双低菜粕高水平替代饲料鱼粉对大黄鱼潜在风险的评估:生长、健康和营养价值

研究从生长、健康和营养价值方面评估了高水平的双低菜粕替代饲料鱼粉对大黄鱼潜在的危害。在鱼粉含量60%的基础饲料（FM）上按照质量分数用双低菜粕分别替代15%（CM15）、30%（CM30）、60%（CM60）和100%（CM100）的鱼粉，配制成5种实验饲料。每种饲料投喂5个网箱的大黄鱼初重（135.38±1.02）g]，即每个处理5个重复，进行12周的养殖实验。结果表明，当双低菜粕替代水平在15%和30%时，大黄鱼的生长及饲料系数并没有受到显著性的影响。然而，当替代水平高于30%时，大黄鱼的末重和特定生长率均显著降低，而饲料系数显著升高（P < 0.05）。当替代水平达到100%时，大黄鱼摄食率达到最高值而肥满度达到最低值（P < 0.05）。在组织形态方面，大黄鱼摄食双低菜粕替代的饲料后肠道绒毛的弯曲程度减少并且排列更加不规则，而肝细胞则呈现出圆形空泡状并伴随着细胞核的偏移。对大黄鱼骨骼进行X-射线扫描发现，摄食双低菜粕的大黄鱼椎体和头部出现了畸形。在营养价值方面，双低菜粕替代鱼粉并未显著影响大黄鱼背肌的脂肪含量、蛋白含量和氨基酸组成，然而脂肪酸组成受到了显著影响，即N-6系列脂肪酸含量显著升高，而DHA与EPA含量显著降低（P < 0.05）。根据欧洲食品安全局（EFSA）的相关标准，这些营养价值的变化并没有影响大黄鱼作为健康食品的功能。由此可见，高水平（60%和100%）的双低菜粕替代鱼粉对大黄鱼的负面影响主要表现为降低大黄鱼的生长性能、改变肠道和肝脏组织形态，以及影响大黄鱼的骨骼健康。然而，双低菜粕替代鱼粉养殖大黄鱼的肌肉仍然符合人类的膳食要求。因此，双低菜粕替代鱼粉并没有影响大黄鱼作为食用鱼的营养价值。

POTENTIAL RISKS OF HIGH LEVEL REPLACEMENT OF DIETARY FISH MEAL BY CANOLA MEAL ON LARGE YELLOW CROAKER LARIMICHTHYS CROCEA (RICHARDSON, 1846):GROWTH,HEALTH AND NUTRITIONAL VALUES AS A FOOD FISH

A growth trial was conducted to evaluate the potential risks of high levels replacement of dietary fish meal by canola meal on large yellow croaker Larimichthys crocea (Richardson, 1846). It focused on the growth, health and nutritional values as a food fish. Diet with 60%of fish meal was formulated as the control group (FM). The other four experimental diets were formulated with graded replacement levels of fish meal by canola meal according to mass fraction. These replacement levels included 15%(CM15), 30%(CM30), 60%(CM60) and 100%(CM100), respectively. The 5 experimental diets were fed to 5 groups of large yel-low croaker initial weight of (135.38±1.02) g] for 12 weeks. There were 5 replicates per group. Results showed that the growth and feed conversion ratio (FCR) of large yellow croaker was not significantly influ-enced when the replacement level of dietary fish meal by canola meal were 15%and 30%. However, values of final body weight and the specific growth rate significantly decreased and value of FCR significantly in-creased in groups of CM60 and CM100 (P<0.05). Feed intake increased significantly, while condition factor significantly decreased in CM100 group (P<0.05). Histologically, less twist and disorganized morphology in intestine, distinct circular vacuoles and nuclear perturbations in liver were found when fish was fed with cano-la meal included diets. Through the digital X-ray analysis of skeleton, both vertebral body and mouth deform-ities were found in fish fed with canola meal. As for nutritional values, no significant difference was ob-served in lipid content, protein content and amino acid profile of dorsal muscle. While fatty acid composi-tions were significantly changed in muscle. N-6 fatty acid contents significantly increased, and DHA and EPA contents decreased (P<0.05). Based on the standards of the European Food Safety Authority (EFSA), however, these changes didn’t influence the fact that large yellow croaker was also recommended as a healthy food fish. In summary, the negative impacts of high levels (60%and 100%) replacement of dietary fish meal by canola meal on large yellow croaker mainly related to the reduced growth performances, altered intestinal and hepatic morphology as well as impaired skeletal health. However, large yellow croaker fed with canola meal in diets still meet the standard of healthy food, thus canola meal replacement didn’t significantly influ-ence the nutritional value of large yellow croaker as a food fish.