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A 30-day experiment was conducted to evaluate inorganic nitrogen control, biofloc composition and shrimp performance in zero-exchange culture tanks for juvenile L. vannamei offered a 35% (P35) or 25% (P25) crude protein feed, each feed supplemented with additional carbohydrate to increase the C/N ratio to 20:1 ( CN20) or 15:1 ( CN15). Sucrose was used as a carbohydrate to manipulate the two C/N ratios based on the carbon and nitrogen content of both the feeds and sucrose. The four treatments were referred to as: P35 + CN20, P35 + CN15, P25 + CN20 and P25 + CN15. Each treatment consisted of four replicate tanks (125 L), each stocked with 28 shrimp (equivalent to 224 shrimp m−3). Bioflocs formed and developed based on initial inoculation in all four treatments; and monitored water quality parameters were maintained within acceptable ranges for shrimp culture throughout the experiment. No significant effects ( P > 0.05) of dietary protein level, C/N ratio or their interaction were observed on biofloc development ( BFV, TSS and BFVI) and inorganic nitrogen ( TAN, NO2−-N and NO3−-N) concentrations. At the end of the experiment, proximate analysis of the bioflocs collected from the four treatments showed crude protein levels of 21.3% ~ 32.1%, crude lipid levels of 1.6% ~ 2.8% and ash levels of 43.4% ~ 61.4%. Extracellular protease and amylase activities of the bioflocs were 9.9 ~ 14.4 U g−1 TSS and 293.5 ~ 403.8 U g−1 TSS respectively. Biofloc composition and enzyme activity were both affected by dietary protein level ( P < 0.01) and C/N ratio ( P < 0.05). Survival, per cent weight gain and protein efficiency ratio of shrimp were not affected ( P > 0.05) by dietary protein level, C/N ratio or their interaction; however, the feed conversion ratios were significantly lower ( P < 0.05) in treatments with high dietary protein (P35) compared with those in treatments with low dietary protein (P25). The results from this study demonstrate that dietary protein level and C/N ratio manipulation can have important implications for water quality, biofloc composition and shrimp performance in intensive, zero-exchange biofloc-based culture systems. [ABSTRACT FROM AUTHOR]

A 30-day experiment was performed to investigate the effects of bioflocs on water quality, and survival, growth and digestive enzyme activities of the white shrimp Litopenaeus vannamei. Altogether 28 shrimp (7.4 ± 0.1 g) were stocked in each 150 L tank. Two bioflocs treatments and one control were managed: 'bioflocs 1' and 'bioflocs 2' based on two different densities of the bioflocs, and clean water control without the bioflocs. Brown sugar was added to the bioflocs 1 and bioflocs 2 treatment tanks accounting for 28% and 80% of the shrimp feed respectively (corresponding to proximate C/N ratios of 10 and 14 in daily additions of organic matter respectively), so as to promote bioflocs production and approximately 14 mL L−1 in treatment bioflocs 1 and 20 mL L−1 in treatment bioflocs 2 were maintained from day 15. Monitoring of selected water quality parameters throughout the whole experiment period showed that all parameters remained within recommended levels for shrimp culture in the bioflocs treatments at zero-water exchange, especially low total ammonia nitrogen and nitrite nitrogen levels. By the end of the experiment, shrimp survival rates were above 86%, with no significant differences ( P > 0.05) among the three groups. Both weight gain rate and special growth rate tended to increase in the bioflocs treatments compared to those in the control. Meanwhile, the overall specific activities of protease, amylase, cellulase and lipase of the shrimp in the bioflocs treatments were all higher than those in the control; and for the specific activity of the same digestive enzyme, the differences between the bioflocs treatments and the control performed inconsistently among different organs: hepatopancreas, stomach and intestine. Present results suggest that the bioflocs can not only maintain favourable water quality conditions for shrimp culture and help shrimp grow well in zero-water exchange culture systems, but may also have a positive effect on digestive enzyme activities of the shrimp. [ABSTRACT FROM AUTHOR]

Numerous research has explored the associations of outdoor or indoor fine particulate matter (PM2.5) and health effects; however, few studies compared the effects of indoor PM2.5 originated from outdoor (PM2.5,os) and indoor sources (PM2.5,is). To assess the associations of PM2.5,os and PM2.5,is with cardiopulmonary function in patients with chronic obstructive pulmonary disease (COPD) and healthy elderly adults, blood pressure (BP) and pulmonary function were repeatedly examined in 43 COPD patients and their 32 healthy spouses in Beijing, China. Iron was used as tracer element to separate PM2.5,os and PM2.5,is. Mixed‐effects models were applied to assess the associations of PM2.5,os or PM2.5,is and health effects after controlling for potential confounders. There was a reduction in forced expiratory volume in first second (FEV1) in COPD patients associated with PM2.5,is during the heating season. PM2.5,os was positively associated with diastolic BP (DBP) in healthy elderly adults during the heating season. There was a reduction in peak expiratory flow (PEF) in healthy elderly adults associated with PM2.5,os during the non‐heating season. Exposure to indoor‐ and outdoor‐originated PM2.5 had different health effects on cardiopulmonary function in different populations. The results provide supporting evidence for improving indoor air quality to promote public health among susceptible population. [ABSTRACT FROM AUTHOR]

The specific and non-specific immune parameters and protection of European eels ( Anguilla anguilla) were evaluated after bathing eels with Aeromonas hydrophila. Two hundred eels were distributed into two equal groups and bathed with Phosphate-buffered saline (Control group) or 1.0 × 107 cfu mL−1 A. hydrophila (Test group) for 1 h respectively. Then, eels were bled aseptically from the caudal sinus on 1, 4, 7, 14 and 28 days post treatment. The blood cells were used to evaluate the cellular immunity and the serum was used to determine the titres of specific antibody as well as the activities of superoxide dismutase ( SOD) and lysozyme. Eels from both groups were challenged by intraperitoneal injection of 1.0 × 107 cfu of A. hydrophila on 28 and 42 days post bathing. The results show that eels bathed in A. hydrophila significantly ( P < 0.05) enhanced the proliferation of different types of blood cells and the serum titres of anti- A. hydrophila antibody. The Relative Percent Survival ( RPS) after challenge on 28 and 42 days post bathing in Test group vs. Control group was 40% and 50% respectively. These results suggest that bathing European eels in A. hydrophila would positively affect specific as well as non-specific immune parameters and protect against A. hydrophila infection in freshwater farming. [ABSTRACT FROM AUTHOR]