Starvation alters growth, stress metabolites and physiological responses in juvenile great sturgeon (Huso huso)

Abstract

A 4-week trial was conducted to investigate the influence of food deprivation on the growth, body composition, biochemical and hematological parameters in juvenile great sturgeon (Huso huso) as well as physiological responses to acute handling stress. Fish with an average weight of 78.27 ± 0.2 g (mean ± S.E) were assigned to two feeding regimes: fed (control) and starved groups. The final weight in the fed group (159.5 ± 1.8 g) was 2.5-fold higher than that of the starved group (63.9 ± 0.7 g). Other growth indices (e.g. condition factor, body weight increase, specific growth rate, hepatosomatic and viscerosomatic indices) in the starved group were significantly lower than those measured in the fed group. Plasma biochemical parameters (cholesterol, triacylglycerol, total protein, glucose, and lactate) and cortisol levels considerably declined after 4 weeks of starvation. Starvation had significant effects on the proximate composition of muscle and liver, and also resulted in a significant reduction in oxygen consumption. The structure of the liver was affected by starvation after 4 weeks, but no structural changes were observed in the mucosa of intestinal wall. At the termination of the rearing experiment, both groups were subjected to 60-s aerial emersion in a net and blood samples were collected at 0 (resting time), 1, 3, 6, 9, 12 and 24 h after handling. Although a noticeable rise in plasma cortisol occurred within 1 h in the fed group, it was almost constant in the starved group throughout the sampling times. The highest concentrations of plasma glucose were observed at 3 h (44.2 ± 0.5 mg dL−1) and 6 h (87.5 ± 7.1 mg dL−1) after handling in the starved and fed groups, respectively. Lactate levels were considerably higher in the fed group than those in the starved fish in most sampling times. Hemoglobin values increased significantly by 24 h post handling in both experimental groups. Lymphopenia and neutrophilia were also observed in the starved fish 9 h following 60 sec net handling. These findings suggest that nutritional status considerably influences energy storage and subsequent stress and metabolic responses, so that starvation mitigated the responses of great sturgeon to an acute handling stress.