饲料脂肪水平对宽体沙鳅幼鱼生长和肌肉脂肪酸组成及脂肪酶的影响

On Effects of Dietary Lipid Level on Growth, Fatty Acids Profiles and Lipase in Botia Reevesae

为确定宽体沙鳅Botia reevesae最适饲料脂肪水平需求,以鱼油和豆油1∶1混合作为脂肪源,采用脂肪水平分别为1.92%,3.83%,6.11%,8.62%和11.94%的5种等氮配合饲料饲喂宽体沙鳅幼鱼,进行为期210 d的生长实验,分析了饲料脂肪水平对宽体沙鳅的生长、肌肉脂肪酸及肠道脂酶活性的影响.结果表明:饲料脂肪水平从1.92%增加到8.62%能显著促进宽体沙鳅幼鱼的生长(p<0.05).肠道脂蛋白酯酶及肝脂肪酶活性随饲料脂肪水平的升高而增加,组间差异显著(p<0.05).6.11%,8.62%和11.94%组肌肉中20:5n-3,22:6n-3比例显著低于1.92%和3.83%组(p<0.05),而6.11%,8.62%和11.94%组18:2n-6,18:3n-6,18:3n-3显著高于1.92%和3.83%组(p<0.05),∑MUFA,∑PUFA和∑n-6比例随饲料脂肪质量分数增加而升高,但∑n-3比例下降.实验结果表明,提高饲料脂肪水平能促进宽体沙鳅的生长,增加饲料豆油质量分数能显著降低宽体沙鳅肌肉中的20:5n-3和22:6n-3.折线回归方程得出宽体沙鳅幼鱼的最适脂肪水平为10.84%.

Dietary lipid plays an important role in commercial diet as a source of energy and essential fatty acids for the growth and reproduction of fish. The present study has been conducted to investigate the effect of different lipid levels in early juvenile of Botia reevesae with regard to growth, fish body eornposi tion, and fatty acid profiles in muscle and lipid metabolism enzyme activities at the end of the trial. Five isonitrogenous diets containing lipids of 1.92%, 3.83%, 6.11%, 8.62% and 11.94% have been formula- ted respectively. Each diet has randomly been assigned to triplicate groups of tanks, and each tank stocked with 50 fish（30 days after hatchery, with initial average weight 0.23±0.07 g）. Fish are fed to satiation two times daily for 210 days. The results show that dietary lipid significantly has affected the growth of B. reevesae （p〈0.05）. Specific growth rates（SGR）of B. reevesae increase with the increase of dietary lipid level from 1.92% to 8.62%, and then show a threshold. With the increase of lipid level in dietary, the ration of C20.5n-3, C22：6n-3 and ∑n-3 decreased in muscle, and the ration of C18：2n-6, C18.3n-6, C18. 3n-3, C20.3n-6 and ∑n-6 increased in muscle. Intestine lipase, lipoprotein lipase （LPL）, and hepatic lipase（HL）activities tended to firstly significantly increased in 6.11%, 6.11% and 3.83% groups, respectively, and then all decrease at 11.94% treatment. Broken-line analysis based on SGR indicated that the optimal dietary lipid level for the early juvenile of B. reevesae is 10. 84%. The results show the lipid level of soybean oil could decrease n-3 polyunsaturated fatty acid（n-3 PUFA）, and increase n-6 PUFA.