饲料亚麻酸含量对日本沼虾生长、抗氧化能力、非特异性免疫性能及抗氨氮胁迫能力的影响

亚麻酸(C18∶3n-3,LNA)作为一种重要的多不饱和脂肪酸,对甲壳动物生长、免疫保护和抵抗环境胁迫具有重要的调节作用。本试验旨在研究饲料LNA含量对日本沼虾生长、抗氧化能力、非特异性免疫性能和抗氨氮胁迫能力的影响,探讨日本沼虾饲料中适宜的LNA含量。试验配制LNA含量分别为0(L0,对照)、0.5%(L0.5)、1.0%(L1.0)、1.5%(L1.5)、2.0%(L2.0)和2.5%(L2.5)的6种等氮等脂的半纯化饲料,饲喂初始体重为(0.12±0.01)g日本沼虾幼虾8周。每种饲料投喂5个水族箱(重复),每个水族箱放养50尾试验鱼。饲养试验结束后,从每个水族箱选取10尾试验鱼进行24 h氨氮(水体总氨氮浓度为36.6 mg/L)胁迫试验。结果表明:日本沼虾特定生长率、增重率和存活率均随饲料LNA含量的增加呈先升后降的趋势,但组间差异不显著(P0.05)。LNA的含量在肝胰腺和肌肉中都随饲料LNA含量的增加而增加。随着饲料中LNA含量的增加,日本沼虾肝胰腺超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GSH-Px)活力和总抗氧化能力(T-AOC)基本呈现先升后降的趋势,且均在L1.0组达到最高值。L0.5、L1.0、L1.5、L2.0和L2.5组肝胰腺丙二醛(MDA)含量显著低于L0组(P0.05)。肝胰腺碱性磷酸酶(ACP)活力以L1.0组最高,但L1.0和L1.5组之间不存在显著性差异(P0.05)。随着饲料LNA含量的增加,肝胰腺溶菌酶(LYZ)活力呈先升后降的趋势,在L1.5组达到最高,显著高于其他各组(P0.05)。24 h氨氮胁迫后,L0.5、L1.5、L2.0、L2.5组的肝胰腺M DA含量显著低于L0组(P0.05),且以L1.5组M DA含量最低,显著低于其余各组(P0.05);肝胰腺SOD活力和T-AOC随着饲料LNA含量的增加呈先上升后下降趋势,L1.5组SOD活力达到最高,L1.0组T-AOC达到最高;肝胰腺GSH-Px活力以L0组最高,但与L1.0组差异不显著(P0.05)。以肝胰腺SOD活力为指标,经二次回归分析得出日本沼虾的LNA需要量为1.19%。综上,饲料中适宜的LNA含量(1.0%~1.5%)能改善日本沼虾的生长,增强其抗氧化能力和非特异性免疫性能,缓解氨氮胁迫对其造成的负面影响。

Effects of Dietary Linolenic Acid Content on Growth,Antioxidant Capacity,Non-Specific Immunity and Anti-Ammonia-Nitrite Stress Ability of Oriental River Prawn (Macrobrachium nipponense)

Linolenic acid ( C18∶3n?3, LNA) is one of the important polyunsaturated fatty acids ( PUFA) for the regulation of growth, immunity and environmental stress resistance of crustacean. This experiment was in?vestigated to study the effects of dietary LNA content on growth, antioxidant capacity, non?specific immunity and anti?ammonia?nitrite stress ability of oriental river prawn ( Macrobrachium nipponense) , and to discuss the suitable dietary LNA content. LNA was added to the diets to formulate six isonitrogenous and isolipidic semipu?rified diets containing 0 (L0, control), 0.5% (L0.5), 1.0% (L1.0), 1.5% (L1.5), 2.0% (L2.0) and 2.5% ( L2.5) LNA, respectively. Each diets fed 5 tanks ( replicates) with 50 prawns per tank. After 8 weeks of feeding, ten prawns from each tank were exposed to ammonia nitrogen ( total ammonia nitrogen concentra?tion in water was 36.6 mg/L) for 24 h. The results showed as follows: with the dietary LNA content increas?ing, the specific growth rate, weight gain rate and survival rate of prawns were increased firstly and then de?creased, but the differences were not significant among all groups ( P>0.05) . The contents of LNA in hepato?pancreas and muscle were all increased with the dietary LNA content increasing. The superoxide dismutase ( SOD) , glutathione peroxidase ( GSH?Px) activities and total antioxidant capacity ( T?AOC) in hepatopancre?as basically showed a trend of first increasing and then decreasing with the dietary LNA content increasing, and all of them reached the highest values in L1.0 group. The hepatopancreas malondialdehyde ( MDA) content in L0.5, L1.0, L1.5, L2.0 and L2.5 groups was significantly lower than that in L0 group ( P<0.05) . The prawn fed the diet with 1.0% LNA showed the highest hepatopancreas acid phosphatase ( ACP) , however, there was no significant difference between L1.0 and L1.5 groups ( P>0.05) . Hepatopancreas lysozyme ( LYZ) activity increased at first and then decreased with the dietary LNA content increasing, and it reached the highest activity in L1.5 group which was significantly higher than that in other groups ( P<0.05) . After 24 h ammonia?nitrite stress, hepatopancreas MDA content in L0.5, L1.5, L2.0 and L2.5 groups was significantly lower than that in L0 group ( P<0.05) , and the L1.5 group had the lowest MDA content which was significantly lower than that in other groups (P<0.05); hepatopancreas SOD activity and T?AOC showed a trend of first increasing and then decreasing with the dietary LNA content increasing, and them reached the highest values in L1.5 and L1.0 groups, respectively; hepatopancreas GSH?Px activity reached the highest value in L0 group, however, there was no significant difference between L0 and L1.0 groups ( P>0.05) . Taking hepatopancreas SOD activity as the indicator, the requirement of LNA for oriental river prawn was 1.19% according to quadratic regression a?nalysis. As a consequence of the above, the suitable dietary LNA content (1.0% to 1.5%) can improve the growth, antioxidant capacity, non?specific immunity, and can relax the negative effect caused by anti?ammo?nia?nitrite stress of oriental river prawn.