高致病性猪繁殖与呼吸综合征病毒引发高热综合征病因分析与防治措施

通过市场调研，分析了猪高致病性猪繁殖与呼吸综合征病毒引起高热综合征的发病原因，提出防治措施，以供广大养殖户参考。     

Establishing the need for an engineering standard for agricultural hitch pins

Documented incidents have occurred in which failure or unintentional disengagement of agricultural hitch pins has contributed to property damage and personal injury. An examination of current hitch pin use on a convenience sample of farm operations in Indiana revealed a variety of non-standard, worn and damaged, and inappropriately sized hitch pins in use. Informal interviews with the farm operators confirmed that hitch pin misuse, failure, or disengagement is a relatively widespread problem that remains largely unaddressed. On-site observations also suggested a low use of hitch pin retaining devices or safety chains. A review of prior research revealed that little attention has been given to this problem, and currently no documentation allows for an estimate of the frequency or severity of losses associated with hitch pin misuse, failure, or disengagement. No specific engineering standards were found that directly applied to the design, appropriate selection, or loading capacity of agricultural hitch pins. Major suppliers of replacement hitch pins currently provide little or no information on matching hitch pin size to intended applications, and most replacement hitch pins examined were of foreign origin, with the overwhelming majority imported from China or India. These replacement hitch pins provided no specifications other than diameter, length, and, in some cases, labeling that indicated that the pins had been "heat treated. " Testing of a sample of 11 commercially available replacement hitch pins found variation along the length of the pin shaft and between individual pins in surface hardness, a potential predictor of pin failure. Examination of 17 commercially available replacement pins also revealed a variety of identifiers used to describe pin composition and fabrication methods, e.g., "heat treated." None of the pins examined provided any specifications on loading capacity. It was therefore concluded that there is a need to develop an agricultural hitch pin engineering standard that would reflect current agricultural applications and practices and that would be promoted to both original equipment manufacturers and manufacturers and suppliers of replacement hitch pins. The standard should address the design of composite pins, heat treating, surface hardening, loading capacity and labeling of such, incorporation of unintentional disengagement prevention devices, indicators of the need for replacement due to wear, and safety information that should be included in operator instructions. ASABE is the most appropriate organization to develop such a standard. It was also concluded that agricultural safety and health programs and professionals need to raise the awareness of farmers concerning the appropriate selection and use of agricultural hitch pins, including the need to replace non-standard pins with pins less likely to fail or disengage during use, the need to replace hitch pins with indications of potential failure, and the importance of using appropriate safety chains, especially during transport of equipment behind tractors and trucks on public roads.     

High-Energy Charged Particles in the Innermost Jovian Magnetosphere

The energetic particles investigation carried by the Galileo probe measured the energy and angular distributions of the high-energy particles from near the orbit of Io to probe entry into the jovian atmosphere. Jupiter's inner radiation region had extremely large fluxes of energetic electrons and protons; intensities peaked at approximately2.2RJ (where RJ is the radius of Jupiter). Absorption of the measured particles was found near the outer edge of the bright dust ring. The instrument measured intense fluxes of high-energy helium ions (approximately62 megaelectron volts per nucleon) that peaked at approximately1.5RJ inside the bright dust ring. The abundances of all particle species decreased sharply at approximately1.35RJ; this decrease defines the innermost edge of the equatorial jovian radiation.     

Use of the Anemon Index to evaluate the quality of analgesia during fentanyl and sevoflurane anaesthesia in pigs

