Temperature and dietary carbohydrate level effects on performance and metabolic utilisation of diets in European sea bass (Dicentrarchus labrax) juveniles
Introduction
European sea bass (Dicentrarchus labrax) is one of the most important aquaculture species in the Mediterranean countries. An adequate knowledge of its nutritional requirements and nutrient utilisation is of utmost importance for a sustainable production, as it will allow formulation of high quality diets that promote optimum growth and diet utilisation, while minimising losses to the environment (Oliva-Teles, 2000).
European sea bass has high protein requirement (Peres and Oliva-Teles, 1999). This has a negative impact on dietary costs as protein is the most expensive single nutrient in formulated diets. High dietary protein levels are also associated to negative environmental impacts due to potential high nitrogenous losses. Therefore, reducing dietary protein levels and maximizing protein utilisation by the animals is prioritary both from an economical and an environmental perspective. As a result, great deal of research has been conducted on the protein-sparing potential of lipids and carbohydrates in fish diets (Oliva-Teles, 2000, Watanabe, 2002). Carbohydrates are the least expensive energy source; therefore its inclusion in the diets allows a reduction of feed costs. However, in nature fish have limited access to carbohydrates and are better adapted both at digestive and metabolic levels, to utilise proteins and lipids than carbohydrates as energy sources (Wilson, 1994). The protein-sparing effect of lipids is well demonstrated in several fish species (Watanabe, 1982, Sargent and Tacon, 1999) but that of carbohydrates is still controversial (Wilson, 1994, Hemre et al., 2002, Stone, 2003). The recommended inclusion level of digestible carbohydrates in fish diets is species-dependent. In general, carnivorous species, including salmonids and most marine fish, tolerate lower dietary carbohydrate levels than herbivorous or omnivorous species (Wilson, 1994). Besides dietary inclusion level, the efficiency of dietary carbohydrate utilisation by fish has been associated to factors such as botanical origin, complexity of the molecule, and technological treatments applied (Wilson, 1994, Stone, 2003, Krogdahl et al., 2005).
Data on carbohydrate utilisation by European sea bass is discordant. A protein-sparing effect of pregelatinized starch incorporated in the diets at 15% was observed by Hidalgo and Alliot (1988). Lanari et al. (1999) recommended that the dietary incorporation of digestible carbohydrates such as dextrin or gelatinized starch should not exceed 20% of the diet. Gouveia et al. (1995) concluded that either raw or gelatinized starch could be included in the diets at 25% without significant effects on growth performance and feed utilisation efficiency. Concurrently, Enes et al. (2006) reported that neither level (10 or 20%) nor nature (raw or waxy) of starch had measurable effects on growth performance and feed utilisation in juveniles. In contrast, Dias et al. (1998) reported improved growth and feed utilisation of juveniles fed gelatinized starch as compared to raw starch at both dietary inclusion levels tested (11% and 23%). Finally, according to Peres and Oliva-Teles (2002) performance of juveniles was better when fed a mixture (12.5% raw starch plus 12.5% gelatinized starch) than either 25% gelatinized or 25% raw starch.
Data on the effect of temperature on carbohydrate utilisation by fish is even scarcer. In carp, increasing water temperature improved starch digestibility (Médale et al., 1999) while enzyme activities were higher at lower temperatures, denoting thermal compensation for acclimation to low temperature (Shikata et al., 1995). In rainbow trout, starch digestibility and utilisation as energy source improved at higher temperature (Médale et al., 1991). Growth and protein retention in rainbow trout were not affected by dietary carbohydrate: lipid ratio at 8 °C, but at 18 °C weight gain tended to be higher with the lower carbohydrate: lipid ratio (Brauge et al., 1995). In European sea bass, besides growth performance, temperature was shown to affect feed efficiency, protein utilisation, body composition and glycolytic, lipogenic and gluconeogenic capacities (Peres and Oliva-Teles, 1999, Person-Le Ruyet et al., 2004, Enes et al., 2006).
Therefore, the aim of this study was to evaluate, in a pair-feeding experiment, the effect of three dietary inclusion levels (10%, 20% and 30%) of pregelatinized starch on growth performance, nutrient utilisation and whole-body composition of European sea bass juveniles reared at two water temperatures (18 °C and 25 °C). In order to obtain further information on metabolic utilisation of the diets, activities of selected hepatic key-enzymes of intermediary metabolism were also measured.
