肽聚糖制剂对南美白对虾体液免疫因子的影响

Effects of peptidoglycan(PG) preparation on humoral immune factors of Litopenaeus vannamei

按一定梯度配制5种含不同水平肽聚糖制剂的饲料,投喂南美白对虾(Litopenaeusvannamei),35d后取实验对虾血样,用于测定血清中酚氧化酶活力、磷酸酶活力、溶菌活力及超氧化物歧化酶活力。结果显示,饲料中肽聚糖质量分数为500×10-6的实验组,对虾血清中酚氧化酶活力最高,肽聚糖质量分数为2500×10-6的实验组,对虾血清中酸性磷酸酶与碱性磷酸酶活力最高,肽聚糖对对虾的血清溶菌活力影响不明显(P>0.05)。由此表明饲料中添加适量(质量分数500×10-6左右)的肽聚糖制剂可使对虾体液免疫因子总体活力达到较高水平,饲料中肽聚糖制剂含量过高对对虾非特异免疫力的作用效果反而不佳。南美白对虾血清中酚氧化酶活力对饲料中肽聚糖含量变化较敏感,可作为肽聚糖使用效果的评价指标之一。

The American white shrimp Litopenaeus vannamei were collected from a culture farm in Qingdao at the body length (5.5±0.6) cm. Tested by nucleic probe, the shrimp were proved healthy without white spot syndrome virus (WSSV). Six added levels of peptidoglycan (PG) were designed which were mixed with the raw diets. The period was 35 d. The added levels of PG were 20, 100, 500, 2 500 mg (crude PG)/kg (raw diets) and 10 mg (refined diets)/kg(raw diets) and control (raw diets). The data indicated that in the group of PG added level at 500 mg/kg the activity of PO was the highest (P<0.05). Both activities of ALP and ACP in the group of 2 500 mg/kg were the highest (P<0.05). Neither activities of SOD nor lysozyme in the serum of shrimp from all test groups was significant higher than those in control (P>0.05). The results proved that an adequate added level of PG (e.g. 500 mg/kg) could increase the activities of the immune factors in shrimp to a high level, but the higher added level would not have good effect on the non-specific immunity in shrimp. The potential possibility for PG used in shrimp culture is to improve the immunity against disease and the optimum added level of PG in the diet is about 500 mg( crude PG)/kg (raw diets).