鲤幼鱼饲料中DHA的适宜添加量研究

Dietary DHA requirement of juvenile Cyprinus carpio

在鲤鱼幼鱼（Cyprinus carpio）饲料中添加富含二十二碳六烯酸（DHA）的微藻粉,研究DHA对鲤生产性能及血清学指标的影响,确定适宜的添加量。将初始均质量（11.31±0.24）g的鲤幼鱼750尾,随机分为5组（Ⅰ~Ⅴ组）,每组设3个重复,每个重复50尾,分别投喂5个水平DHA（Ⅰ组：0%、Ⅱ组：0.17%、Ⅲ组：0.35%、Ⅳ组：0.71%、Ⅴ组：1.42%）的蛋白含量为36.14%、脂肪含量为13.12%饲料,进行为期60 d试验。结果表明：与Ⅰ组对比,随着添加DHA水平的升高,特定生长率（SGR）先升后降,Ⅲ组显著高于Ⅰ、Ⅱ、Ⅳ、Ⅴ组（P〈0.05）,分别提高21.88%、9.2%、5.8%和30.62%,二次回归分析得出,饲料中DHA最佳添加水平为0.65%;饵料系数（FCR）随着饲料DHA水平的增加先降后升,Ⅲ组最低,显著低于其它组（P〈0.05）,分别降低10.63%、5.92%、7.74%和14.37%;蛋白质效率（PER）与SGR变化相似;随饲料DHA水平上升,总蛋白、白蛋白、球蛋白的含量及溶菌酶、超氧化物歧化酶、过氧化氢酶活性呈上升趋势,胆固醇、甘油三酯先升后降,谷草转氨酶、谷丙转氨酶活性先降后升,血糖先增加后显著降低。在本试验条件下,鲤幼鱼适宜饲料DHA含量为0.65%。

Abstract： The function of DHA on productive performance and serum biochemical indices of juvenile Cyprinus carpio and its optimal addition were studied by incorporating DHA into feed. Five 36.20% crude protein and 52.31%crude llpid experimental dies were formulated to contain five DHA （0, 0.17%, 0.35%, 0.71%, 1.42%, respectively）. Seven hundred fifty juvenile [average weight （11.31±0.24） g] were randomly distributed in five treatments in triplicate groups with 50 fish per replicate for 60 d. With the increase of dietary DHA levels, specific growth were significantly higher （21.88%, 9.2%, 5.8%, and rate （SGR） increased firstly, then decreased, and 30.62%） in treatment m than that in treatments Ⅰ , Ⅱ ,Ⅳ, Ⅴ （P〈O.05）. Analysis of SGR by the polynomial equations regression analysis suggested that the di- etary DHA requirement for optimal growth in Cyprinus earpio is 0.65%. Feed conversion ratio （FCR）, with the best in treatment Ⅲ, decreased with increasing levels of dietary DHA up to 0.35% and showed a increasing tendency thereafter. Protein efficiency ratio （PER） showed an opposite trend with FCR and was remarkably higher in treatment Ⅲ than that in treatment Ⅰ , Ⅱ ,Ⅳ, Ⅴ（P〈0.05）. The FCR of group Ⅲ was lower than that of Ⅰ , Ⅱ ,Ⅳ, Ⅴ （10.63%, 5.92%, 7.74%, and 14.37%, respectively）. The tread of total protein, Albumin, Globulin, LZS, SOD and CAT in serum increased with the increase of dietary DHA levels, while cholesterins and riglycerides increased with the increase of dietary of DHA up to 0.35% and showed a declining tendency thereafter. The aspartate aminotransferase and alanine transaminase showed an opposite trend with cho- lesterins and riglycerides. First slightly increased the blood glucose and decreased significantly thereafter. In conclusion, Analysis of SGR by polynomial equations regression analysis suggest- ed that the dietary DHA requirement for optimal growth in juvenile Cyprinus carpio is 0.65%.