Feeding management strategies to optimize the use of suspended feed for Nile tilapia ( Oreochromis niloticus ) cultivated in bioflocs

Abstract

Feeding strategies of tilapia (initial average weight: 32 g) cultivated with Biofloc technology (BFT) (carbon source: sugarcane, C:N ratio: 6:1) for 56 days were studied. A 4 × 3 factorial experimental design was used with four feeding frequencies (one, two, three and four times a day) and three feeding rates (50%, 75% and 100% consumption in relation to apparent satiety), with four replicates. Lower levels of dissolved oxygen, protein retention rate and body protein content were found in fish fed once a day. The reduction in feeding rate resulted in lower average final weight and reduced growth but promoted a decrease in the concentration of total ammonia nitrogen, solids, hepatosomatic index and body lipids. We found better efficiency of protein utilization at 75% feed. The nutritional value of the floc was not affected by the feeding frequency, and the feeding rate reduction from 100% to 75% did not alter the protein content of the floc. Thus, twice‐daily feeding frequency is sufficient for Nile tilapia fingerlings reared in BFT. Although the feeding rate of 100% satiety has led to better performance, it may not be the best option in BFT due to higher feed conversion and reduction of water quality.

Nile tilapia nursery feeding management in a biofloc system

“…Unlike this study Silva et al (2020) observed that the higher feed rate did not change the nitrite concentration in the water, and decreased pH and alkalinity values. This is due to the higher nitrification rate required in rearing with a higher feed rate, which results in higher carbonate consumption and greater release of H+ ions by nitrification.…”

“…However, a low feeding rate can also delay animal growth. On the other hand, a high feeding rate can impair water quality, affecting growth, in addition to causing physiological problems in the liver and blood of fish (Huang et al, 2015;Silva et al, 2020).…”

“…Recent studies evaluating different feeding rates of tilapia in biofloc systems have adopted different strategies. Silva et al (2020) observed the feeding of juvenile tilapia with different feeding rates based on apparent satiety. However, restricted feed management generally results in a lower feed conversion rate than that achieved by ad libitum management, in addition to being more easily performed by fish farmers in practice (Oliveira et al, 2021).…”

Supplementation of the commercial diet of Nile tilapia (Oreochromis niloticus) with DL-methionine and soybean oil under feed restriction

“…The dry biomass of bioflocs contained 24.76 ± 0.42% and 1.39 ± 0.14% of crude protein and ether extract, respectively. Unlike the present study, Silva et al (2020) observed that the feeding rate of the animals influenced the chemical composition of the bioflocs. In this work, halving the feed rate reduced the crude protein content of bioflocs from 25% to 21%.…”

“…The great variability in their chemical composition and the deficiencies in some amino acids and essential fatty acids make the isolated use of bioflocs as food for aquaculture unfeasible. Thus, it would be important to evaluate the use of different combinations between artificial diets and bioflocs, in fish and shrimp tanks, to obtain the best possible productive results, in each case (Silva et al, 2020).…”