Nutritional value of macronutrients for Nile tilapia: Environment matters!

Summary

This thesis explored how two key factors in aquaculture—water temperature and rearing system—influence the nutritional value of feed for Nile tilapia. The two systems tested were a recirculating aquaculture system (RAS) and a pond system. Tilapia were reared for 6–7 weeks, starting at a weight of 39–45 g. Experiments in RAS showed that temperature affected macronutrient digestibility and this depended on the ingredient. The efficiency with which fish used the digested macronutrients for growth was unaffected by temperature. In RAS, digested starch contributed much more to fish growth than digested non-starch polysaccharides (NSP). In the pond system, the estimated energy utilization of protein, fat, starch, and NSP was higher than in RAS, likely due to the presence of natural food. Interestingly, starch utilization exceeded that of protein and fat, suggesting that low-cost, carbohydrate-rich feed ingredients may be more effective in pond systems than in RAS.