Effects of fasting on metabolic and immunological responses of common carp ( Cyprinus carpio ) to a further acute stress

Abstract

Common carp were fasted for 0, 3 and 14 days prior to exposure to a 2‐hr crowding stress. Serum cortisol, glucose, lactate, T4, T3, serum alternative complement (ACH50), lysozyme, total immunoglobulin (Ig) and blood WBC were determined before and 0, 6 and 24 hr after the crowding stress. Three days of fasting led to a significant decrease in serum levels of lactate and thyroid hormones. Fourteen days of fasting led to initiation of physiological process to maintain serum glucose by increase in serum cortisol level and lactate utilization. These fish had lower levels of thyroid hormones suggesting suppression of basal metabolism. The fish also had lower WBC and serum lysozyme and total Ig levels indicating immunosuppression. After the crowding stress, the fish fasted for 3 days had significantly lower lactate, thyroid hormones and total Ig levels. The fish fasted for 14 days had higher cortisol but lower glucose and thyroid hormones levels suggesting impairment in metabolic responses to the crowding stress. Immunological and health indicators including WBC, and ACH50, lysozyme and total Ig of these fish were significantly lower than the other groups after the crowding stress. Overall, the results show that a 14‐day fasting leads to stress responses, reduction in metabolism and immunosuppression. Moreover, 14 days of fasting lead to greater cortisol response to a further crowding stress, which induces marked immunosuppression and fallen welfare.

Dietary licorice ( Glycyrrhiza glabra ) improves growth, lipid metabolism, antioxidant and immune responses, and resistance to crowding stress in common carp, Cyprinus carpio

“…The elevated serum proteins and ACH50 activity may be associated with the health of the liver (the site for many protein syntheses), and dietary licorice was reported to be hepatoprotective in fish (Elabd et al., 2016, 2017; Yin et al., 2011). Also, the immunostimulant mechanisms of licorice may be attributed to the presence of immunoregulative compounds such as glycyrrhizin, glycyrrhetinic acid, licochalcone A, glycyrrhizic acid, polysaccharides and saponins (Nassiri Asl & Hosseinzadeh, 2008) and increased fish welfare and health by dietary licorice supplementation (see below), as it has been shown that stress conditions impact fish health and induce immunosuppression in fish (Hoseini et al., 2019; Naderi et al., 2019; Tort, 2011).…”

“…Also, the extract of licorice could improve the resistance of fish to stress and infection (Wang et al., 2007). Improved antioxidant activities and suppressed cortisol levels can explain enhanced immune functions in juvenile common carp fed 20 and 30 g/kg dietary licorice, as there are strong relationships between immune function and antioxidant defence (Naderi et al., 2019) as well as stress level (Hoseini et al., 2019; Tort, 2011; Yousefi et al., 2020).…”

“…as it has been shown that stress conditions impact fish health and induce immunosuppression in fish (Hoseini et al, 2019;Naderi et al, 2019;Tort, 2011).…”

Fasting combined with long catch duration modifies the physio‐metabolic response and flesh quality of rainbow trout

“…Similarly, in aquaculture, fasting carp for 14 days makes them more susceptible to crowding stress, although short fasting times (i.e. 3 days) have significant effects on fish health (Hoseini, Abtahi, & Yousefi, ). However, little is known about the combined effects of fasting and prolonged catch duration on the welfare or product quality of farmed fish.…”

“…Crowding depletes tissue energy stores, increases lactate and causes osmoregulatory imbalance in fish (Cooke & Suski, 2005) and increases cortisol and haematocrit levels (Merkin, Roth, Gjerstad, Dahl-Paulsen, & Nortvedt, 2010). 3 days) have significant effects on fish health (Hoseini, Abtahi, & Yousefi, 2019). Similarly, in aquaculture, fasting carp for 14 days makes them more susceptible to crowding stress, although short fasting times (i.e.…”