Different sources of phosphorus supplementation and its excretion by Nile tilapia juveniles (Oreochromis niloticus)
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Fish farming causes environmental impacts due to the wastewater produced by fish excreta and unconsumed feed. The differences in phosphorus excretion by Nile tilapia (Oreochromis niloticus) juveniles when fed diets composed with different phosphorus sources were evaluated. Six isonitrogenous and isocaloric diets were formulated containing 28% crude protein and 3,000 kcal DE kg-1 with levels of 0.8% total phosphorus, and the following ingredients were used as phosphorus source: dicalcium phosphate, meat and bone meal, poultry by-product meal, anchovy meal, tilapia filleting industrial waste, and calcined bone meal . Fish (120 tilapia juveniles) with a mean weight of 94.23 ± 0.28 g and total length of 16.8 ± 0.32 cm were distributed in six 60 L tanks for analysis of the diets digestibility. Diet with dicalcium phosphate presented the lower phosphorus excretion, with retention of 10.05 and excretion of 1.95 kg of phosphorus per ton of tilapia. Diets formulated with lower quality ingredients, such as calcined bone meal and meat and bone meal provided a phosphorus retention of 7.45 and 7.64 and an excretion of 4.55 and 4.36 kg per ton of fish, respectively.