We evaluated the effects of fishmeal substitution with alfalfa protein concentrate on growth, body composition, and blood biochemistry in juvenile starry flounder. We formulated six isonitrogenous and isoener-getic diets, in which fishmeal protein was replaced by alfalfa protein concentrate in the following proportions: 0% (SO), 10% (S10), 20% (S20), 30% (S30), 40% (S40), 50% (S50). Specific growth rate (SGR), daily feed intake (DFI), feed efficiency (FE) and protein efficiency ratio (PER) were unchanged in fish fed SO, S10 or S20, but were significantly lower in fish fed S30, S40, or S50 (PO.05). The condition factor (CF) was lower and the digestive tract index (DTI) was higher in fish supplemented with alfalfa protein concentrate (P<0.05). The apparent digestibility of dry matter, protein, and lipid were all linearly decreased by the addition of alfalfa protein concentrate (P<0,05). Broken line analysis based on SGR revealed that the optimum replacement ratio was 19.0% in the diets of juvenile black sea bream, body weight (83.0±0.20) g. The levels of muscle lipid were significantly lower in fish fed S40 than those fed diets SO and S20 (P<0.05), while there was no obvious effect on the other proximate constituents (.P>0.05). Liver moisture increased significantly in fish fed diets SO, S10, and S20, and then leveled off in fish fed diets S30, S40, and S50. The reverse was true for liver lipid content. Crude protein was significantly higher in the liver of fish fed diets S30 and S50 than in fish fed SO. Liver crude ash content was not affected by fishmeal replacement. The whole fish moisture content was increased whereas crude lipid content was decreased by dietary fishmeal substitution with alfalfa protein concentrate (P<0.05). Whole fish crude protein content was highest in fish fed S30 and lowest in fish fed S40. There was no change in whole fish crude ash content (P>0.05). Triglycerides were significantly reduced by replacement of >20% fishmeal. Cholesterol content and lysozyme (LSZ) activity were both linearly decreased by alfalfa protein concentrate supplementation (P<0.05). Alkaline phosphate (ALP) activity was depressed by diets S20 to S50 (P<0.05). AST and ALT activities were enhanced by experimental diets with a replacement ratio of >20% and >40%, respectively. There was no difference in malondialdehyde (MDA) content in fish fed diets S10 to S50, which were lower than fish fed diet SO (P<0.05). There was no relationship between superoxide dismutase (SOD) activity and the fishmeal replacement ratio. In summary, our results suggest that alfalfa protein concentrate can replace up to 19.0% fishmeal protein in the diets of juvenile starry flounder.%研究了紫花苜蓿浓缩叶蛋白替代0％(S0)、10％ (S10)、20％(S20)、30％(S30)、40％(S40)、50％(S50)的鱼粉蛋白对星斑川鲽(Platichthys stellatus)幼鱼生长、体组成及血液生化指标的影响.实验幼鱼体质量(83.0±0.20)g.结果显示:1)当替代比例≤20％时,各组间星斑川鲽幼鱼特定生长率(SGR)、日摄食率(DFI)、饲料效率(FE)和蛋白质效率(PER)均无显著变化,高于此值时呈显著下降(P＜0.05).随饲料中紫花苜蓿浓缩叶蛋白替代鱼粉比例的升高,鱼体肥满度(CF)呈显著下降趋势(P＜0.05),而消化道指数(DTI)则呈显著上升趋势(P＜0.05)；各实验组干物质、蛋白质及脂肪表观消化率均呈直线下降趋势(P＜0.05).以星斑川鲽幼鱼特定生长率(SGR)为参考指标,采用折线回归分析得出,在本实验条件下,星斑川鲽幼鱼获得最佳生长时紫花苜蓿浓缩叶蛋白替代鱼粉蛋白的适宜比例为19.0％.2)紫花苜蓿浓缩叶蛋白替代鱼粉对星斑川鲽幼鱼肌肉水分、蛋白及粗灰分含量未产生显著性影响,肌肉脂肪含量仅S40组显著低于S0和S20组,其他各组间无显著差异；当替代比例小于20％时,肝脏水分呈显著上升趋势(P＜0.05),之后趋于平稳(P＞0.05).肝脏粗脂肪变化趋势与此相反.肝脏粗蛋白含量仅表现为S30、S50组显著高于S0组(P＜0.05),其他各组无显著差异(P＞0.05).肝脏粗灰分含量不受饲料鱼粉替代比例的影响(P＞0.05)；全鱼水分呈显著上升趋势(P＜0.05),而粗脂肪含量呈显著下降(P＜0.05).S30组全鱼粗蛋白最高,S40组最低(P＞0.05),除S30组外,其他各组均与S0组间无显著性差异(P＞0.05).各组间全鱼粗灰分含量变化不显著(P＞0.05).3)当替代比例＞20％时,星斑川鲽幼鱼血浆甘油三酯(TG)含量呈显著降低.各组间胆固醇(CHO)含量随紫花苜蓿浓缩叶蛋白的添加呈直线下降趋势(P＜0.05).当替代比例≥20％时,碱性磷酸酶(ALP)活性有下降趋势(P＜0.05).当替代比例分别大于20％和40％时,谷草转氨酶(AST)和谷丙转氨酶(ALT)活性显著升高但各组间差异不显著(P＞0.05).实验鱼血浆溶菌酶(LSZ)活力随鱼粉替代比例的升高呈显著上升(P＜0.05).各实验组间血浆丙二醛(MDA)含量无显著差异,但均低于S0组(P＜0.05),超氧化物歧化酶(SOD)活性不受紫花苜蓿浓缩叶蛋白替代鱼粉比例的影响(P＞0.05).结论认为,在本实验条件下,星斑川鲽幼鱼获得最佳生长时紫花苜蓿浓缩叶蛋白替代鱼粉蛋白的适宜比例为19.0％.
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