No abstract

The production of aquatic organisms for human consumption has been decreasing while its demand has increased. The decline of fish products from fisheries has been in part compensated by the aquaculture industry. The need for enhanced disease resistance, feed efficiency, growth performance and lower production costs of cultured organisms is substantial for various sectors of this industry. Different products have been used at some extent to prevent disease and as growth promoters; however, their inadequate application can create adverse disorders, environmental imbalances, and increase predisposition to disease. In the search of new disease control and prevention options, several studies have been carried out to test some functional additives (probiotics). Probiotics have been shown to improve energy expenditure derived from sources such as carbohydrates and increase the incorporation of protein for growth; and to increase the immunity and disease resistance of the host. The use of probiotics in aquaculture has high potential application at a commercial level; however, it has been poorly characterized and studied. This study aims to review the use and action of probiotics in the culture of aquatic organisms (bivalve, fish, shrimp); and the potential for further application of this in aquaculture production.

The intestinal microflora of Nile tilapia (Oreochromis niloticus) fish was studied to isolate and identify lactic acid bacteria as new probiotic. A total of five lactic acid bacteria were isolated from intestine to evaluate with antibacterial properties. These strains were identified by conventional and molecular techniques as: Enterococcus faecium, Leuconostocmesenteroides, Lactobacillus fermentum, Lactobacillus plantarum, Enterococcus durans. Leuc.mesenteroides present more ability to inhibit growth of fish pathogens bacteria and selected as possible probiotic bacteria to use in aquaculture.

Two feeding experiments were carried out to evaluate the effect of partial substitution of fish meal (FM) with raw or heat‐treated cowpea Vigna unguiculata L. Walp var. IT86‐D719 seeds on growth performance, digestibility and pancreas tissue in Nile tilapia (Oreochromis niloticus L.) fry. Experiment 1 involved six isonitrogenous and isocaloric diets: four containing different concentrations of raw, whole cowpea meal (protein basis), a positive control with FM as sole protein source and a negative with cowpea meal as sole protein source. Substitution at up to 200 g kg−1 had no significant effect on production parameters, although growth was negatively affected in the negative control because of seed antinutritional factor content. Experiment 2 evaluated the effect of heat treatment (oven drying at 48 °C; hot air drying at 70 °C; or autoclaving at 119 °C) and/or seed dehulling using diets containing 200 g kg−1 cowpea meal presoaked in water. Only autoclaving eliminated trypsin inhibitor and lectin contents, independent of dehulling. Histological analysis indicated no histological changes in pancreas tissue. Raw or treated cowpea meal can replace FM in tilapia fingerling diets at up to 200 g kg−1 protein content without significantly affecting productive parameters or pancreas tissue.