Effect Of Nucleotide Supplemented In The Formulated Diets On Immune Function Of Penaeus Vanname

The article studies the effect of nucleotide in the formulated diets on immune function of Penaeus vannamei under normal states and pH, salinity and ammonia-nitrogen stress, measuring PO, PC, SOD, Na+-K+-ATPase, bacteriolytic, antibacterial activity and contents of O2-.The whole experiment is divided into two parts. The first part is to study the effect of nucleotide on the immune system of Penaeus vannamei. Among a series of dose of nucleotide (0.01%, 0.02%, 0.03%, 0.04%, 0.05% and 0.06%), index of immunity was measured at different stage. The result shows that nucleotide has positive effect on the immunity of Penaeus vannamei at normal states, which can hold for some time. Immune function of most tested groups reached the highest value at the day 14th. The index of low dose (0.01% and 0.02%) is higher than that of control group: the activity of PO was enhanced by 182% and 128%; the bacteriolytic activity was enhanced by 97.6% and 41.5%; antibacterial activity was enhanced by 37.4% and 6%; SOD activity was enhanced by 134.6% and 78.3%. According to the experiment results, we advise that a feasible does be 0.01% to 0.02% and nucleotide be fed after an interval.The second part is to study the effect of nucleotide on the immune function of Penaeus vannamei exposed to different pH, salinity and ammonia-nitrogen. Under pH stress, when the pH of water was 5.5, the PO, PC, antibacterial activity, SOD ascended without exception, and the immune index of nucleotide group were higher than those of control group. PO, PC, antibacterial activity, SOD of nucleotide group were 125%, 22%, 14%, 89% higher than that of the control group respectively. Na+-K+-ATPase, which of control group was higher than that of nucleotide group, increased too(P<0.05). Bacteriolytic activity decreased along with pH. When the pH of water was 10.5, the PO, PC, bacteriolytic activity, antibacterial activity, SOD andNa+-K+-ATPase ascended without exception. The O2 in muscle of Penaeus vannamei decreased under pH stress.PO, bacteriolytic activity, SOD and Na+-K+-ATPase activity increased after 24h salinity stress. And those of nucleotide group were enhanced significantly. PC of nucleotide group was sensitive to the salinity stress, which decreased significantly. But PC of control group held the level at 1.2% salinity. 02- of Penaeus vannamei changed according to the salinity. The antibacterial activity of nucleotide changed insignificantly when the salinity was changing, but which of basal diet enhanced significantly at the high salinity. Bacteriolytic activity was enhanced by dietary nucleotide at high salinity. Different immune index of Penaeus vannamei was changed by the ammonia-nitrogen of water. All of the PO, antibacterial activity, SOD and Na+-K+-ATPase activity of tested group were higher for the shrimps exposed to ammonia-nitrogen. The results show that dietary nucleotide can delay the harm to the shrimp and raise the immunity of the Penaeus vannamei. The O2 changed insignificantly. PC and bacteriolytic activity decreased. But the range of tested group was lower than that of control group.The study shows that the dose and time of dietary nucleotide has effect on the immune function of Penaeus vannamei. The additive nucleotide can not only enhance the immunity of Penaeus vannamei under stress, but also delay the harm to the shrimp and raise the resistibility to stress.