饲料中添加桑叶黄酮对吉富罗非鱼生长性能、体成分、抗氧化指标及抗亚硝酸盐应激能力的影响

本试验旨在研究饲料中添加桑叶黄酮对吉富罗非鱼(Oreochromis niloticus)幼鱼生长性能、体成分、血清和肝脏抗氧化指标及抗亚硝酸盐应激能力的影响。选取初始体重为(1.51±0.02)g的吉富罗非鱼840尾,随机分为6组,每组4个重复,每个重复35尾鱼。对照组饲喂基础饲料,试验组分别在基础饲料中添加50、100、300、500和1 000 mg/kg的桑叶黄酮。饲养期56d。饲养试验结束后,各组采用亚硝酸钠进行72h应激试验。结果表明:1)各组间吉富罗非鱼增重率、饲料系数、蛋白质效率均差异不显著(P0.05)。各组间吉富罗非鱼鱼体水分、粗蛋白质、粗脂肪和粗灰分含量均差异不显著(P0.05)。2)试验组血清超氧化歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活性和总抗氧化能力(T-AOC)均高于对照组,其中100、300、500和1 000mg/kg桑叶黄酮组血清SOD活性,50、500、1 000 mg/kg桑叶黄酮组血清GSH-Px活性及100、500mg/kg桑叶黄酮组血清T-AOC显著高于对照组(P0.05)。与对照组相比,试验组血清丙二醛(MDA)含量均显著降低(P0.05)。100、300和500mg/kg桑叶黄酮组肝脏过氧化氢酶(CAT)、SOD活性和T-AOC显著高于对照组(P0.05);肝脏GSH-Px活性以500 mg/kg桑叶黄酮组最高,显著高于1 000mg/kg桑叶黄酮组(P0.05)。3)亚硝酸盐氮应激48和72h,50、100、500mg/kg桑叶黄酮组的累计死亡率显著低于对照组(P0.05)。由此可见,饲料中添加桑叶黄酮对吉富罗非鱼生长性能没有显著影响,但提高了血清和肝脏抗氧化指标及抗亚硝酸盐应激能力。本试验条件下,通过回归方程分析,以血清SOD活性、T-AOC为评价指标,得出吉富罗非鱼幼鱼饲料中桑叶黄酮适宜添加水平为100 mg/kg;以肝脏SOD活性、T-AOC为评价指标,得出吉富罗非鱼幼鱼饲料中桑叶黄酮适宜添加水平为371.00~441.75mg/kg。

Effects of Dietary Mulberry Leaf Flavonoids on Growth Performance,Body Composition,Antioxidant Indices and Resistance to Nitrite Exposure of Genetic Improvement of Farmed Tilapia (Oreochromis niloticus)

This experiment was conducted to investigate the effects of dietary mulberry leaf flavonoids (MLF) on growth performance,body composition,serum and liver antioxidant indices and resistance to nitrite exposure of juvenile genetic improvement of farmed tilapia (GIFT,Oreochromis niloticus).A total of 840 GIFT with an initial body weight of (1.51±0.02) g were randomly divided into 6 groups with 4 replicates per group and 35 fish per replicate.Fish in the control group were fed a basal diet,and the others in the experimental groups were fed basal diets supplemented with 50,100,300,500 and 1 000 mg/kg MLF,respectively.The feeding trial lasted for 56 days.After the feeding trial,sodium nitrite was used to conduct a nitrite exposure trial in each group for 72 h.The results showed as follows: 1) there were no significant differences on the weight gain ratio (WGR),feed conversion ratio (FCR) and protein efficiency rate (PER) of GIFT among all groups.(P>0.05).There were no significant differences in the crude protein,crude lipid,ash and moisture contents of GIFT whole body among all groups (P>0.05).2) The serum superoxide dismutase (SOD),glutathione peroxidase (GSH-Px) activities and total antioxidant (T-AOC) in experimental groups were higher than in control group.The serum SOD activities in 100,300,500,and 1 000 mg/kg MLF groups were significantly higher than those in control group (P<0.05),the serum GSH-Px activities in 50,500 and 1 000 mg/kg MLF groups were significantly higher than those in control group (P<0.05),the serum T-AOC in 100 and 500 mg/kg MLF groups were significantly higher than those in control group (P<0.05).Compared with the control group,the serum malondialdehyde (MDA) contents in experimental groups were significantly decreased (P<0.05).The liver SOD,catalase (CAT) activities and T-AOC in 100,300 and 500 mg/kg MLF groups were significantly higher than those in control group (P<0.05).The highest value of liver SOD activity was observed in 500 mg/kg MLF group,and significantly higher than that in 1 000 mg/kg MLF group (P<0.05).3) After 48 and 72 h nitrite exposure,the cumulative mortality rates in 50,100 and 500 mg/kg MLF groups were significant lower than those in control group (P<0.05).In conclusion,dietary MLF do not significantly affect the growth performance,but improve the serum and liver antioxidant indices and resistance to nitrite exposure of GIFT.Under the experimental conditions,by analysis of the regression equation,the optimal supplemental level of MLF in the diet of juvenile GIFT is 100 mg/kg basis of SOD activity and T-AOC in serum;the optimal supplemental level of MLF in the diet of juvenile GIFT is 371.00 to 441.75 mg/kg basis of SOD activity and T-AOC in liver.