The present study was conducted to investigate the effects of supplementation of yeast autolysate (YA) in practical diet on growth performance, immunity and disease resistance of Pacific white shrimp Litopenaeus vannamei. Four isonitrogenous and isolipidic practical diets were formulated. The relatively high fish meal control diet contained 25% of fish meal without YA supplementation (E1). The other control diet contained 20% of fish meal without YA (E2). Based on the E2, 1% of YA (E3) and 2% of YA (E4) were supplemented, respectively. The shrimp (initial weight: 0.30 ± 0.02 g) were fed with four experimental diets for 8 weeks, and then challenged with Vibrio parahaemolyticus. The results showed that no significant difference in survival rate (SR) and feed intake (FI) were observed among these groups. The weight gain rate (WGR) in group E1 were not significantly different with that of E3 and E4. The feed conversion ratio (FCR) in group E4 was lower than that of group E2, and group E4 had the highest protein efficiency ratio (PER). The total haemocyte counts (THC) and lysozyme activities in group E3 and group E4 were significantly higher than these of other groups. Group E3 had the significantly highest respiratory burst (RB). After V. parahaemolyticus administration, group E3 and group E4 had significantly lower cumulative mortalities than group E1. In conclusion, compared with the 25% fish meal in diet without YA supplementation (E1), 20% fish meal in diet without YA supplementation (E2) had significant lower growth rate. Compared with the 20% fish meal in diet without YA supplementation (E2), supplementation of 1% of YA in diet improved the growth rate, immune response and resistance of L. vannamei to the challenge with V. parahaemolyticus.

中文翻译：

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实际日粮中酵母自溶物对南美白对虾生长性能、免疫反应和抗病能力的影响

本研究旨在研究在实际日粮中添加酵母自溶物 (YA) 对南美白对虾生长性能、免疫力和抗病能力的影响。配制了四种异氮和异脂的实用日粮。相对较高的鱼粉对照日粮含有 25% 的鱼粉，未添加 YA（E1）。其他对照饮食含有 20% 的鱼粉，不含 YA (E2)。在E2的基础上，分别补充了1%的YA（E3）和2%的YA（E4）。虾（初始重量：0.30 ± 0.02 g）用四种实验饲料喂养 8 周，然后用副溶血性弧菌进行攻击。结果表明，在这些组中未观察到存活率（SR）和采食量（FI）的显着差异。E1组体重增加率（WGR）与E3和E4组无显着差异。E4组饲料转化率（FCR）低于E2组，E4组蛋白效率比（PER）最高。E3组和E4组的总血细胞计数（THC）和溶菌酶活性显着高于其他组。E3 组的呼吸爆发 (RB) 显着最高。副溶血性弧菌给药后，E3 组和 E4 组的累积死亡率显着低于 E1 组。总之，与未添加 YA 的日粮中 25% 的鱼粉（E1）相比，未添加 YA 的日粮中的 20% 鱼粉（E2）的增长率显着较低。与未添加 YA 的日粮中 20% 的鱼粉（E2）相比，