饲料中添加甘氨酸可提高大黄鱼(Larimichthys crocea)的抗氧化和抗应激能力

Dietary Glycine Improved the Capacity of Anti-Oxidation and Anti-Stress of Large Yellow Croaker(Larimichthys crocea)

为研究饲料甘氨酸对大黄鱼(Larimichthys crocea)抗氧化和抗应激反应的影响,将初始体重为(130.35±8.37)g的大黄鱼随机分成6组,每组3个重复,每个重复(网箱)50尾鱼。在基础饲料中分别添加不同梯度的甘氨酸(0、0.6%、1.2%、2.4%、4.8%和6.0%),配制出甘氨酸实测含量分别为(1.58%、2.15%、2.75%、3.96%、6.33%和7.51%)的6种实验饲料。经过30 d养殖后,对大黄鱼进行拖网应激实验。结果表明,养殖实验结束后,饲料处理未对大黄鱼的存活和体成分产生显著影响。肝脏总抗氧化能力在饲料甘氨酸含量为2.75%时达到最大值,而丙二醛的含量在甘氨酸含量为3.96%时达到最小值,但与2.75%组无显著差异(P>0.05)。以肝脏总抗氧化能力为评价指标,根据二次曲线回归模型得出大黄鱼饲料中甘氨酸的适宜含量为3.57%。血清谷草转氨酶和谷丙转氨酶的活性均在饲料甘氨酸含量为2.75%时呈现最小值(P<0.05)。在拖网应激前,饲料甘氨酸含量为2.75%时,大黄鱼血清皮质醇的含量最高。在拖网应激后,该处理的大黄鱼血清皮质醇的变化幅度最小,而此时的血糖维持在较高水平。综合考虑大黄鱼的抗氧化和抗应激能力,本研究推荐大黄鱼饲料中甘氨酸的适宜含量为2.75%–3.57%。

Large yellow croaker Larimichthys crocea is one of the most successful marine fish culture operations in terms of the number of juveniles produced and commercial size fish production annually in China. The production of this farmed species was more than 120000 metric tons in 2014 in China. However, large yellow croaker was often encountered with many stress situations, such as net cage changing, typhoon and water temperature oscillations during the grown-up farming. Generally, these could result in the decreases of feed utilization, anti-diseases ability and growth, even causing great economy losses. So, it is important to improve the anti-stress ability of large yellow croaker. The purpose of this study was to investigate the effects of dietary glycine on anti-oxidative and anti-stress responses of large yellow croaker （initial body weight 130.35±8.37 g）. There were 6 experimental diets containing graded levels of glycine （1.58%, 2.15%, 2.75%, 3.96%, 6.33% and 7.51%） with different levels of glycine supplementation （0, 0.6%, 1.2%, 2.4%, 4.8% and 6.0%）. After a 30 d feeding trial, the experimental animals were challenged with a 30 s trawl stress for three times. The results showed that the survival and body compositions of large yellow croaker had no significant differences among all the treatments （P〉0.05）. The significant highest value of the total anti-oxidative capacity in liver was found in the treatment with 2.75% dietary glycine. The lowest value of the malondialdehyde in liver was found in the treatment with 3.96% dietary glycine. However, this value of malondialdehyde did not significantly differ from that in the treatment with 2.75% dietary glycine （P〉0.05）. On the basis of hepatic total anti-oxidative capacity, using the second-order regression analysis, the most reasonable dietary glycine content for large yellow croaker was estimated to be 3.57%. Both the glutamic-oxaloacetic transaminase and the glutamic -pyruvic transaminase activities in serum had the lowest value in the treatment with 2.75% dietary glycine （P〈0.05）. Before the trawl stress, treatment with 2.75% dietary glycine resulted in the highest concentration of cortisol in serum （P〈0.05）. After the trawl stress, the serum cortisol concentration in this group kept little change. Meanwhile, the glucose concentration in serum kept at a relative higher level. In conclusion, for the purpose of improving the capacities of anti-stress in large yellow croaker, while had no significant negative effects on the survival and liver health, 2.75%–3.57% of dietary glycine were recommended for large yellow croaker.