Effect of dried bioflocs as a dietary supplementations on water quality, growth performance and body composition of red hybrid tilapia fingerlings

Abstract

Since the 1990s, biofloc technology (BFT) has become of great importance in aquaculture due to its economic and environmental advantagesto achieve sustainability. One benefit of this technology is that bioflocs can be used as an alternative dietary protein source for aquaculture animals. This would reduce the pressure on traditional protein sources used in fish feed formulation and reduce feeding expenses, which typically account for up to 50% of a farm’s total operating costs. In this thesis, the possibility of using dried bioflocs as a dietary supplement for water quality, growth performance and body composition of red hybrid tilapia fingerlings (4.12±0.07) was investigated in two consecutive experiments. In the first experiment, the effects of two bioflocs sources (tilapia waste and shrimp waste) and two drying methods (freeze drying and oven-drying) on the proximate chemical composition of the bioflocs were investigated and compared. The results of the first experiment indicated that bioflocs derived from tilapia waste could be regarded a more suitable source of dried bioflocs (in terms of protein, energy, and amino acids contents) than bioflocs derived from shrimp waste. Consequently, dried bioflocs derived from tilapia waste and produced by freeze-drying and oven-drying were tested as a dietary supplement in tilapia diets at two different ratios (4% and 16%) for water quality, growth and body composition of red hybrid tilapia during a 57-day feeding trial (the second experiment). Five experimental treatments were prepared: T1 (control; 100% commercial feed), T2 (4% freeze-dried bioflocs), T3 (16% freeze-dried bioflocs), T4 (4% oven-dried bioflocs), and T5 (16% oven-dried bioflocs) to investigate the water quality, growth performance, and body composition of red hybrid tilapia. Statistical analysis showed significant differences within the means for the five treatments (p < 0.05). For water quality parameters, T1, T2 and T4 treatments showed lower electrical conductivity (EC), total dissolved solids (TDS), total suspended solids (TSS), total ammonia nitrogen (TAN), nitrate-nitrogen (NO3-N), phosphate (PO4 - ), biochemical oxygen demand (BOD), and chemical oxygen demand (COD) compared to T3 and T5 treatments. Regarding growth indicators, T1, T2 and T4 treatments had higher final weight, weight gain, specific growth rate (SGR), feed intake (FI) and survival, while feed conversion rate (FCR) and protein efficiency rate (PER) were lower compared to T3 and T5 treatments. The ratio of bioflocs had a greater effect on fish growth and water quality than the drying method. The inclusion of 4% dried bioflocs (produced by either oven-drying or freeze-drying) resulted in better growth performance and water quality compared to the inclusion of 16%. This was also confirmed by the proximate composition results of the whole tilapia body. Tilapia fed 4% dried bioflocs had better body composition than tilapia fed 16%. Protein and energy contents increased with decreasing supplement level of bioflocs. Overall, the supplementation of 4% freeze-dried or oven-dried bioflocs can be successfully included into tilapia diets without affecting the growth or body composition of red hybrid tilapia and may result in good water quality in culture tanks.