网箱海养卵形鲳鲹饲料与肌肉品质评价

Evaluation of Nutritional Composition and Quality of Feed and Muscle of Sea Cage Cultured Trachinotus ovatu

本实验结合喂养饲料,对海水网箱养殖卵形鲳鲹肌肉进行常规生化分析,并对其营养品质进行评价。结果表明:饲料蛋白质、粗脂肪含量能满足其生长需求;养殖卵形鲳鲹肌肉中蛋白质、脂肪、灰分和水分含量分别为(19.48±0.15)%、(8.40±0.30)%、(1.34±0.06)%、(70.84±0.06)%,其脂肪含量高于其他鲳鱼;肌肉中氨基酸总量为(66.21±1.17)%(以干基计),其中必需氨基酸总量为(26.65±0.54)%,鲜味氨基酸含量为(25.50±0.54)%,其必需氨基酸的构成比例完全符合联合国粮食及农业组织/世界卫生组织评价标准,饲料和肌肉第一限制氨基酸均为蛋氨酸;肌肉中共检测出27种脂肪酸,多不饱和脂肪酸总量(polyunsaturated fatty acid,PUFA)、二十碳五烯酸(eicosapentaenoic acid,EPA)和二十二碳六烯酸(docosahexaenoic acid,DHA)含量分别为(32.72±0.05)%、(0.64±0.04)%和(5.05±0.23)%,其n-6与n-3 PUFA比值、PUFA/饱和脂肪酸总量(saturated fatty acid,SFA)均符合英国卫生部推荐要求。研究表明:养殖卵形鲳鲹肉味鲜美,必需氨基酸含量高、组成均衡,多不饱和脂肪酸、DHA含量较高,具有较高的食用和营养价值;饲料营养成分基本满足卵形鲳鲹生长需求,但若能调整该配合饲料的蛋氨酸含量、n-3系列脂肪酸含量,可进一步提高养殖卵形鲳鲹的肌肉品质。

In order to understand the nutritive quality and nutrient components in the muscle of seawater cultured Trachinotus ovatu, the main nutrient components in the muscle and feed of seawater cultured Trachinotus ovatu were analyzed in this work. Evaluation standards of nutritive quality were based on the Food and Agriculture Organization of the United Nations/Word Health Organization（FAO/WHO） standard mode. The general nutrient compositions were determined by routine methods. Amino acid compositions were determined with an amino acid analyzer. Fatty acid compositions were measured by gas chromatograph-mass spectrometry（GC-MS）. The results showed that crude protein and crude fat of fish feed basically met the nutritional requirements of Trachinotus ovatu. The contents of crude protein, crude fat, crude ash and moisture in fresh muscle of seawater cultured Trachinotus ovatu were（19.48 ± 0.15）%,（8.40 ± 0.30）%,（1.34 ± 0.06）% and（70.84 ± 0.06）%, respectively, while crude fat was higher than other fish species. In dry muscle sample, the total content of amino acids（TAA） was（66.21 ± 1.17）%, and the content of essential amino acids（EAA） was（26.65 ± 0.54）%. Four delicious amino acids（DAA） accounted for（25.50 ± 0.54）%, the ratio of total essential amino acids to total amino acids（EAA/TAA） was 40.25%, and the ratio of total essential amino acids to total nonessential amino acids（EAA/NEAA） was 67.36%. It was clear that the content of different amino acids was stable and the proportions of essential amino acids met FAO/WHO standards. According to nutrition evaluation in terms of amino acids score（AAS） and chemical score（CS）, the first limiting amino acid of both muscle and feed was methionine. In addition, 27 fatty acids were detected in the muscle of seawater cultured Trachinotus ovatu, with PUFA, EPA and DHA accounting for（32.72 ± 0.05）%,（0.64 ± 0.04）% and（5.05 ± 0.23）% of the total amount, respectively. The ratios of n-6/n-3 and PUFA/SFA in muscle indicated its food safety according to the values recommended by the UK Department of Health. Therefore, farmed Trachinotus ovatu is a species of fish with delicious taste, high content of essential amino acids, balanced nutrient composition, high nutrition value for human consumption and health benefits. This study showed that the present feed basically meet the requirements for farmed Trachinotus ovatu growth; however, the quality of farmed Trachinotus ovatus muscle may be improved by increasing the contents of methionine and n-3 series of fatty acids in the compound feed.