Marine microalgae commercial production improves sustainability of global fisheries and aquaculture

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Used of microbial phytase to replace inorganic phosphorus in sex-reversed red tilapia: 1 dose response

Sex-reversed red tilapia of average initial body weight 5.5 g were fed seven practical diets containing 0, 500, 1,000, 2,000 and 4,000 units of microbial phytase/kg and two diets containing 0.2 and 0.3% feed grade dicalcium phosphate (DCP) (but no microbial phytase), respectively. The experiment was carried out in 235- l glass aquaria filled with 180 l water and attached with a closed-recirculating water system with 0.8 l/min flow rate. The experimental period was 10 weeks. All experimental diets were formulated with plant-based protein of 30% and 6% fat. Results indicated an improvement in apparent digestibility coefficient of phosphorus (ADCP) in fish given phytase supplemented feed. There was no difference in ADCP when 1,000 unit phytase/kg diet or higher phytase levels (2,000 and 4,000 unit phytase/kg diet) or 0.2 and 0.3% DCP were supplemented. A significant increase was noted for hemoglobin in tilapia that received 1,000 unit phytase/kg diet or higher levels compared to the control. Serum phosphorus ma kedly increased when the fish were given feeds with 1,000 unit phytase/kg diet and over, while the supplementation of 500 unit phytase/kg diet and over increased serum zinc level. Higher levels of phosphorus were retained in bone whereas lower levels of phosphorus presented in the feces of tilapia fed feeds supplemented with phytase. Growth performance was markedly influenced when the fish were given feed with 4,000 unit phytase/kg diet

Wutiporn Phromkunthong

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The supplementation of phytase RONOZYME P on the growth and the utilisation of phosphorus by sex-reversed red tilapia (Oreochromis niloticus Linn.)

The effect of phytase supplementation to a low fish meal based diet on growth performance and phosphorus utilisation was investigated in sex-reversed red tilapia. Diets were prepared without phytase or inorganic phosphorus supplementation, with phytase, with supplemented inorganic phosphorus and with both phytase and supplemental inorganic phosphorus. Available phosphorus was set below requirement and the total phosphorus set to meet requirement for tilapia. After 8 weeks, there were significant differences in weight gain and protein utilisation between diets. There was an effect of phytase addition and inorganic phosphorus supplementation on bone phosphorus and whole-body phosphorus (p<0.05). A significant effect was also observed on phosphorus digestibility, phosphorus retention efficiency and phosphorus load of the water. Phosphorus digestibility and retention efficiency were significantly (p<0.05) higher, and phosphorus load of the water was significantly (p<0.05) lower in fish fed the phytase supplemented diet compared with diets containing supplemental inorganic phosphorus and the basal diet. In conclusion, phytase increased phosphorus availability, therefore reducing the need to add inorganic phosphorus and reducing phosphorus waste from low fish meal based diets for tilapia

Dietary exposure to melamine and cyanuric acid induced growth reduction, oxidative stress and pathological changes of hepatopancreas in Pacific white shrimp

Abstract This study examined the effects of dietary melamine (MEL) and cyanuric acid (CYA) singly and in combination on growth, nutrient utilization, immunological responses, oxidative stress, and histological changes in Pacific white shrimp. Seven experimental isonitrogenous (35%) and isolipidic (8%) diets were formulated, namely diet 1 (a control diet without MEL and CYA); diets 2–5 (with MEL and CYA at 2.5 + 2.5, 5 + 5, 7.5 + 7.5 and 10 + 10 g kg−1 diet); diet 6 (with only MEL at 10 g kg−1 diet) and diet 7 (with CYA alone at 10 g kg−1 diet). The shrimp with initial body weight 2.37 ± 0.02 g were fed with these diets for 10 weeks. The results indicate that all the diets with MEL and CYA singly or in combination had adverse effects on growth and nutrient utilization relative to the control diet (p < 0.05). Total protease and trypsin activities were significantly lowered by all diets containing MEL (p < 0.05). Haemolymph parameters, including total hemocyte count, phenoloxidase (PO) activity, respiratory burst, and lysozyme activity, were significantly decreased (p < 0.05) in shrimp receiving MEL alone (10 g kg−1 diet) and at high combination dosages (10 + 10 g kg−1 diet). Moreover, MEL and CYA induced oxidative stress, damaged hepatopancreas, decreased antioxidant responses, increased lipid peroxidation, and caused abnormality of hepatocytes