不同年龄和性腺发育阶段圆口铜鱼营养成分组成分析

由于水电梯级开发和过度捕捞等人类活动影响，长江上游珍稀特有鱼类圆口铜鱼（Coreius guichenoti）资源量显著下降。增殖放流是保护该物种的有效途径之一，而人工繁育过程中为圆口铜鱼提供营养全面的饲料对其性腺发育至关重要。通过分析比较不同年龄和性腺发育阶段的圆口铜鱼肌肉营养成分、肌肉和性腺氨基酸组成，可为其人工饲料的开发提供基础数据。结果显示：(1)随着年龄的增长，圆口铜鱼肌肉粗蛋白、粗脂肪和氨基酸含量均呈先降低、后增加的趋势；(2)性腺从II 期到IV 期的发育过程中，圆口铜鱼肌肉粗蛋白、粗脂肪和氨基酸含量均升高；(3)性腺中谷氨酸和亮氨酸在所有氨基酸中的占比较高，分别为9.82%和6.74%，其中10 种氨基酸的含量、必需氨基酸总量和氨基酸总量均显著低于肌肉组织中的含（P<0.05），而每100 g 蛋白质中脯氨酸（3.19±0.22）g 和丝氨酸（3.56±0.27）g 含量显著高于肌肉组织中的含（P<0.05）。研究表明，圆口铜鱼肌肉营养成分、氨基酸组成与其年龄和发育期有着密切联系。随着性腺发育，其肌肉粗蛋白、粗脂肪和氨基酸含量呈增加趋势，谷氨酸、亮氨酸和脯氨酸在圆口铜鱼性腺发育过程中可能起关键作用。

Nutrient Composition Analysis of Coreius guichenoti at Different Ages and Gonad Development Stages

Cascaded hydropower projects and overfishing have dramatically reduced populations of Coreius guichenoti, a rare fish species endemic to the upper Yangtze River. The breeding and release of C. guichenoti has been an effective means of protecting the species. During artificial breeding, it is crucial to provide a comprehensive, nutritious feed for gonadal development. In this study, the nutrition of the muscle, and composition of amino acids in the muscle and gonads at different ages and gonad development stages of C. guichenoti were compared and analyzed The goal was to provide basic data for improving the artificial diet. The test fish were taken from a net cage fixed inside the boat in the Luzhou section of Yangtze River in May 2018. The weight, body length and total length, age and gonad development stage of each fish were recorded, and the muscle and gonad were sampled for the determination of nutrient and amino acid composition. Results show that: (1) Between different age groups, there were no significant differences with respect to the muscle content of crude protein, crude fat and amino acids. With increasing age, the muscle content of crude protein, crude fat and amino acids initially decreased and then increased. (2) During gonadal development from stage II to IV, the muscle content of crude protein, crude fat and amino acids increased. (3) 17 amino acids were detected in muscle and gonad tissues, including 7 essential amino acids and 10 non-essential amino acids. In gonad tissue, the content of glutamic and leucine were highest, accounting for 9.82% and 6.74% of the total amino acid content. The essential amino acid and the total amino acid contents in gonad tissue were significantly lower than in muscle tissue (P<0.05), while the contents of proline (3.19±0.22) g and serine (3.56±0.27) g per 100 g protein were significantly higher than that in muscle (P<0.05). These results indicate that the nutrient levels of C. guichenoti are closely related to age and gonad development stage. With gonad development, the contents of crude protein, crude fat and amino acids tended to increase. Glutamic, leucine and proline could play a key role in gonad development of C. guichenoti.