The impact of varying feeding regimes on oxygen consumption and excretion of carbon dioxide and nitrogen in post-smolt Atlantic salmon Salmo salar L.

Abstract

Oxygen consumption, carbon dioxide excretion and nitrogen excretion from 2 kg Atlantic salmon Salmo salar L. were studied at land‐based outdoor tanks, throughout a 10 day period. Fish were fed six feed rations (0 [fasting fish], 0.15, 0.30, 0.45, 0.60 and 0.75% BW day‐1) of commercially extruded dry feed at two provision regimes: between 07.00‐09.00 h and 19.00–21.00 h (periodic feeding); and between 07.00‐21.00 h (continuous feeding). Fish were acclimatized to the feeding regime for 5 days prior to the start of the experiment. From days 5 to 10 of the study, oxygen consumption was measured automatically every 15 min. During day 10, carbon dioxide excretion, ammonia and urea excretion were measured hourly throughout a 24 h period. During the experiment, the water temperature and salinity were 8.5C and 33.5 ppt, respectively. Significant linear relationships between feed ration and metabolic rates were evident. Increased feed ration influenced oxygen consumption, carbon dioxide excretion, ammonia and urea excretion, ammonia quotient and the respiration quotient, proportionally. The two feed provision regimes caused the establishment of different daily rhythms in metabolic excretion. Only small differences in total daily excretion were however recorded for each feed ration. Ammonia and respiratory quotient results clearly showed that fish became more dependent on fat oxidation as an energy source, when feed was restricted.

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“…Based on the pre-feeding AQ (0.09-0.11), we estimated that 27-33% of the oxygen consumed was used for oxidizing protein in the prefeeding snakehead (Table 1). This is similar to the value for southern catfish in a comparable warm water region (Luo et al, 2009), but higher than those of many other cold water species, including rainbow trout, Atlantic salmon (Salmo salar), Arctic charr (Salvelinus alpinus), and Eurasian perch (Perca fluviatilis) (Lauff and Wood, 1996;Forsberg, 1997;Lyytikäinen and Jobling, 1998;Zakęs et al, 2003). Snakehead showed increasing TAN and AQ values (Clarke and Thomas, 1997;Owen et al, 1998;Peck et al, 2003;Also and Wood, 1997;Lyytikäinen and Jobling, 1998;Luo and Xie, 2009).…”

Size-related oxygen consumption and ammonia excretion of Eurasian perch (Perca fluviatilis L.) reared in a recirculating system

“…Expressed as percentages, there is a difference of 6.8%. This discrepancy is probably due to the high feeding rate in our study (1.7–1.2% of BW), as was shown in a study using Atlantic salmon (Forsberg 1997). Thus, the metabolic activity of fish in our study was higher.…”

“…Thus, the metabolic activity of fish in our study was higher. Other factors that have been shown to influence the mean daily OC in fish include temperature (Zakęś & Karpinski 1999; Zakęś et al 2003; Díaz et al 2007), management of feeding or feeding rate (Forsberg 1997; Zakęś & Demska‐Zakęś 2002; Zakęś et al 2006) and anaesthesia (Hoskonen & Pirhonen 2004). Our data imply that 1 kg of food distributed in a perch‐rearing system represents the OC from 173.1 g (48 g fish) to 205.8 g (273 g fish) including basal OC.…”

“…Diurnal fluctuation for OC of fish has been described previously (Forsberg 1997; Zakęś & Demska‐Zakęś 2002; Zakęś et al 2003). Oxygen consumption has generally been reported to increase rapidly a short time after feeding as a consequence of feeding management (specific dynamic action, feeding frequency and daily feed ratio) and then decrease gradually to the basal level.…”

Migration model of post‐smolt Atlantic salmon (Salmo salar) in the Gulf of Maine

“…Fish expending energy on swimming fast, may have less time and energy to forage, thereby lowering their growth rate. As foraging rate and food intake decreases, fish are more dependent on fat oxidation to maintain weight (Forsberg, ). Whether this trade‐off is advantageous or not, depends on many factors, such as predator–prey fields.…”