养殖和野生亚东鲑机体成分比较分析

Composition analysis of farmed and wild Yadong trout (Salmo trutta fario)

中文关键词: 亚东鲑  野生  养殖  营养成分  氨基酸  脂肪酸

英文关键词: Salmo trutta fario  Wild  Farmed  Nutrient composition  Amino acid  Fatty acid

中文摘要:

      亚东鲑(Salmo trutta fario)是鲑属鱼类在青藏高原仅有的鱼类种群，是亚东地区全国农产品地理标志产品。本研究对西藏亚东地区野生和养殖亚东鲑的常规营养成分及各组织氨基酸和脂肪酸组成进行分析，旨在比较野生和养殖亚东鲑营养成分的异同，为养殖亚东鲑的品质评价和饲料配方的完善提供参考信息。实验采集亚东河中野生亚东鲑和亚东渔业产业园中使用配合饲料养殖的亚东鲑各10尾用于相关成分分析，每尾为一个独立样本。结果显示，野生组肥满度显著低于养殖组，而全鱼水分和灰分显著高于养殖组。全鱼粗蛋白、粗脂肪以及肝脏常规成分在野生组和养殖组间无显著差异。野生组肌肉粗脂肪显著低于养殖组，而水分含量显著高于养殖组。野生组全鱼必需氨基酸总量显著高于养殖组，且野生组肌肉中苏氨酸、缬氨酸、苯丙氨酸、赖氨酸和甘氨酸含量显著高于养殖组。野生组全鱼、肌肉和肝脏中饱和脂肪酸、n-3多不饱和脂肪酸(n-3 PUFA)总量、EPA、C20:4n-6以及肌肉中DHA含量高于养殖组，而全鱼和组织中单不饱和脂肪酸和n-6 PUFA总量低于养殖组。综上所述，目前养殖亚东鲑和野生亚东鲑在机体成分上存在较大差异。由于养殖鱼类体成分很大程度上反映了饲料组成，因此，亚东鲑养殖中饲料营养组成可能有待进一步优化。

英文摘要:

      Yadong trout (Salmo trutta fario), the only salmonid fish in the Tibetan Plateau, is a national agricultural product with geographical indications in Yadong. The development of Yadong trout aquaculture has significant implications for local farmers. However, no study has yet investigated the nutrient requirements of this fish. This study aimed to analyze the proximate amino acid, and fatty acid composition of various tissues of wild and farmed Yadong trout, in order to provide a reference for the evaluation of fish fillets and the formulation of optimal feed. Ten wild fish captured in the Yadong River, and 10 fish farmed with formulated feed in Yadong Industry Park were used in this study. The farmed fish were F1 generation wild broodstock captured in the Yadong River and fed formulated feeds throughout their lifetime. The body length of wild Yadong trout was in the range of 13.4~28.7 cm, and the body weight was in the range of 38.48~346.85 g. The body length and body weight of farmed Yadong trout were in the range of 16.4~24.5 cm and 78.39~275.29 g, respectively. Frozen samples were transported to the laboratory by flight. The proximate composition of whole fish, muscle, and liver; fatty acid composition of whole fish and various tissues including muscle, liver, intestine, brain, and eye; as well as amino acid composition of whole fish, muscle, and liver were analyzed. The fatty acid composition (expressed as % total fatty acids) and amino acid composition (expressed as % dry matter basis) were assayed using gas chromatography and an automatic amino acid analyzer, respectively. In addition, t-tests were performed for independent samples; results are expressed as the mean ± standard deviation. The results showed that wild fish had lower condition factors but higher moisture and ash content than farmed fish. Wild fish muscle had lower crude lipid content but higher moisture content than farmed fish. The whole-body protein and lipid contents, as well as the proximate composition of the liver, were not significantly different between wild and farmed fish (P>0.05). The contents of saturated fatty acids (mainly C16:0 and C18:0) and n-3 polyunsaturated fatty acid (PUFA) in whole fish, muscle, and liver were significantly higher (P<0.05), whereas contents of monounsaturated fatty acids (MUFA) (mainly C16:1n-7 and C18:1n-9) and n-6 PUFA (mainly C18:2n-6) were significantly lower in wild Yadong trout than in farmed Yadong trout (P<0.05). EPA and C20:4n-6 in whole fish, muscle, and liver, as well as DHA in the muscle of wild Yadong trout were significantly higher than those in farmed Yadong trout (P<0.05). In the intestine of wild Yadong trout, the contents of C14:0, C16:0, C18:0, C16:1n-7, C20:5n-3, and C22:5n-3 were significantly higher (P<0.05), while those of C18:1n-9 and C18:2n-6 were significantly lower (P<0.05) than in the farmed fish. In the brain of wild Yadong trout, the contents of C16:1n-7, C20:5n-3, and C22:5n-3 were significantly higher (P<0.05), while the contents of C18:1n-9 and C20:2n-6 were significantly lower (P<0.05) than those of farmed fish. In the eyes of wild Yadong trout, the contents of C14:0, C16:0, and C18:0, C16:1n-7, C20:1n-9, C20:2n-6, C20:4n-6, C20:5n-3, and C22:5n-3 were significantly higher (P<0.05), while the contents of C18:1n-9, C22:1n-9, C24:1n-9, C18:2n-6, and C18:3n-3 were significantly lower (P<0.05) than those of farmed Yadong trout. The total essential amino acid content in wild fish was significantly higher than that in farmed fish. The contents of threonine, valine, phenylalanine, lysine, and glycine in the muscle of wild fish were significantly higher (P<0.05) than those in farmed fish, while no significant difference (P>0.05) was observed in other amino acids. These results indicate that wild Yadong trout were leaner than farmed trout in terms of muscle lipid content. For trout, which are mainly consumed fresh, this trait may make farmed Yadong trout more acceptable than wild trout. However, in terms of fatty acid composition and amino acids, the wild Yadong trout seemed to be more acceptable than farmed trout. In particular, n-3 PUFA content is an important nutritional trait in fish fillets. The wild Yadong trout had higher n-3 PUFA contents than the farmed trout. Thus, the fish oil in the feeds of Yadong trout should not be omitted, considering that fish chemical composition generally reflects that of their diets. In addition, the price of alternative oils such as soybean oil is no longer low; the use of lipid sources in the diets of Yadong trout should be reviewed. Similarly, the essential amino acid content in wild Yadong trout was higher than that in the farmed trout, suggesting that the protein sources should be reviewed, and a certain level of fish meal should be guaranteed. In conclusion, the results of this study indicate that the formulated feeds of Yadong trout need to be further optimized.