Effects of inosine 5′-monophosphate supplementation in high fishmeal and high soybean diets on growth, immune-related gene expression in gibel carp (Carassius auratus gibelio var. CAS Ⅲ), and its challenge against Aeromonas hydrophila infection

The present study was conducted to evaluate dietary inosine 5′-monophosphate (5′-IMP) on growth, immune genes expression and disease resistance against Aeromonas hydrophila in juvenile gibel carp (Carassius auratus gibelio var. CAS Ⅲ) (initial body weight: 7.48 g). Six diets were formulated containing exogenous 5′-IMP at three gradient levels (0, 0.1% and 0.2%) in the high dietary fishmeal group (15% fishmeal: D1, D2, D3) and in the high dietary soybean meal group (33% soybean meal: D4, D5, D6). Each diet was randomly allotted to triplicate tanks in a recirculating system. After the feeding trial, fish were exposed to Aeromonas hydrophila challenge. Hematological and immunological responses were analyzed before and after challenge. The results indicated that feeding rate in all 5′-IMP supplemented treatments (D2, D3, D5 and D6) and daily growth coefficient in D5 and D6 were reduced compared with those of respective control treatments (D1 and D4) without 5′-IMP addition (P 0.05). Compared with the respective control treatment, in the high fishmeal group, plasma SOD and MPO were significantly elevated in D3 at the end of feeding trial (P