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931.
Some Limiting Factors in Superintensive Production of Juvenile Pacific White Shrimp,Litopenaeus vannamei,in No‐water‐exchange,Biofloc‐dominated Systems
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David I. Prangnell Leandro F. Castro Abdulmehdi S. Ali Craig L. Browdy Paul V. Zimba Susan E. Laramore Tzachi M. Samocha 《Journal of the World Aquaculture Society》2016,47(3):396-413
Superintensive shrimp culture in zero‐exchange, biofloc‐dominated production systems is more biosecure and sustainable than traditional shrimp farming practices. However, successful application of this technology depends upon optimizing dietary formulations, controlling Vibrio outbreaks, and managing accumulative changes in water quality and composition. A 49‐d study investigated the effect of two commercial feeds of differing protein content and an indoor limited‐exchange, biofloc‐dominated culture environment on Litopenaeus vannamei performance and tissue composition, water quality and ionic composition, and Vibrio dynamics. Juveniles (5.3 g) were stocked at 457/m3 into four 40 m3 shallow raceways containing biofloc‐dominated water and fed one of two commercial feeds with differing protein content, 35 or 40%. Shrimp performance, Vibrio populations, and changes in shrimp and culture water composition were monitored. There were no significant differences (P > 0.05) in shrimp performance (survival, weight, growth, specific growth rate, total biomass, yield, feed conversion ratio, and protein efficiency ratio) or proximate composition between feed types. The 40% protein feed resulted in higher culture water nitrate and phosphate concentrations, alkalinity consumption and bicarbonate use, and higher phytoplankton density. The presence of Vibrio, specifically Vibrio parahaemolyticus, reduced shrimp survival. This survival decrease corresponded with increased culture water Vibrio concentrations. Culture water K+ and Mg2+ increased significantly (P < 0.05), and Sr2+, Br?, and Cl? decreased significantly (P < 0.05) over time. While Cu2+ and Zn2+ did increase in shrimp tissue, no heavy metals accumulated to problematic levels in culture water or shrimp tissue. These results demonstrate the importance of monitoring Vibrio populations and ionic composition in limited‐exchange shrimp culture systems. 相似文献
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934.
I. Placha M. Pogany Simonova K. Cobanova A. Laukova S. Faix 《Research in veterinary science》2010,89(2):257-261
We investigated the effect of Enterococcus faecium on phagocytic activity, antioxidative status in vivo and the effect of E. faecium and 0.4% concentration of Thymus vulgaris essential oil (EO) on the duodenal tissue integrity in vitro in laying hens. The birds were fed the same standard diets and were divided into four groups. E. faecium was added to the drinking water for the second and fourth groups. EO was added to special chambers for measuring trans-epithelial electrical resistance (TEER) for the third and fourth groups only. TEER was lower in groups where EO was added, but in the group with E. faecium TEER was not changed significantly. Our results show that EO at 0.4% concentration may negatively affect intestine integrity, and the probiotic strain E. faecium AL41 is able to eliminate this effect and can strengthen non-specific immunity. To confirm our findings further histopathological investigations of intestinal tissue are needed. 相似文献
935.
It has been found that mechanical activation of amorphous carbon obtained from Katerina SV corn waste encourages formation of carbon nanotubes. At the same time, carbon tube output after 7 and 42 hours of mechanical activation is 11 and 42% by weight, respectively. 相似文献
936.
G. Yu. Rabinovich Yu. I. Mitrofanov V. A. Kotelnikov D. V. Tikhomirova 《Russian Agricultural Sciences》2013,39(5-6):468-470
Microbiological testing (bioindication) of fallow lands of ameliorative objects in the humid zone has been carried out. It is shown that soils of plots with an unsatisfactory water and air regime are characterized by increased enzyme activity, high level of the redox ratio, and high content of labile humus and nutrient elements in a mobile form. On plots with a favorable water and air regime, activation of mineralization processes with no means for restoring fertility is also a negative factor. Such evaluation allows determining the necessary rehabilitation measures. 相似文献
937.
The plasticity and stability of hybrids selected from three heavy-eared populations according to the gluten deformation index GDI-1 are shown. The possibility of testing closely related genotypes by criteria based on ecological regression is examined. Hybrid forms valuable in adaptability that can be used in breeding are found. 相似文献
938.
The effect of growth-promoting rhizobacterium Pseudomonas fluorescens 21 on barley yield and grain quality was examined at growing plants in artificially Pb-contaminated gray forest soil. Application of bacterium eliminated Pb toxicity, significantly reduced metal uptake in shoots and increased grain yield without changing its quality. 相似文献
939.
The probabilistic approach methodology that assesses the permissible level of heavy metal (HM) pollution of agricultural land according to sanitation and hygiene principle is developed. Application of the methodology is illustrated by using information from the database, which characterize parameters of zinc transition from the soil to agricultural plants. 相似文献
940.
A method to improve the air regime of soil by reducing its density and increasing its total porosity has been suggested. This method consists in adding organo-mineral compost, which is based on agricultural and industrial wastes, to the topsoil. 相似文献