Energy efficiency of digestible protein, fat and carbohydrate utilisation for growth in rainbow trout and Nile tilapia

Abstract

Currently, energy evaluation of fish feeds is performed on a digestible energy basis. In contrast to net energy (NE) evaluation systems, digestible energy evaluation systems do not differentiate between the different types of digested nutrients regarding their potential for growth. The aim was to develop an NE evaluation for fish by estimating the energy efficiency of digestible nutrients (protein, fat and carbohydrates) and to assess whether these efficiencies differed between Nile tilapia and rainbow trout. Two data sets were constructed. The tilapia and rainbow data set contained, respectively, eight and nine experiments in which the digestibility of protein, fat and energy and the complete energy balances for twenty-three and forty-five diets was measured. The digestible protein (dCP), digestible fat (dFat) and digestible carbohydrate intakes (dCarb) were calculated. By multiple regression analysis, retained energy (RE) was related to dCP, dFat and dCarb. In tilapia, all digestible nutrients were linearly related to RE (P<0·001). In trout, RE was quadratically related to dCarb (P<0·01) and linearly to dCP and dFat (P<0·001). The NE formula was NE=11·5×dCP+35·8×dFAT+11·3×dCarb for tilapia and NE=13·5×dCP+33·0×dFAT+34·0×dCarb-3·64×(dCarb)2 for trout (NE in kJ/(kg0·8×d); dCP, dFat and dCarb in g/(kg0·8×d)). In tilapia, the energetic efficiency of dCP, dFat and dCarb was 49, 91 and 66 %, respectively, showing large similarity with pigs. Tilapia and trout had similar energy efficiencies of dCP (49 v. 57 %) and dFat (91 v. 84 %), but differed regarding dCarb.

Effect of dietary carbohydrate to lipid ratio on performance of Nile tilapia and enhancement of natural food in pond aquaculture

“…Effect of dietary carbohydrate to lipid ratio and feeding level on pond water quality used more efficiently than digested starch (Schrama, Haidar, Geurden, Heinsbroek, & Kaushik, 2018). However, in the current study this was not reflected in growth differences, which also might be due to differences in husbandry conditions between experiments.…”

“…However, comparing both experimental diets, the composition of the digestible energy coming from fats and carbohydrates differed strongly between both experimental diets. It has been shown recently in tilapia that digested fat is used more efficiently than digested starch (Schrama, Haidar, Geurden, Heinsbroek, & Kaushik, ). However, in the current study this was not reflected in growth differences, which also might be due to differences in husbandry conditions between experiments.…”

Optimizing diets to decrease environmental impact of Nile tilapia (Oreochromis niloticus) production

“…In the lower protein diets, more cornmeal and soybean oil were added to balance the dietary energy level. Energetic efficiencies of digestible fat and carbohydrate were shown to be much higher than that of protein for Nile tilapia (Schrama, Haidar, Geurden, Heinsbroek, & Kaushik, ). This suggests that differences in energy utilization of macronutrients should be considered while balancing the diets for dietary energy.…”

Glucose Injection Into Yolk Positively Modulates Intermediary Metabolism and Growth Performance in Juvenile Nile Tilapia (Oreochromis niloticus)

“…Finally, the higher expression of the glycolytic pathway suggests that the early glucose stimulus led to an increase in the use of glucose as an energy source in Nile tilapia (even though tilapia are well known to be a better user of dietary carbohydrates compared to carnivorous fish) (Schrama et al, 2012(Schrama et al, , 2018Polakof et al, 2012;Boonanuntanasarn et al, 2018a,b). Programming of glucose metabolism seems to be associated with a better growth performance between 12 and 16 wpi, suggesting that the early glucose injection could be associated with a better use of carbohydrates, leading to a higher dietary protein-sparing effect.…”