Effects of different levels of Yucca schidigera extract on the growth and nonspecific immunity of Pacific white shrimp (Litopenaeus vannamei) and on culture water quality

Abstract

Abstract A total of 6000 shrimp (initial body weight of 0.82 ± 0.02 g) were randomly distributed into twelve concrete pools (4.5 m × 3.5 m × 0.5 m) with 500 shrimp per pool and 3 pools per diet, respectively. Four kinds of isonitrogen and isoenergetic diets were formulated with 0, 0.1%, 0.2% and 0.3% Yucca schidigera extract (YSE), respectively. The experiment lasted 100 d. The results showed as follows: when supplemented with 0.2% dietary YSE, the shrimp weight gain rate significantly increased (p 0.05). Addition of 0.2% dietary YSE significantly increased the shrimp serum protein content, as well as the activities of acid phosphatase, alkaline phosphatase, nitric oxide synthase, glutamic–pyruvic transaminase, phenol oxidase, and hepatopancreas proteases (p 0.05). In the late culture period (5th week to 14th week) the total amount of ammonia-nitrogen, nitrite-nitrogen, nitrate-nitrogen, and reactive phosphorus in the culture water significantly decreased (p