Anemon I is a new monitoring system that can be used to evaluate autonomic nervous system reactivity in real time by showing a simple, easily interpretated quantitative index (0–200), the Anemon Index (AI) ( Junke et al. 2000 ). This study used the AI to evaluate the quality of analgesia during sevoflurane and fentanyl anaesthesia in pigs. Six healthy pigs, weighing 24.76 ± 3.40 kg, were induced to anaesthesia with 5% sevoflurane (SEVO) in 5 L minute^?1 oxygen. After endotracheal intubation SEVO was given at 1 MAC (2.66%) in 3 L minute^?1 oxygen. Fentanyl was infused IV at 50 µg kg^?1 hour^?1 for the first 30 minutes of anaesthesia, discontinued for 30 minutes, and then infused at 100 µg kg^?1 hour^?1 for another 30 minutes. Three mechanical noxious stimuli (needle prick, pin‐prick and pressure on the abdomen) were applied for 15 seconds at 30, 60 and 90 minutes. The AI, ECG, invasive mean arterial blood pressure (MAP), heart rate (HR), SpO₂ by pulse oximetry, tidal volume, Fe′sevo , Fe ′CO₂ and respiratory rate were recorded before induction (baseline), after induction, after intubation and extubation, and before and during noxious stimulation at 30, 60 and 90 minutes. Recovery times were recorded. Statistically significant differences were determined by anova . Spearman rank‐correlation was used to evaluate the relationship between AI and hemodynamic variables. A p‐value of < 0.05 was considered significant. A significant (p < 0.01) decrease in AI was recorded after anaesthetic induction, from 82.3 ± 21.1 to 52.7 ± 20.3. After intubation, AI increased slightly, but not significantly, to 71.7 ± 27.1. A significant (p < 0.05) increase of AI occurred after extubation. Nociceptive stimuli did not have any measurable effect either on AI or on recorded cardiovascular variables. There was no movement, respiratory changes, or any other visible response to noxious stimulation. The AI did not change significantly with the different doses of fentanyl. Respiratory depression and apnoea were seen in all animals during the fentanyl infusion; therefore, pigs received intermittent positive pressure ventilation. Anaesthesia with sevoflurane and fentanyl resulted in a significant (p < 0.001) decrease in MAP. Heart rate did not change significantly. There was no correlation between AI and cardiovascular variables (HR and MAP). Endotracheal intubation caused an increase and extubation a greater significant increase in the AI. This suggests that intubation and extubation may represent stressful events during general anaesthesia, although further studies are needed to validate the use of the AI in pigs. Sevoflurane anesthetic induction may not prevent the sympathetic stimulus caused by endotracheal intubation in pigs, as indicated by the increased AI values.     

Evaluation of Trypsin Treatment on the Inactivation of Bovine Herpesvirus Type 1 on In Vitro Produced Pre-implantation Embryos

The aim of this study was to evaluate the efficiency of trypsin treatment on the inactivation of bovine herpesvirus type 1 (BoHV-1) on in vitro produced by fertilization and artificially infected bovine embryos. Bovine embryos on day 7 were exposed with 10 μl of BoHV-1, Los Angeles strain 10^7.5 TCID. These embryos and control embryos were divided in two groups: submitted to the sequential washes or to the trypsin treatment according to the International Embryo Transfer Society (IETS) guidelines. The embryos and the last washing drop of each group were used as inoculum to infect Madin Darby bovine kidney (MDBK) cells and submitted to nested PCR reaction using the primer that encodes the gene conserved region of virus glycoprotein gB. The data have shown that the control embryos and their last washing drop were negative. The exposed embryos that were treated with trypsin have shown positive results on the n-PCR and MDBK culture, and their last washing drop were negative. Our data have demonstrated that the trypsin treatment was not able to eliminate the BHV-1 of the embryos, suggesting an interaction between virus and embryo.     

Rapid development of enhanced atrazine degradation in a Dundee silt loam soil under continuous corn and in rotation with cotton

Mississippi Delta cotton (Gossypium hirsutum L.) production in rotation with corn (Zea mays L.) was evaluated in field experiments from 2000 to 2005 at Stoneville, Mississippi. Plots maintained under minimum tillage were established in 2000 on a Dundee silt loam with treatments including continuous cotton or corn and alternate cotton-corn rotations. Mineralization and dissipation of 14C [ring]-labeled atrazine were evaluated in the laboratory on soils collected prior to herbicide application in the first, second, third, and sixth years of the study. In soils collected in 2000, a maximum of 10% of the atrazine was mineralized after 30 days. After 1 year of herbicide application, atrazine-treated soils mineralized 52-57% of the radiolabeled atrazine in 30 days. By the sixth year of the study, greater than 59% of the atrazine was mineralized after 7 days in soils treated with atrazine, while soils from plots with no atrazine treatment mineralized less than 36%. The data also indicated rapid development of enhanced atrazine degradation in soils following 1 year of corn production with atrazine use. Atrazine mineralization was as rapid in soils under a rotation receiving biannual atrazine applications as in soils under continuous corn receiving annual applications of atrazine. Cumulative mineralization kinetics parameters derived from the Gompertz model (k and ti) were highly correlated with a history of atrazine application and total soil carbon content. Changes in the soil microbial community assessed by total fatty acid methyl ester (FAME) analysis indicated significant interactions of cropping system and sampling date, with FAME indicators for soil bacteria responsible for differences in community structure. Autoclaved soil lost all ability to mineralize atrazine, and atrazine-mineralizing bacteria were isolated from these plots, confirming the biological basis for atrazine mineralization. These results indicate that changes in degradative potential of a soil can occur rapidly and some changes in soil properties may be associated with cropping systems, which can contribute to enhanced atrazine degradation potential.