Fish were fed diets containing dehydrated ginger powder (GgP) to determine its effects on growth, immune response, antioxidant capacity and resistance to Aeromonas hydrophila infection. 540 Nile tilapia were distributed in 36 250 L aquaria and fed six isonitrogenous and isoenergic diets supplemented with six graded levels of GpP: 0, 2.5, 5, 7.5, 10 and 15 g/kg, during 30 days. After that, growth, hemato‐immunological parameters and antioxidant enzymes activities were determined. All parameters, but growth, were re‐evaluated after the bacterial infection challenge. Fish fed diets up to 5 GgP showed higher body weight and specific growth rate compared with 0 GgP. Fish fed 10 GgP showed the highest H2O2 and NO compared with 0 GgP (p < .05). Fish fed 2.5 GgP and 10 GgP maintained catalase and superoxide dismutase activities after infection. The highest survival was observed for fish fed 10 GgP. The best results for specific growth rate and feed conversion ratio were determined at 4.1 and 5.8 g/kg of GgP and for survival rate and immunological response at 10 g/kg of GgP. In sum, 10 g/kg GgP is indicated to improve Nile tilapia growth performance and resistance against Aeromonas hydrophila infection.
This study evaluated the effects of phytase supplementation on growth performance and apparent digestibility of Nile tilapia (Oreochromis niloticus) in a commercial fish farm setting. Nile tilapia (6300 male, 57.48 ± 1.04 g) were randomly stocked into 42 floating cages. The experimental design was completely randomized, comprising six treatments and seven replications. Fish were fed five phosphorus deficient plant-based diets with graded levels of phytase supplementation (0, 500, 1000, 1500, 2000 UF kg−1) and an additional diet containing phosphorus supplementation to meet the requirement of this fish species (positive control). After 97 days of feeding, growth performance data were collected and 900 fish (500 ± 10 g) were relocated to 6 floating cages for the digestibility assessment. Quadratic polynomial regression analysis indicated 1537.5 and 1593.2 UF kg−1 as the optimum dietary levels for daily weight gain and feed conversion rate, respectively. Including 2000 UF kg−1 resulted in the higher dry matter, crude protein, energy, and ash apparent digestibility coefficient values. Therefore, phytase supplementation from 1500 to 2000 UF kg−1 is recommended to enhance growth performance and nutrient bioavailability of Nile tilapia reared according to industry practices.
Zebrafish (Danio rerio) is a southeastern Asian teleost that has been widely used as an experimental model due to some of its characteristics, such as rapid development, high reproductive capacity and transparency larval development (Kaushik et al., 2011). Besides the aforementioned characteristics, studies have shown that the genome sequence of this cyprinid is similar to mammals (Dahm & Geisler, 2006;Jones, 2007). In fact, such similarity supports the use of this animal as a feasible genetic model to genome studies (Orban & Wu, 2008). Zebrafish is used as a model not only to genetics research but also for haematological, cardiological, oncological, toxicological, regenerative medicine, nutrigenomic, environmental ecotoxicology, stem cell, molecular biology, metabolic disorder, tissue regeneration and therapeutics drug assays (
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