Effects of different durations of fasting/re-feeding bouts on growth, biochemical and histological changes in the digestive tract of Gansu golden trout (Oncorhynchus mykiss)

Abstract

This study was conducted to explore the outcomes of starvation/re-feeding techniques on growth performance, liver antioxidant activities, and histological changes of the gastrointestinal organs of Gansu golden trout. A total of 225 juveniles were divided into 5 treatment groups; the control group (N<sub>0</sub>) was routinely fed every day while the other groups (N<sub>7</sub>, N<sub>14</sub>, N<sub>21</sub>, and N<sub>28</sub>) were starved for 7, 14, 21, and 28 days, respectively and after the starvation session, each group was re-fed for 28 days. Compensatory growth was statistically recorded in N<sub>14</sub>. Weight gain rate and feeding ratio were the highest in the N<sub>14</sub> group, while specific growth rate and feeding conversion ratio showed significant increases in the fish groups exposed to longer starvation periods. Liver antioxidant activities showed a significant increase and decrease in malondialdehyde and superoxide dismutase levels in N<sub>21</sub> and N<sub>28</sub>, respectively, which returned to normal levels after re-feeding. Stomach, intestine, and liver showed histological alterations in all groups and the severity was correlated with the fasting periods. Those changes were restored to a certain degree after feeding was resumed. The compensation by group N<sub>14</sub> presents potential for economic usefulness of the fasting/re-feeding strategy in Gansu golden trout.