Determination of the optimal dietary digestible energy (DE) level in fish diets requires information on energy requirements for maintenance (DEm) and utilisation for growth (kgDE). This study assessed 1) variability in DEm and kgDE across fish species; 2) how digestible protein (dPro), fat (dFat) and carbohydrates (dCarb) affect kgDE and 3) if these effects differ between fish species. We reviewed literature data from studies relating retained energy (RE) to DE, under optimal nutritional and environmental conditions. Across fish species, DEm ranged from 16 to 110 kJ/kg0.8/d and kgDE from 0.31 to 0.82. Within and across species, variability in kgDE correlated with the trophic level of fish, macronutrient composition of diets and composition of growth. For quantifying the impact of digestible nutrient composition on kgDE, RE was related to dPro, dFat and dCarb using multi-variate analysis. For Nile tilapia and rainbow trout, this was done by systematic analysis across studies undertaken at Wageningen University and INRA, respectively. For common carp and Asian seabass (barramundi), this relationship was estimated within one experiment in which contrasts in dPro, dFat and dCarb were created by varying dietary macronutrient content (in 4 diets) and applying 3 to 5 feeding levels, respectively. For Nile tilapia and common carp, all digestible nutrient intakes were linearly related to RE and the energy efficiency was lowest for dPro and highest for dFat. The relationship between dCarb and RE was curvilinear; for trout significantly and for barramundi with a strong tendency. The estimated relationships between RE and dPro, dFat and dCarb can be used to predict the net energy (NE) value of diets, but also for ingredients if the macronutrient digestibility is known. In conclusion, kgDE is dependent on the digestible nutrientcomposition, but the extent of these influences is species dependent.
|Number of pages||1|
|Publication status||Published - 7 Jun 2018|
|Event||18th International Symposium on Fish Nutrition and Feeding: 40 Years of Research in Fish Nutrition - Auditorio Alfredo Kraus, Las Palmas de Gran Canaria, Spain|
Duration: 3 Jun 2018 → 7 Jun 2018
|Conference||18th International Symposium on Fish Nutrition and Feeding|
|City||Las Palmas de Gran Canaria|
|Period||3/06/18 → 7/06/18|