Dario Rocha Falcon

Non-specific immune parameters and physiological response of Nile tilapia fed β-glucan and vitamin C for different periods and submitted to stress and bacterial challenge.

This study attempts to describe the effects of different administration periods of dietary β-glucan and Vit C on the non-specific immune response, physiological parameters and disease resistance of Nile tilapia against Aeromonas hydrophila infection. Therefore, a feeding trial (288 fish) was conducted to determine the best administration period (7, 15, 30 and 45 days) for a Nile tilapia diet supplemented with 0.1% β-glucan and 600 mg Vit C/kg diet. After the administration period, three different groups of 96 fish were exposed to one of the following three stresses: cold-induced stress, transport-induced stress, and A. hydrophila challenge. Hematological, biochemical and immunological responses were analyzed before and/or after stress. Cold-induced stress increased cortisol levels and reduced the leukocyte count in fish fed the test diet for seven days compared with the other periods. After transport-induced stress, fish fed the test diet for seven days required more hours to return to the baseline levels of cortisol and neutrophils. Moreover, independently of the administration period, fish needed 24 h for leukocyte and glucose levels to return to the initial values. The lowest survival after bacterial infection was observed in fish test diet for seven days. Based on fish hematological and biochemical responses, diet supplemented with 0.1% of β-glucan and 600 mg of Vit C/kg fed for at least 15 days is recommended for Nile tilapia especially when fish are likely to encounter transport-induced stress, and this stress was more severe than cold-induced stress or bacterial challenge.

Lipídeo e vitamina C em dietas preparatórias de inverno para tilápias-do-nilo

In order to prepare tilapia for winter, it were evaluated the effect of two levels of lipid (8.0 and 12.0%) and three levels of vitamin C (300.0; 600.0 and 1,200.0 mg of vitamin C/kg diet), with four replicates each treatment, plus two treatments, absent of test nutrients supplementation and supplemented with 6.0% of lipid and 125.0 mg of vitamin C/kg diet on growth performance and physiologic parameters during 112 days. It was utilized 192 fingerlings, with average weight of 5.57 ± 0.50g. Based on the results it was concluded that the additional energy coming from lipid is accumulated in abdominal cavity; fat deposition as a energy reserve for winter time was obtained in all lipid supplementation, however 8.0% supplementation seems to be more appropriate; the concentration of 600.0 mg of vitamin C/kg diet appears to be more economically appropriate and that vitamin C absence impairs erythropoiesis and collagen syntheses.

Digestibilidade de alimentos protéicos e energéticos para fêmeas de beta

Apparent digestibility coefficients of dry matter, crude protein, gross energy and ether extract from protein feeds: soybean meal and fish meal and from energy feeds: corn and wheat middlings were evaluated for Siamese fighting fish (Betta splendens). Adult female fish were stocked in cages and held in two fiberglass aquaria (30 fish/aquarium) for feeding and two aquaria for collect fecal samples, both with conic shape with 30L. The results of apparent digestibility coefficients for DM, CP, GE and EE were respectively 69.43, 72.52, 67.91 and 55.50% for soybean meal; 60.67, 51.15, 75.55 and 58.26% for fish meal; 63.88, 87.16, 77.61 and 50.40% for corn and 61.06, 93.37, 58.17 and 65.51% for wheat middlings. The determined digestibility values are essential to economically viable practical diet formulation for Siamese fish fighting.

Digestibilidade aparente de rações contendo complexo enzimático para tilápia-do-nilo

Apparent digestibility (ADC) of five isoproteic and isoenergetic diets containing 0, 0.1, 0.2, 0.3, and 0.4g/kg of enzymatic complex Bioenzimaplus (lipase, protease, and carbohydrase) for Nile tilapia was evaluated. A hundred fish were randomly assigned in five feeding aquaria, and five collecting feces ones. Treatments were composed by five enzymatic complex levels arranged in a completely randomized design in five repetitions. Significant differences (P<0.05) were observed with the inclusion of enzymatic complex in the diets for ADC of crude protein and fat (linear effect). ADC of crude protein and fat varied from 81.60% to 84.94% and 74.19% to 85.69%, respectively. The highest enzyme supplementation level showed better digestibility values for carbohydrate and gross energy (57.85% and 63.78%, respectively). No difference was observed for ADC of dry matter showing values between 49.47% and 58.55%. The use of enzymes in Nile tilapia diets improved the digestibilities of protein, fat, carbohydrate, and gross energy digestibility.