Effects of dietary lactosucrose on the gene transcript profile in liver of grass carp ( C tenopharyngodon idella )

Grass carp ( C tenopharyngodon idella ) is a valuable aquacultural species in C hina, but it is highly vulnerable to infectious diseases, which consequently may cause tremendous economical loss. To reduce the risk of disease in the fish, antibiotics have been used in the fish diet, which in turn caused some negative effects on human health. In this study, we choose lactosucrose ( LS ) as antibiotic alternative added to the diet of the grass carp juveniles and then to evaluate the effects of 15 g Kg −1 LS in the diet on the gene transcript profiles. After the trial for 56 days, we observed that the weight gain rate, specific gain rate and feed conversion rate were increased by 14.2%, 9.2% and 10.1%, respectively, in the trial group compared with the control group. The gene expression levels in the liver tissues of grass carps were assayed using the zebrafish c DNA microarray technology and real‐time RT ‐ PCR . Comparing with the control group, 416 genes were identified, and among them, 266 genes were up‐regulated and 150 were down‐regulated on the trial group. Among the up‐regulated genes selected, most of them related to growth, immune reaction and sugar metabolism. Most of the down‐regulated genes are RAS oncogene family members, V ‐myc viral oncogene homologue and programmed cell death–related factors. The apparent regulation of gene expression stimulated by LS suggests that the potential application of the LS in improving the growth performance and immunity on the grass carps. Together, this study provides convincing data in support of the use of LS as an alternative dietary antibiotic in fish.