饥饿对草鱼血清游离氨基酸的影响

Effects of Fast on the Contents of Free Amino Acids in Serum of Grass Carp(Ctenopharyngodon idella)

将池塘捕获的体重(1.70±0.80)kg的草鱼(Ctenopharyngodon idella)饲养在室内水族箱内,分别测定了空腹(禁食1 d,26样本)、饥饿15 d(15样本)、饥饿30 d(15样本)的草鱼血清游离氨基酸含量。结果显示:草鱼血清游离氨基酸总量基本恒定,空腹、饥饿15 d和饥饿30 d的氨基酸总量无显著差异;处于饥饿状态的草鱼血清游离必需氨基酸总量极显著地高于空腹状态,非必需氨基酸总量极显著地低于空腹状态;血清赖氨酸、缬氨酸、异亮氨酸、亮氨酸和胱氨酸含量因饥饿显著升高,而组氨酸、苯丙氨酸、天冬氨酸、丝氨酸、谷氨酸和酪氨酸因饥饿显著降低;饥饿15 d和饥饿30 d各氨基酸含量均未见差异。草鱼血清游离氨基酸含量在正常摄食情况下主要受饲料蛋白质影响,处于饥饿状态下主要来源于肌体蛋白质的分解,比较正常摄食后和饥饿状态下血清游离氨基酸的组成可评价饲料蛋白质的质量。

The grass carp（ Ctenopharyngodon idella） weighing （ 1.70 ± 0. 8 ） kg were reared in aquarium without feeding after being caught from fish pool. The contents of free amino acids in serum were determined after being fasted for 1 day （26 samples）, 15 days （15 samples） and 30 days （15 samples）. The results showed that the contents of total free amino acids in serum were not affected significantly by fast time（ 1, 15 or 30 days）. The content of total essential amino acids was significantly （P 〈 0, 01 ） higher but the value of total dispensable amino acids was significantly（P 〈 0. 01 ） lower on days 15 and days 30 than those on day 1. The level of lysine, valine, isoleucine, leucine or cystine was significantly lower but the value of histidine, phenylalanine, aspartic acid, serine, glutamic acid or tyrosine was significantly higher on day 1 than that on days 15 and days 30. No significant difference was found on the content of free amino acids between days 15 and days 30. The contents of free amino acids in serum of the fish were affected mainly by the dietary protein in normal feeding condition, whereas by the decomposition of proteins in tissue in fast condition, therefore the protein quality in diet could be evaluated by comparing the pattern of free amino acid in grass carp serum in normal feeding condition with that in fast period.