Effects of different stocking densities and supplementation with Saccharomyces cerevisiae in juvenile Nile tilapia cultivated in a recirculating water system (RAS)

The objective of this study was to evaluate the productive performance, organosomatic indices and liver-intestinal histomorphometric parameters of Nile tilapia (Oreochromis niloticus) juveniles, fed diets containing probiotics (yeast - Saccharomyces cerevisiae) and reared at different densities of storage. In this experiment, 450 juveniles of tilapia (2.9 ± 0.23 g) were distributed in 18 experimental units arranged in RAS and arranged in a randomized block design in a 2x3 factorial scheme. These animals were fed two diets, the first without yeast and the second containing 0.1% yeast inclusion and distributed in three stocking densities of 15, 25 and 35 fish / m3 (500, 833 and 1166 fish / m3). There was an improvement in the oxygenation of the medium with the use of yeast, as well as in the lowest stocking densities evaluated (15 and 25 fish / m³). However, lower specific growth rates and higher viscerosomatic index were observed in animals supplemented with 0.1% yeast. For the average area of hepatocytes, there was an interaction between the evaluated factors (use of probiotic x storage density), where the best values were found in the lowest storage densities (15 and 25 fish / m³), regardless of use or not of the probiotic. It is recommended to use a stocking density of 15 to 25 fish / m³ and a supplementation of 0.1% with yeast as a probiotic, in order to improve liver health and oxygenation of the water used to grow Nile tilapia juveniles cultivated in RAS.

Effect of different maturation diets on reproductive performance of the broodstock of purple mangrove crab, Scylla tranquebarica

The present study was aimed at evaluating the reproductive performance of the broodstock of purple mangrove crab (Scylla tranquebarica) fed natural food and formulated diets supplemented with astaxanthin and/or DHA. Formulated diets were supplemented with 500 mg kg-1 of astaxanthin (FA), 10 g kg-1 of DHA (FD) and both astaxanthin and DHA (FA+D). Diet without astaxanthin and DHA (FCon) and natural food (NF) consisted of forage fish (Valamugil sp.), shrimp (Penaeid sp.) and mangrove clam (Polymesoda sp.) to serve as control. Female broodstock of initial body weight 129.07±17.03 g were stocked in HDPE tank and cultured under recirculating water system. Broodstock maturation was monitored until spawning. Reproductive performance of female and condition of the larvae were also evaluated. After 50 weeks, broodstock fed FA+D diet showed better maturation percentage, spawning rate, gonadosomatic index, oocytes diameter, molting, molt death syndrome and survival rate than FCon group (P0.05) to the FA+D group but diet FD resulted in better performance than FA. Broodstock fed FA+D diet had the highest hatching rate, number of larvae produced and significantly higher zoea II survival compared to FCon and NF groups (P

Ozonated water in the post-harvest treatment of coffee fruits

ABSTRACT Ozone is used in many countries for the treatment of effluents, becoming a viable alternative in sanitation of coffee wastewater. However, the strong ozone oxidation, responsible for its germicidal effect, can also compromise grain and beverage quality. The objective of this study was to evaluate the quality of Arabica coffee in different periods of treatment with ozonated water and its effect after drying. Coffee fruits were subjected to ozonation at regular intervals of 0, 5, 10, 20, and 30 min, with continuous stirring promoted by a recirculating water system at constant rate of 1 ppm of solubilized ozone. The design was completely randomized with five treatments and four replicates. After obtaining the data, the analysis of variance was performed and means were compared by Tukey test (p ≤ 0.05). The results showed a partial reduction of fungi after washing with ozonated water, but the same effect was not observed after drying. For coffee quality analysis, the longest times of exposure to the solubilized gas in the water produced some negative results in electrical conductivity and total and reducing sugars. However, the sensory quality of the beverage was maintained.

Substrates for biofilter in recirculating system in Nile tilapia larviculture production

SUMMARY Recirculating water system (RAS), provide to reduce water usage and to improve the quality by nutrient recycling, so biofilters are used to reduce ammonia concentrations by oxidation to nitrate, by nitrifying-bacteria. Biological filters have been utilized to maintain acceptable water parameters to larvae and juveniles, by decreasing ammonia concentrations. The objective of this experiment was to evaluate different substrates for aquarium biofilter on performance of Nile tilapia (Oreochromis niloticus) larvae, and water quality. One-thousand-two-hundred Nile tilapia larvae (initial length = 11.6 ± 0.82 mm; body weight (BW) =189.0 ± 0.44mg) were randomly allotted into one of twenty 6-L aquariums (60 larvae aquarium-1) with five different biofilter (4 aquariums each biofilter): (1) control, no substrate; (2) seashell-and granitic crushed stone-substrate; (3) granitic crushed stone substrate; (4) quartz gravel substrate; and (5) porcelain-substrate. The conductivity, turbidity, pH, nitrate, nitrite and ammonia values indicate that seashell and granitic crushed-stone, and porcelain-substrates had greater process of biofiltration effectiveness. Water oxygen did not differ among treatments, with all levels within the benchmark for the tilapia larvae. Fishes reared in aquarium with quartz gravel-and porcelain substrate fishes had greater BW, total and standard length compared with its from other substrates. Porcelain-substrate biofilter is indicated for tilapia larviculture due to improved weight and length and water quality.