Metabolic responses to short starvation and re-feeding in rainbow trout (Oncorhynchus mykiss)

Abstract: A feeding study was conducted to determine the effect of short-term starvation periods and subsequent re-feeding on some morphological and physiological parameters of rainbow trout (Oncorhynchus mykiss) fingerlings. Two hundred and seventy trout fingerlings (mean ± SE, 17.5 ± 0.06 g) were randomly distributed in 15 circular fiberglass tanks. The fish were exposed to five different feeding regimes: control, fed twice daily for 60 days; T1, one day starvation and two days re-feeding (20 cycles); T2, one day starvation and four days re-feeding (12 cycles); T3, three days starvation and 12 days refeeding (four cycles), T4, four days starvation and 16 days re-feeding (three cycles). Blood samples were taken for biochemical analyses at the end of the experiment. The results indicated that plasma cortisol, glucose, total protein, cholesterol, albumin, low-density lipoprotein, uric acid, creatinine, high-density lipoprotein, alkaline phosphatase, and aspartate aminotransferase levels were not significantly different between the control and starved fish, but plasma triglyceride and glucose levels were significantly higher in the T4 group as compared to the control and other deprived groups. There were no significant differences in perivisceral fat index among the five groups. However, hepatosomatic index significantly decreased in the T3 group in comparison with other groups. The present study demonstrates that rainbow trout could tolerate short-term starvation periods and subsequent feeding without any significant health damage particularly regarding some morphological and physiological parameters.
Keywords: Starvation Re-feeding Physiological parameters Morphological parameters Rainbow trout In