Section snippets
Materials and methods
The experiment was carried out at the experimental facilities of the Marine Zoology Station of Faculty of Sciences, at Porto University, and consisted of a growth trial and a digestibility trial.
Results
During the trial one tank was lost due to a technical incident. In the others tanks mortality ranged from 1.4% to 4.2% and was not different among groups. Final body weight, weight gain and specific growth rate were higher in fish reared at 25 °C and within each temperature were not affected by diet composition (Table 2). Feed intake was also higher at 25 °C. As fish were fed according to a pair-feeding scheme, feed intake was necessarily different among groups. Feed efficiency was higher at
Discussion
Carnivorous fish like European sea bass are considered not to digest carbohydrates very efficiently (Wilson, 1994, Krogdahl et al., 2005). It is also known that technological treatments, such as gelatinization may improve starch digestibility and, consequently, digestibility of energy (Peres and Oliva-Teles, 2002). Moreover, dietary starch level may negatively affect carbohydrate digestibility and may also interact with the digestibility of other dietary constituents (Kaushik and Medale, 1994,
Acknowledgements
This work was partially supported by Fundação para a Ciência e a Tecnologia, Portugal (project POCI-CVT-57695-2004).
References (40)
- et al.
Glucose-6-phosphate dehydrogenase from Dicentrarchus labrax liver: kinetic mechanism and kinetics of NADPH inhibition
Biochim. Biophys. Acta
(1988) A rapid and sensitive method for the quantification of microgram quantities of protein utilizing the principle of protein-dye binding
Anal. Biochem.
(1976)- et al.
Effect of dietary carbohydrate levels on growth, body composition and glycaemia in rainbow trout, Oncorhynchus mykiss, reared in seawater
Aquaculture
(1994) - et al.
Bioenergetics of salmonid fishes: energy intake, expenditure and productivity
Comp. Biochem. Physiol.
(1982) - et al.
Glycemic and glycosuric responses in white sturgeon (Acipenser transmontanus) after oral administration of simple and complex carbohydrates
Aquaculture
(2001) - et al.
Regulation of hepatic lipogenesis by dietary protein/energy in juvenile European seabass (Dicentrarchus labrax)
Aquaculture
(1998) - et al.
Effect of normal and waxy maize starch on growth, food utilization and hepatic glucose metabolism in European sea bass (Dicentrarchus labrax) juveniles
Comp. Biochem. Physiol., A
(2006) - et al.
Influence of water temperature on protein requirement and protein utilization in juvenile sea bass, Dicentrarchus labrax
Aquaculture
(1988) - et al.
Influence of water temperature on food intake, food efficiency and gross composition of juvenile sea bass, Dicentrarchus labrax
Aquaculture.
(1987) - et al.
Effect of digestible energy on nitrogen and energy balance in rainbow trout
Aquaculture
(1985)
Energy requirements, utilization and dietary supply to salmonids
Aquaculture
Low protein intake is associated with reduced hepatic gluconeogenic enzyme expression in rainbow trout (Oncorhynchus mykiss)
J. Nutr.
The effects of dietary fat and NFE levels on growing European sea bass (Dicentrarchus labrax L.). Growth rate, body and fillet composition, carcass traits and nutrient retention efficiency
Aquaculture
Effects of temperature on growth and metabolism in a Mediterranean population of European sea bass, Dicentrarchus labrax
Aquaculture
Determination of starch with glucoamylase
A glucokinase-like enzyme in the liver of Atlantic salmon (Salmo salar)
Comp. Biochem. Physiol., B
Lipid nutrition in fish
Comp. Biochem. Physiol.
Utilization of dietary carbohydrate by fish
Aquaculture
Etude de l'apport calorique et du rapport calorico-azoté dans l'alimentation du bar, Dicentrarchus labrax
The partial substitution of digestible protein with gelatinized starch as an energy source reduces susceptibility to lipid oxidation in rainbow trout (Oncorhynchus mykiss) and sea bass (Dicentrarchus labrax) muscle
J. Anim. Sci.
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