Fermentacion biologica de lodos de la industria atunera como fuente potencial de proteina para la nutricion de tilapia (Oreochromis niloticus) (Spanish text).

摘要

Three experiments were undertaken to develop methodologies to apply lactic acid fermentation (LAF) to the sludge from tuna processing plants (STPP) as an alternative to provide protein for aquaculture. The first experiment consisted of determining the effect of adjusting humidity (heat or decanting), adding lactic acid producing bacteria (LAPB), and sucrose on the fermentation and chemical composition of STTP, during different periods of fermentation. The results indicated that the application of heat did not improve the fermentation characteristics of STTP. The final product had a good nutritional composition and low pH values that made it appear to be a viable protein supplement. The use of 5% synthetic sucrose and LAPB permitted the fermentation of STPP.; The second study consisted in obtaining a safe and stable product from a microbiological stand point. The best combination of treatments from the first study, T1: 5% sucrose and T2 LAPB and 5% sucrose were used to determine changes in microbial populations, fermentation characteristics, chemical composition and pH of STPP during different fermentations periods (0, 2, 4, 7, 9, 14, 28 and 56 days). Significantly lower (P 0.05) pH values and greater (P 0.05) production of lactic acid took place in T1, without differences on volatile fatty acids. Greater growth of LAPB with the elimination (P 0.05) of total coliforms after day 4 was found with T2. However, the number of molds and yeast remained relatively constant starting on day 7. In addition, T2 obtained greater levels of dry matter and crude protein. With T2, it was possible to obtain a stable product from a microbiological stand point after 9 days.; The third study consisted in the evaluation of the nutritional content of fermented SM as a protein source for Oreochromis niloticus. The dietary protein provided by fish meal (FM) was progressively replaced by dry LAFS at 0%, 20%, 40%, 60%, 80% and 100% levels in diets for tilapia (11.46 ± 0.19g), a second control diet was included (commercial diet), and isocaloric (4.5 Kcal.g−1) and isonitrogenous (30% crude protein) to evaluate the effect on growth, feeding efficiency, and survival. All groups showed good growth and feed efficiency during the experimental period, with specific rate growth (SRG) from 2.16 to 2.33 and food conversion from 1.26 to 1.39 (FC). As the levels of fermented STPP increased in the diet the carcass ash content decreased (P 0.05), without differences (P > 0.05) in protein, lipid or moisture. No mortality occurred for any treatment during the feeding trial.; In conclusion, it is possible to apply LAF to STPP with the combination of 5% of synthetic sucrose and LAPB during a 9 days period. The use of decanting as a methodology for adjusting humidity resulted in an effective method for this objective. The LAF of STTP appears as a potential alternative to produce by-products for replacing FM in diets for tilapia, without causing negative effects on feed utilization, growth, and body composition.