2,000‐L mechanical and biological propeller‐washed bead filtration system. Juvenile shrimp (initial weight, 3.15 ± 0.01 g) were randomized into five groups of three replicates and fed one of five iso‐nitrogenous (400 g/kg crude protein) and iso‐lipidic (100 g/kg lipid) diets such as control (50 g/kg FO), FO‐AM0 (80 g/kg FO), FS‐AM1 (40 g/kg FO + 20 g/kg VO + 28.8 g/kg AM), FLS‐AM2 (20 g/kg FO + 20 g/kg VO + 58.7 g/kg AM) and LS‐AM3 (0 FO + 20 g/kg VO + 88.5 g/kg AM). No differences were found in most production performance parameters, except final body weight, which was significantly (p < 0.05) lower in the group fed diet LS‐AM3 (complete replacement of fish oil) compared with those fed diets FO‐AM0 and FLS‐AM2. Proximate and fatty acids composition were altered by the supplementation of AM and VO. Muscle and hepatopancreatic linoleic acid, linolenic acid and docosahexaenoic acid levels increased with increasing dietary AM, while eicosapentaenoic acid levels decreased. AM and VO supplementation significantly influenced the major total fatty acids in the tail muscle (MUFA, n‐6 PUFA, n‐3 PUFA and LC‐PUFA) and hepatopancreas (SFA, MUFA, LC‐PUFA and ratio of n‐3/n‐6), with higher n‐6, n‐3 and LC‐PUFAs and ratios of n‐3/n‐6 in high AM diets (LS‐AM3 and FLS‐AM2). Lipase activity increased with increasing dietary AM, whereas adipocytes decreased (p < 0.05). Significantly lower total cholesterol was measured in groups fed control and FLS‐AM2 diets compared to those fed FO‐AM0 and LS‐AM3. Algal meal could replace FO up to 75% and play an important role as a source of essential fatty acids in shrimp diets without compromising growth and health.

No abstract

A 12‐week growth trial was conducted to assess an improved soybean meal (ISBM) in the diet of Pacific white shrimp (PWS). Four isonitrogenous and isolipidic experimental diets were formulated: the control diet (ISBM‐0) contained 30% fishmeal (FM) and three test diets (ISBM‐33, ISBM‐66 and ISBM‐100) were formulated by gradually replacing FM on an isonitrogenous basis. Groups of PWS (3.2 g mean initial weight) were fed their respective experimental diets three times per day. Production performance of PWS was unaffected by diet, except the final weight of shrimp‐fed ISBM‐66 diet was significantly lower than those fed ISBM‐0. Whole‐body moisture was significantly higher and protein was significantly lower in PWS‐fed ISBM‐100 versus shrimp‐fed ISBM‐0. PWS‐fed ISBM‐66 had significantly higher oleic acid than shrimp‐fed ISBM‐0 and linolenic acid versus shrimp‐fed ISBM‐0 and ISBM‐100. The lowest linoleic acid and n‐6 polyunsaturated fatty acids levels were found in shrimp‐fed ISBM‐100. Based on second‐degree polynomial regression analysis of final weight and weight gain, the estimated optimum levels of ISBM to replace FM in PWS diets are 89.13% and 95.56% respectively. Overall, results indicate alternative, sustainable, plant‐based protein sources such as ISBM may potentially replace FM in PWS diets.