Dietary zinc requirements and its effect on immune function in juvenile hybrid tilapia (Oreochromis niloticus x O. aureus) and juvenile grass prawn (Penaeus monodon)

• Main Authors: Chiang lee-chun, 江麗君
• Other Authors: 蕭錫延
• Format: Others
• Language: zh-TW
• Published: 2003
• Online Access: http://ndltd.ncl.edu.tw/handle/63175661368579406170

碩士 === 國立海洋大學 === 食品科學系碩士在職專班 === 91 === Abstract The study was to estimate the optimum dietary zinc requirements of juvenile hybrid tilapia (Oreochromis niloticus ´ O. aureus) and grass prawn (Penaeus monodon) and its effect on immume function. In Experiment I, purified diets with 8 levels (0, 5, 10, 20, 30, 40, 50, 100 mg/kg diet) of supplemental zinc were each fed to triplicate groups of tilapia (mean initial body weight 0.55 ± 0.01 g) for 8 weeks. Results indicated that no significant differences (P＞0.05) in weight gain (WG), feed efficiency (FE), protein efficiency ratio (PER), hepatosomatic index (HSI) and survival were observed among the dietary treatments. Fish fed diets supplemented with ≧5 mg Zn/kg had higher whole body, serum, bone and scale zinc concentrations than fish fed the unsupplemented control diet. Serum alkaline phosphatase activity was highest in fish fed diets supplemented with ≧30 mg Zn/kg, followed by 5 - 20 mg Zn/kg groups, and lowest in fish fed the unsupplemented control diet. No differences in serum superoxide dismutase (SOD), lysozyme and alternative complement (ACH50) activities were observed among the dietary treatments. Analysis by linear regression of whole body zinc retention and by broken-line regression of the serum zinc concentraction and alkaline phosphatase activity of the fish indicated that the optimum dietary zinc concentration in tilapia is approximately 25 - 30 mg Zn/kg diet. In Experiment II, purified diets with 8 levels (0, 10, 20, 30, 40, 50, 80, 120 mg/kg diet) of supplemental zinc were each fed to triplicate groups of P. monodon (mean initial body weight 0.44 ± 0.01 g) for 8 weeks. Results indicated that shrimp fed the zinc unsupplemented control diet had lower WG, FE and PER than shrimp fed diets supplemented with 30 - 40 mg Zn/kg diet. Shrimp fed diets supplemented with ≧50 mg Zn/kg had higher hepatic zinc concentration than shrimp fed the unsupplemented control diet. Shrimp fed diets supplemented with 30 - 40 mg Zn/kg diet had higher total haemocyte count than shrimp fed diets with ≦20 mg Zn/kg. Shrimp fed diets supplemented with 30 - 40 mg Zn/kg diet had higher superoxide anion than shrimp fed diets with ≦20 mg Zn/kg and ≧80 mg Zn/kg. Shrimp fed diets supplemented with ≧30 mg Zn/kg had higher phenoloxidase activity than shrimp fed diets with ≦20 mg Zn/kg. Analysis of the WG, whole body zinc retention and superoxide anion by broken-line regression indicate that the optimum dietary zinc requirement for P. monodom is approximately 32 - 41 mg Zn/kg diet.