Alternative protein sources in diets for Japanese flounder Paralichthys olivaceus (Temminck and Schlegel): II. Effects on nutrient digestibility and digestive enzyme activity

An 8‐week feeding trial was conducted to compare the effects of dietary protein sources on nutrient digestibility and digestive enzyme activity. Four experimental diets were formulated to contain one of the following as the sole protein source: fish meal (FM), fish protein concentrate (FPC), soy protein concentrate (SPC) and soy protein isolate (SPI). Each diet was randomly assigned to triplicate aquaria stocked with 25 Japanese flounder (Paralichthys olivaceus) each. The dry matter, crude protein and energy digestibility and individual amino acid availability of the SPC‐based diet were significantly lower than those of the other diets. The crude lipid digestibility of soy protein‐based diets was significantly lower than that of the FM‐based diet. The pepsin/protease activity was significantly higher in fish fed fish protein‐based diets compared with fish fed soy protein‐based diets. The lipase activity in fish fed the SPI‐based diet was the highest among the dietary treatments. These results indicate that P. olivaceus can effectively digest the protein from FPC and SPI (but not SPC) as well as FM. The low protein digestibility and amino acid availability of the SPC‐based diet may be related to the non‐protein compounds present in SPC, whereas the low‐lipid digestibility of soy protein‐based diets may contribute to the undigested soy protein fractions and/or the alcohol‐soluble components.     

Development of a practical soy‐based diet for California yellowtail,Seriola lalandi

Two feeding trials were conducted to initiate the development of a practical soy‐based diet for California yellowtail (YT), Seriola lalandi. The first trial evaluated fish meal (FM), FM + solvent‐extracted soybean meal (SBM) or FM + soy protein concentrate (SPC)‐based diets and a commercial reference diet (Skretting Marine Grower). Final weights (31.8–67.6 g), per cent gain (492.8–1059.9%) and feed conversion ratio (1.11–1.59) all followed a similar response in that fish offered the commercial diet performed significantly better than fish maintained on the other diets. The second trial was designed to evaluate the replacement of FM with increasing levels of soy protein. The basal diet contained 400 g kg^?1 FM and 240 g kg^?1 SBM. The FM was then reduced to 300 g kg^?1, 200 g kg^?1 and 150 g kg^?1 of the diet using SPC as the replacement protein. Final weight (41.2–64.1 g) and per cent gain (110.5–226.5%) followed similar trends with decreases in performance as the FM level was reduced. No gross signs of enteritis were noted, indicating that reduced performance was likely due to nutrient deficiencies or palatability problems rather than an allergic response. Results demonstrate that there is potential to develop reduced FM diets for this species using soy protein.     

Effects of soy protein ratio,lipid content and minimum level of krill meal in plant‐based diets over the growth and digestibility of the white shrimp,Litopenaeus vannamei

This study evaluated the effects of soy protein ratio, lipid content and the minimum dietary level of krill meal in plant‐based diets over the growth performance and digestibility of Litopenaeus vannamei. Nine plant‐based diets varied the soybean meal (SBM) and soy protein concentrate (SPC) inclusion ratio at 1 : 2.3, 1 : 1 and 2.5 : 1, and their dietary lipid content at 121.4 ± 9.4, 102.3 ± 1.2, and 79.9 ± 1.2 g kg^?1 (in a dry matter basis). An additional diet containing 120 g kg^?1 of fish meal (salmon by‐product) was used as a control. Krill meal was included at 0, 5, 10, 20 and 30 g kg^?1 in a new set of plant‐based diets. After 10 weeks in clear‐water tanks of 0.5 m³, no effect of SBM:SPC ratio and dietary lipid content was detected on shrimp survival. However, dietary lipid levels of 80 and 121 g kg^?1 combined with a high SPC to SBM resulted in the lowest final body weight and the poorest apparent crude protein digestibility, respectively. Krill meal increased feed intake at only 10 g kg^?1, while at 20 g kg^?1, it accelerated shrimp growth, increased yield and reduced food conversion ratio.     

