Zhu Yuxiang, Liao Kai, Huang Hailong, Liu Yang, Zhang Yang, Chen Deshui, Ma Bin, Xu Jilin
School of Marine Sciences, Ningbo University, Ningbo 315211, China.
Fujian Dalai Seed Science and Technology Co., Ltd, Ningde 352101, China.
Aquac Nutr. 2024 Oct 28;2024:9107191. doi: 10.1155/2024/9107191. eCollection 2024.
Dietary docosahexaenoic acid (DHA) is crucial for the optimal (Opt) growth of bivalves, but the precise dietary DHA requirement remains undetermined in bivalves. Our study identifies the optimal dietary DHA requirement for razor clam and demonstrates its effects on fatty acid profiles and gene expression related to inflammation and detoxification. Microencapsulated feeds with different DHA levels (DHA1-6 groups: 1.68, 4.85, 9.49, 12.6, 15.59, and 16.95 mg g dry matter) were prepared using spray drying. Razor clams (initial wet weight: 3.8 ± 0.6 mg) were fed these microcapsules for a period of 20 days. The present study showed that the clams in the DHA1 group exhibited significantly lower weight and shell length gain rates compared to those in the DHA3, DHA4, DHA5, and DHA6 groups. Based on the shell length gain rate, the Opt dietary requirement of DHA for clam is approximately 6.42 mg g dry matter. The clams in the DHA2 group had significantly higher crude lipid content compared to those in the DHA1 and DHA6 groups, while the clams in the DHA1 group had the highest ash content, significantly higher than that in the DHA4 and DHA6 groups. The DHA levels in the clams increased with the increase in DHA content in the microcapsules, while the levels of total -6 polyunsaturated fatty acids (PUFAs), linoleic acid (LA), and alpha-linolenic acid (ALA) decreased. The mRNA levels of () and were higher in the DHA1 and DHA6 groups compared to other microcapsule groups. As dietary DHA levels increased, the mRNA levels of ) and ) decreased. Additionally, the mRNA levels of catalytic subunit () and () were highest in the DHA1 group. This is the first study to determine the Opt DHA requirement for juvenile razor clams using microcapsules with different DHA levels, and this study further reveals that dietary DHA can help reduce inflammation and oxidative status in clams.
膳食二十二碳六烯酸（DHA）对双壳贝类的最佳生长至关重要，但双壳贝类的精确膳食DHA需求量仍未确定。我们的研究确定了缢蛏的最佳膳食DHA需求量，并证明了其对脂肪酸谱以及与炎症和解毒相关的基因表达的影响。使用喷雾干燥法制备了不同DHA水平的微胶囊饲料（DHA1 - 6组：每克干物质含1.68、4.85、9.49、12.6、15.59和16.95毫克DHA）。将缢蛏（初始湿重：3.8±0.6毫克）投喂这些微胶囊20天。本研究表明，与DHA3、DHA4、DHA5和DHA6组相比，DHA1组的缢蛏体重和壳长增长率显著更低。基于壳长增长率，缢蛏对DHA的最佳膳食需求量约为每克干物质6.42毫克。DHA2组的缢蛏粗脂肪含量显著高于DHA1和DHA6组，而DHA1组的缢蛏灰分含量最高，显著高于DHA4和DHA6组。缢蛏体内的DHA水平随着微胶囊中DHA含量的增加而升高，而总ω-6多不饱和脂肪酸（PUFA）、亚油酸（LA）和α-亚麻酸（ALA）水平则下降。与其他微胶囊组相比，DHA1和DHA6组中（）和（）的mRNA水平更高。随着膳食DHA水平的升高，（）和（）的mRNA水平下降。此外，DHA1组中催化亚基（）和（）的mRNA水平最高。这是第一项使用不同DHA水平的微胶囊来确定幼体缢蛏最佳DHA需求量的研究，并且该研究进一步揭示了膳食DHA有助于降低缢蛏体内的炎症和氧化状态。
