الفهرس 
CoverOnly 14 pages are availabe for public view
 |  | from | 107 |  |  |
| | | from | 107 | | |
Abstract
Biofloc technology (BFT) is a simple approach that allows for more efficient use of water and space, also supplying a possible protein resource for cultivated organisms. The strategy of nutrient recycling is the primary concept of this approach. It is derived from the continued addition of various carbon sources to modify carbon/nitrogen ratio (C/N) through culture water which would in turn proliferate heterotrophic bacterium and the synthesis of microbial biomass. Unfortunately, the slow progression of nitrifying bacteria throughout the BFT system is considered a drawback of this technique. Furthermore, certain opportunistic and harmful bacteria species are likely to thrive and spread alongside beneficial biofloc microbial aggregates, compromising fish health and survival.
On the other hand, probiotics in aquaculture have sparked a lot of interest in the last two decades. There is a need to understand the symbiotic’s role in the culture performance of Nile tilapia under the biofloc framework. As a consequence, the focus of this study was to evaluate the cultural performance of Nile tilapia in traditional conventional system and biofloc systems with various C/N ratios and diverse probiotic applications as water additives.
Juvenile O. niloticus were randomly assigned in nine replicated treatments. They were kept at a density of 120 fish m-3, where their average initial weight was 16.72g fish-1. The experiment was conducted for 14 weeks. The experiment was assembled as a control conventional system (CS), CS+B. subtilis, CS+L. acidophilus, biofloc (BFT)-10:1, BFT-10:1+ B. subtilis, BFT-10:1+ L. acidophilus, BFT-20:1, BFT-20:1+B. subtilis, and BFT-20: 1+L. acidophilus. Culture performance parameters of juvenile tilapia were tested.
The results revealed that BFT application and or probiotic addition significantly
improved the water quality more than the CS group. Regardless of probiotic addition, BFT aquaculture systems improved the Nile tilapia fingerlings’ growth compared to the conventional system. Symbiosis of BFT-10:1 with B. subtilis probiotics accomplished the highest growth performance parameters with a pronounced improvement in feed utilization compared to the control CS groups either with or without probiotics addition.
Moreover, the application of BFT systems could efficiently boost total bacterial count (TBC) in culture water and gut microbiota either alone or with probiotic enrichment, where the highest TBC count was presented in BFT-20:1+ B. subtilis and BFT-20:1+ L. acidophilus.
The use of B. subtilis or L. acidophilus probiotics as water supplements in either the classic conventional culture method or the biofloc system increased digestive enzyme efficiency. Also, the histological investigation demonstrated improved gut morphology in BFT and/or probiotic treatments in the way of increasing villus height, width, goblet cell abundance, and crypt depth in the middle part of the intestine, suggesting improved intestinal health and immunity.
The inclusion of B. subtilis or L. acidophilus probiotics as water additives in either the classic conventional system or the biofloc system increased hematological parameters, non-specific immune response in Nile tilapia. When probiotics were added to the biofloc system, the elevation pattern became more evident, especially with a C/N ratio of 10:1, which produced the most significant outcomes. Also, the application of.