Abstract
This study aimed to assess the effect of dietary macronutrient composition on the relationship between RE and DE intake (i.e., the maintenance energy requirements and the slope [kgDE]); to quantify the energy utilisation efficiencies of digested protein, fat and carbohydrates for whole body growth as well as fillet growth in striped catfish (Pangasius hypoththalmus). To achieve these aims, a 63-day experiment was conducted on striped catfish (29.1 g). A total of 4 diets were studied at 2 feeding levels, low vs. high (12 vs. 22 g.kg−0.8.d−1, respectively), which resulted in a 4 × 2 factorial design. The four diets had contrasting inclusion levels of protein, fat and carbohydrates. Striped catfish digested part of the non-starch polysaccharides (33.6–71.0%) while starch is almost completely digested (> 94%). By conducting the regression between RE and DE intake over diets, the energy utilisation efficiency for striped catfish was estimated at 71% through the equation: RE = − 42 (se 9.2) + 0.71 (se 0.049) DE intake, (R2 = 0.95). Dietary macronutrient composition did not affect the relationship between RE and DE intake. Multiple regression between RE as a function of digested protein, fat and carbohydrates intake (in g.kg−0.8.d−1) was also conducted to estimate the energy utilisation efficiency of digested protein, fat and carbohydrates. The estimated energy efficiencies of digested protein, fat and carbohydrates for energy retention at the whole fish level were 64%, 80% and 58%, respectively. The energetic values of dCP, dFat and dCarb for whole body growth differ from the energetic values for fillet production. For fillet growth, digested protein had a higher potential compared to digested fat and carbohydrates, however this needs to be used in a balanced ratio with digested fat and carbohydrates.
Highlights
Protein, fat and carbohydrates can provide the essential energy needs of fish for maintenance and growth
To fulfil the above described knowledge gaps for striped catfish, this study aims to: 1. assess the effect of dietary macronutrient composition on the relationship between retained energy (RE) and digestible energy intake (DE) intake; 2. quantify the energy utilisation efficiencies of digested protein, fat and carbohydrates for whole body growth on striped catfish to be able to use a net energy (NE) evaluation system for striped catfish; 3. quantify the energy potential of digested protein, fat and carbohydrates to contribute to fillet growth in contrast to the growth of the other defined body compartments
Starch supplementation increased the apparent digestibility coef ficient (ADC) of NSP from 51% to 62%, averaged over the low starch diets and the high starch diets (P < 0.01), while fat supplementation decreased the ADC of NSP from 61% to 50% averaged over the fish fed the low fat diets and the fish fed the high fat diets (P < 0.01) (Fig. 1)
Summary
Fat and carbohydrates can provide the essential energy needs of fish for maintenance and growth. Fat and carbohydrates are preferably used for energy supply, either directly for ATP production or indirectly in the form of fat storage for future energy needs, in order to spare protein. The success of culturing striped catfish depends on the efficient conversion of protein, fat and carbohydrates into growth. To achieve an efficient feed conversion, formulating balanced diets requires information on the amount of nutrients needed for maintenance and for growth. Especially newly cultured fish species, such nutritional information is often lacking. Striped catfish is one of the major fish species cultured worldwide (FAO, 2018). Striped catfish is already cultured at a large scale for some time, information regarding their nutritional requirements is still limited
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
