Bioavailability of crude protein and lipid from biofloc meals produced in an activated sludge system for white shrimp, Litopenaeus vannamei

Abstract

-The present study compared the bioavailability of crude protein and lipid from biofloc meals generated with an activated sludge system using two water sources: wastewater from shrimp experimental culture (BFL-W) and, artificially, using clean seawater (BFL-C). The sludge system operated by chemical and organic fertilization three times per week. Sampling of bioflocs occurred every two days during 81 days. To evaluate digestibility, each type of biofloc meal was incorporated into a reference diet (REF) at 300 g/kg. Another diet acted as a negative control (NEG) by using fish waste meal. The apparent digestibility of bioflocs was estimated by the indirect method using chromic oxide (Cr 2 O 3 ) as the inert marker at 10 g/kg of the diet. Juvenile L. vannamei of 5.09±0.79 g (n = 440) were stocked at 10 shrimp/tank in 44 tanks of 61 L each that operated under a water recirculating regime. Biofloc meals contained a high ash content (591.0-649.2 g/kg) combined with a low crude protein content (95.9-137.3 g/kg). After 26 days, shrimp achieved a final survival of 93.2±0.8% and a biomass gain of 37.1±1.8 g/tank. Final shrimp body weight ranged from 9.01±0.15 to 9.45±0.13 g. The apparent digestibility coefficient (ADC) of crude protein in the biofloc produced from BFL-W, BFL-C and fish waste meal (NEG) reached 26.0, 25.7, and 64.1%, respectively. Similarly, the lipid ADC was 78.9, 67.9, and 85.8%, respectively. This study indicated that biofloc meals had a low protein availability for L. vannamei. However, although low levels of lipid were present, it proved to be available for the species. The dietary inclusion of biofloc meal appears to have a growth-promoting effect on shrimp, which may be associated with trace minerals, or other nutrients not identified in this study.

Biofloc production in activated sludge system treating shrimp farming effluent

“…Although the levels of ash and crude protein in the bioflocs produced in the activated sludge system were different from those reported in other studies and incompatible with the requirements of L. vannamei, Sabry-Neto, Santaella and Nunes (2015) observed that shrimp gained body mass when provided with feeds containing 30% biofloc, which was produced in an activated sludge system. The production of crude protein in the system probably increases when the C:N ratio decreases.…”

“…Sabry-Neto, Santaella and Nunes (2015) analyzed the nutritional content of biofloc formed in this system and reported that the percentage of ash (64.9%) was higher than that obtained in other studies (24.7 and 11.8% by Kuhn et al in 2009, 27.39% by Ferreira et al in 2015, and 53.95% by Fugimura et al in 2014. The high ash content found in the biofloc probably originated from salts, since the water used to feed the reactor had high salinity (31.44±4.2).…”

Replacement of fishmeal for soy protein concentrate in diets for juvenile Litopenaeus vannamei in biofloc-based rearing system

“…However each nutrient may have a different fluctuation and these differences did not affect the survival or apparent feed efficiency of the shrimp or their composition. This can suggest that diets and biofloc contain sufficient nutrients for shrimp performance, probably because of a growth-promoting effect, which may be associated with trace minerals or other unknown nutrients (Sabry Neto et al, 2015).…”

The Application of Single-Cell Ingredients in Aquaculture Feeds—A Review

“…Less reported has been the digestibility of biofloc products [109][110][111] (Table 4). Each of the biofloc products examined was produced from a different medium and system and the protein content was relatively low in each of the products (11-22%).…”