共轭亚油酸对珍珠龙胆石斑鱼幼鱼生长、体组成及肝代谢相关酶活力的影响

摘要

We investigated how conjugated linoleic acids (CLA) can affect the growth, body composition and me-tabolism-related hepatic enzyme activities of juvenile hybrid grouper (♀Epinephelus fuscoguttatus×♂E. lanceolatu). Fishes with initial body weight of (63.57±0.56) g were examined after 8 weeks of feeding with isoni-trogenous and isolipidic diets in which 0 (CLA0), 0.8% (CLA0.8), 1.6% (CLA1.6), 2.4% (CLA2.4) and 3.2% (CLA3.2) of conjugated linoleic acid were supplemented. The results showed that: (1) there were no significant differences in weight gain ratio (WGR), survival rate (SR), specific growth rate (SGR), condition factor (CF), hepatosomatic index (HIS) and viscerosomatic index (VSI). The protein efficiency ratio (PER) increased as levels of dietary CLA rose, and was significantly higher in all experimental groups than in CLA0 groups (P<0.05). Feed intake (FI) was reduced with increasing dietary CLA; FI in group CLA0 was significantly higher than that in other groups (P<0.05). Feed conversion ratio (FCR) was decreased, and achieved in the group CLA2.4, which was sig-nificantly lower than CLA0 (P<0.05); (2) muscle fat content increased as amounts of dietary CLA rose, and the achieved in the group CLA0.8, which was significantly lower than that in group CLA0 (P<0.05). Liver fat content was not significant (P>0.05). The content of saturated fatty acid (SFA) and C18:0 in the muscle of group CLA1.6 was significantly higher than in group CLA0 (P<0.05), and monounsaturated fatty acid (MUFA) content in CLA3.2 achieved minimum as well as C18:1n-9, which was significantly lower than that of control group (P<0.05). Liver content of C16:0 and C18:0 in groups CLA2.4 and CLA3.2 were significantly higher than in the control group (P<0.05); however, C16:1n-7, C18:1n-9 and C18:1n-7 content were significantly lower than in group CLA0 (P<0.05). C18:3n-3and C18:2n-6content of muscle and liver in groups CLA2.4 and CLA3.2 were significantly lower than in group CLA0 (P<0.05). C18:2c9, t11 and C18:2t10, c12 content in muscle and liver were highly related with dietary CLA supplement, and in all experimental groups were significantly higher than in CLA0 groups (P<0.05); (3) dietary conjugated linoleic acid levels among glucose-6-phosphatedehydrogenase (G6PD) activity in the experimental groups were significantly higher than those in the control group (P<0.05); acyl-coenzyme aoxidase activity has the highest CLA3.2 activity, which was higher than in the other groups (P<0.05); general esterase and fatty acids yn-thetase activity in the experimental groups was significantly higher than in the control group (P<0.05).The results indicate that dietary CLA can significantly improve the utilization of aquafeed by juvenile hybrid grouper, impr-ove the composition of fatty acids in liver and muscle, and increase metabolism-related hepatic enzyme activities.%珍珠龙胆石斑鱼(Epinephelus fuscoguttatus♀×E. lanceolatu♂)是鞍带石斑鱼(♂E. lanceolatu)与棕点石斑鱼(♀E. fuscoguttatus)杂交出的新品种。本研究用共轭亚油酸(CLA)添加量为0(CLA0)、0.8%(CLA0.8)、1.6%(CLA1.6)、2.4%(CLA2.4)、3.2%(CLA3.2)的5种等氮等能饲料,投喂初始体重为(63.57±0.56) g珍珠龙胆石斑鱼幼鱼8周,研究不同共轭亚油酸水平对其生长、体组成及肝代谢相关酶活的影响。结果表明：(1)添加共轭亚油酸对实验鱼增重率、成活率、特定生长率、肥满度、肝体比和脏体比无显著影响；蛋白质效率随着饲料中共轭亚油酸水平的升高而升高,其他各组显著高于CLA0组(P<0.05)；摄食率随着饲料中共轭亚油酸水平的升高而降低, CLA0组显著高于其他各组(P<0.05)；饲料系数呈降低趋势,在CLA2.4组达到最低,显著低于CLA0组(P<0.05)。(2)肌肉脂肪含量随饲料CLA水平的升高而升高,除CLA0.8组外,其他各组显著高于CLA0组(P<0.05),肝脂肪含量随着饲料 CLA 含量的变化未见显著性差异。CLA1.6组肌肉中饱和脂肪酸和 C18：0含量显著高于 CLA0组(P<0.05), CLA3.2组单不饱和脂肪酸和C18：1n-9显著低于CLA0组(P<0.05)。CLA2.4组和CLA3.2组肝中C16：0和C18：0含量显著高于CLA0组(P<0.05),而C16：1n-7、C18：1n-9和C18：1n-7含量显著低于CLA0组(P<0.05)。CLA2.4组和CLA3.2组肌肉和肝中C18：3n-3和C18：2n-6在显著低于CLA0组(P<0.05)。肌肉和肝中C18：2c9, t11和C18：2t10, c12含量同共轭酸添加水平呈现高度正相关,且各添加组均显著高于CLA0组(P<0.05)。(3)饲料中共轭亚油酸水平影响葡萄糖-6-磷酸脱氢酶(G6PD)的活性,各实验组均显著高于CLA0组(P<0.05)；饲料中共轭亚油酸水平影响酰基辅酶A氧化酶(ACO)的活性,其中CLA3.2活性最高,均高于其他组(P<0.05)；除CLA0.8组的总酯酶和脂肪酸合成酶活力低于CLA0组外,其他各组均高于 CLA0组(P<0.05)。实验结果表明,日粮中适量添加 CLA 可显著提高珍珠龙胆石斑鱼幼鱼对饲料的利用,改善肌肉和肝中脂肪酸组成,同时增加肝脂肪代谢相关酶的活性。