Performance and immunological responses of rainbow trout (Oncorhynchus mykiss) fed bioprocessed plant‐based proteins

Marine‐derived fish meal (FM) is a traditional component of commercial aquaculture feeds for many farmed fish species. Modern bioprocessing technologies have been developed to produce high‐protein plant‐based ingredients for aquafeeds to further reduce FM and other conventional animal protein sources. A 90‐day feeding trial using juvenile rainbow trout (Oncorhynchus mykiss) (27.9 ± 1.4 g; mean ± SE) was completed to evaluate growth, feed efficiency, general health and immunological responses to diets containing experimental plant‐based protein sources and reduced FM. Trout were fed one of four dietary treatments: experimental bioprocessed soy protein concentrate (BSPC), commercially available enzymatically hydrolysed soy protein concentrate (CSPC), experimental bioprocessed barley protein concentrate (BBPC) and a FM control (FMC). At trial termination, there were no significant differences in relative growth (RG) or specific growth rate (SGR) between fish fed either FMC or BSPC (p > .05). Fish fed either CSPC or BBPC resulted in significantly lower RG and SGR than the FMC (p < .05). Significant respiratory burst analysis differences were observed among treatments at day 90 (p < .01), for fish fed either FMC or CSPC diets. This assessment of bioprocessed plant‐based protein ingredients facilitates the characterization and incorporation of bioprocessed soy and barley protein as the industry continues to evaluate FM replacements in rainbow trout feeds.     

基于电子鼻技术的鱼露与鱼酿酱油的品质分析

通过电子鼻获取鱼露、鱼酿酱油和生抽的气味信息,进行主成分分析(PCA)、线性判别分析(LDA)和负荷加载分析(Loadings),并结合氨基酸态氮、盐分、全氮和游离氨基酸含量,对比分析3种调味品的品质。结果显示,3种调味品中游离氨基酸种类丰富,鱼露中苏氨酸、甘氨酸、丙氨酸、甲硫氨酸、赖氨酸的含量明显高于鱼酿酱油和生抽;生抽和鱼酿酱油中鲜味氨基酸的含量明显高于鱼露,但生抽中必需氨基酸的含量远低于鱼酿酱油和鱼露;3种调味品挥发性成分复杂,电子鼻10个金属传感器能很好地区分3种调味品的挥发性气味,W5S、W1S、W2S号传感器比其他7个传感器有更高的响应值,其中W2S号传感器的响应值变化最显著。这说明电子鼻能较好地区分鱼露、鱼酿酱油和生抽,虽然3种调味品中第1、2主成分相同,但醇类、氮氧化合物类物质对第1、2主成分的贡献率不同。     

Effects of dietary fish oil and soya bean lecithin on gonad index,colour and biochemical composition of the purple sea urchin,Strongylocentrotus purpuratus (Stimpson 1857)

The effects of increasing soya bean lecithin (SL) levels (0%, 2% and 4% of diet dry matter, DM) at two fish oil (FO) levels (0% and 3% DM) on gonad index, colour and biochemical composition of Strongylocentrotus purpuratus were evaluated using a 3 × 2 factorial design with six iso‐nitrogenous formulated diets. All diets generated an increase in gonad index of more than 9%. Dietary FO had a positive effect on diet digestibility and accumulation of proteins in the gonad. Soy lecithin did not affect gonad composition, but improved its coloration, decreased gonad feed conversion ratio and increased gonad protein efficiency. There was a clear effect of diets on sea urchins gonad protein, ash and fatty acid content, in particular, decreasing the n‐3/n‐6 ratio associated with a decrease in 20:5n‐3 when SL levels increased. Nevertheless, 22:6n‐3 levels increased by week 12 in all treatments, and diets with SL increased the content of 20:4n‐6 in gonads. A decrease in bitter‐tasting amino acids such as histidine, cysteine, valine and methionine was observed in all treatments with a concomitant increase in isoleucine levels. We recommend using a diet containing 3% of FO and 2% of SL to increase food consumption, diet digestibility, improving marketable gonad colour and an increasing gonad n‐6 fatty acids and C22:6n‐3. In addition, the present study paves the way for future research in the use of FO and SL as an additive in diets for S. purpuratus towards the goal of increasing gonad size and nutritional quality.     

