大规格鲈鱼(Lateolabrax japonicas)对饲料中花生四烯酸的需求量

Requirement of Arachidonic Acid in Adult Japanese Seabass(Lateolabrax japonicas)

选用初始体重(207.16±0.72)g的鲈鱼(Lateolabrax japonicas)为研究对象,研究大规格鲈鱼对花生四烯酸(Arachidonic acid,ARA)的最适需求量。通过在基础饲料中添加ARA?纯化油,制成ARA含量分别为0.05%、0.22%、0.37%、0.60%、1.38%及2.32%(占饲料干重)的6组等氮等能的实验饲料,进行为期84 d的生长实验。实验结束后,通过测定鲈鱼生长、体成分、抗氧化及肝脏健康等指标综合评价鲈鱼对饲料中花生四烯酸的需求量。结果显示,鲈鱼成活率在不同处理组之间无显著差异(P>0.05);鲈鱼的特定生长率(SGR)随着饲料中ARA含量的升高,呈先升高后相对平稳的趋势(P<0.05),且在ARA含量为0.37%饲料组出现最大值,饲料效率(FE)呈现出与特定生长率相同的趋势;饲料中不同ARA含量对鲈鱼的肝体比(HSI)、脏体比(VSI)、肥满度(CF)均无显著性影响(P>0.05);鱼体粗脂肪含量随着饲料ARA含量升高呈先减少后增加的趋势,粗蛋白含量则呈现出相反趋势;随着饲料ARA含量的升高,血清和肝脏中超氧化物歧化酶(SOD)活力呈现先升高后降低的趋势(P<0.05),肝脏和血清中丙二醛(MDA)含量则呈现先降低后升高的变化趋势(P<0.05);血清中谷草转氨酶和谷丙转氨酶活性均在0.37%ARA水平时显著低于对照组(P<0.05)。以特定生长率与饲料效率作为评定指标,经折线模型分析得出,(207.16±0.72)g规格的鲈鱼对饲料中ARA的最适需求量均为饲料干重的0.37%。

It has been clear that the dietary arachidonic acid （ARA） is essential in the growth of juvenile Japanese seabass （Lateolabrax japonicas）, and the requirement of ARA could vary at different growth stages. A 12-week feeding experiment was conducted to investigate the optimal level of ARA in diet of Japanese seabass [mean initial weight （207.16±0.72） g）]. Six isonitrogenous and isoenergetic diets were formulated with graded levels of dietary ARA, 0.05%, 0.22%, 0.37%, 0.60%, 1.38% and 2.32%, respectively. Triplicate groups of 20 fish were fed to apparent satiation twice daily. The water temperature ranged from 23 to 30.5℃, the salinity from 26 to 31 and the dissolved oxygen content was approximately 6.5 mg/L during the experimental period. The results showed that no significant differences in survival rate （93.33%-98.33%） were found among dietary treatments （P〉0.05）. With the increase of dietary ARA levels, the specific growth rate （SGR） and feed efficiency （FE） increased at first, and then kept steady after reaching their peaks at the 0.37% dietary ARA level （P〈0.05）. No significant differences were found in hepatosomatic index （HSI）, viscerasomatic indexes （VSI） and condition factor （CF） among dietary treatments （P〉0.05）. The body composition analysis showed that the whole-body protein content first increased and, then decreased with increasing dietary ARA, while the whole-body lipid content followed the opposite pattern. With the increase of dietary ARA levels, the activities of superoxide dismutase （SOD） in serum and liver significantly increased at first and then showed a declining tendency （P〈0.05）, but the malondialdehyde （MDA） contents in serum and liver had a converse trend with SOD （P〈0.05）. The activities of glutamic-oxaloacetic transaminase （GOT） and glutamic-pyruvic transaminase （GPT） in serum observably decreased when the dietary ARA level increased from 0.05% to 0.37%, and then increased when the dietary ARA level increased from 0.37% to 2.32% （P〈0.05）. The broken-line model analysis based on S GR and FE indicated that the optimal level of dietary ARA for Japanese seabass of （207.16±0.72） g of the diet was 0.37%.