Effects of feeding a fish meal‐free soy protein concentrate‐based diet on the growth performance and nutrient utilization of red sea bream (Pagrus major)

Two groups of red sea bream (average body weight 85 g) were fed to satiation fish meal (FM) or FM‐free soy protein concentrate (SPC)‐based diet (FM‐sat and SPC groups respectively). A third group (FM‐pair) was fed the same amount of FM as of SPC fed to SPC‐sat group for 6 weeks. Growth rate of SPC group was significantly slower than of FM‐sat and FM‐pair groups (p < 0.05). Feed conversion ratios of FM‐sat and FM‐pair groups were similar and were better than that of SPC group (p < 0.05). Visceral fat somatic index of SPC group was significantly lower than of the other groups (p < 0.05), while that of the latter two groups were similar. Plasma triglyceride of FM‐sat and FM‐pair groups was similar and lower than the level of SPC group (p < 0.05). Trypsin activity in hepatopancreas of SPC group was significantly lower than that of other groups (p < 0.05). We suggest a low growth of SPC group was not simply related to low‐feed intake. Feeding of a FM‐free SPC‐based diet may reduce lipid accumulation and consequently lead to low‐growth performance, in red sea bream.     

Use of plant‐based protein concentrates as replacement for fishmeal in practical diets for the Pacific white shrimp (Litopenaeus vannamei) reared under high stocking density and low salinity conditions

Two feeding trials were conducted to investigate the effect of replacing fishmeal with a combination of soy and corn protein concentrate (1:1 ratio) on growth performance of the Pacific white shrimp (Litopenaeus vannamei). A basal diet containing 200 g/kg fishmeal was systematically reduced (200, 150, 100, 50 and 0 g/kg) with protein concentrate on an isonitrogenous basis. Additionally, two diets containing 0 or 50 g/kg fishmeal were supplemented with lysine and methionine to evaluate possible limitations in EAAs. Each diet was randomly fed to five replicate tanks (15 shrimp per 75 L aquaria) reared in an indoor clear water system (Trial 1), or four replicate circular tanks (100 shrimp per 800 L) reared in outdoor green water system (Trial 2). In trial 1, results indicated a slight decrease in shrimp performance as fishmeal was replaced at the highest levels. Meanwhile, the supplementation of lysine and methionine to the diets did not result in shifts in survival, growth or FCR. In trial 2, there were no significant differences in growth performance across the tested diets. This study demonstrated that plant‐based protein concentrates can be used to replace fishmeal in practical shrimp diet in clear and green water under high stocking density.     

空化射流条件下大豆分离蛋白糖基化产物乳液特性研究

为探究空化射流对大豆分离蛋白糖基化产物乳液特性的影响,以大豆分离蛋白、葡萄糖、葡聚糖为原料,通过空化射流处理辅助糖基化制备大豆分离蛋白-葡萄糖共价复合物乳液、大豆分离蛋白-葡聚糖共价复合物乳液,探究空化射流技术对大豆分离蛋白糖基化产物乳液的粒径、ζ-电位、微观结构、蛋白吸附率、乳析指数及抗氧化性的影响。结果表明：经过一定时间的空化射流处理后的糖基化产物乳液平均粒径显著降低、ζ-电位增大、微观结构液滴逐渐变得均匀,蛋白吸附率升高、乳析指数降低、还原力和DPPH自由基清除能力均升高,并在空化射流处理80 min时,乳液特性达到最佳,且相比大豆分离蛋白-葡萄糖共价复合物乳液,大豆分离蛋白-葡聚糖共价复合物呈现出更好的乳液特性;但随着空化射流处理时间的进一步增加,糖基化产物乳液的平均粒径升高、ζ-电位减小、微观结构开始出现聚集情况,蛋白吸附率呈降低趋势,乳析指数逐渐升高。适当时间下的空化射流辅助处理可以改善糖基化产物的乳液特性,提高乳液的储藏特性和抗氧化特性。     

两级泡沫分离废水中大豆蛋白的工艺

为了有效处理高浓度大豆蛋白废水,在研究初始pH值、表观气速和温度特别是在较高温度（60℃）对泡沫分离大豆蛋白废水效果影响的基础上,建立了可同时提高富集比和回收率的两级泡沫分离工艺。在60℃时,对大豆蛋白质量浓度为4.0 g/L的废水泡沫分离,富集比比常温时提高4倍多。两级泡沫分离工艺中,第一级分离在大豆蛋白质量浓度为4.0 g/L,初始pH值为7.0,表观气速0.133 cm/s,60℃下操作,富集比为7.71,残液作为第二级泡沫分离的进料;第二级分离先在20℃,表观气速0.133 cm/s下进行,待塔顶