箱型矮栏养猪好

自1960年来,已建造了数千幢部分或全部漏缝地板的肥育猪舍,但每头肥育猪的空间有限,通常为O.54~O.64平方米.在西欧进行的比较试验证明,当采用部分漏缝地板,且每头猪有o.70平方米空间时,技术效益较好.而如果猪能在箱型矮栏里休息,效果就更佳好动的肥育猪一般不怕贼风或低温的影响.试验表明,把饲喂和排粪区与躺卧区分开,是很有利的.躺卧区三面能够关闭,并可用顶盖覆盖,以创造     

Nitrogen fixation in marine shipworms

Nitrogen fixation is associated with four shipworl species. A bacterium capable of fixing nitrogen under anaerobic conditions and of liquefying cellulose in culture has been isolated from the gut of one species. High fixation rates (up to 1.5 micrograms of nitrogen per milligram dry weight per hour), which resulted in a doubling of cellular nitrogen in as little as 1.4 days, was associated with Teredora malleolus from the Sargasso Sea. Three species from coastal waters were assayed, and of these juveniles showed the highest fixation rates. Nitrogen fixation activity appeared to be inversely related to the ability of shipworms to obtain combined-nitrogen compounds in their diet. It could be a significant source of nitrogen for shipwornms and perhaps other oceanic organisms that ingest terrestrial plant material.     

Economics of Brucella ovis control in sheep: computerized decision-tree analysis

The epidemiology and economics of Brucella ovis control in a hypothetical, commercial sheep flock (100 rams and 2,500 ewes) were investigated. The investigation consisted of an epidemiologic simulation model, reported in a companion paper, and a decision-tree analysis, reported here. It was predicted from the simulation model that B ovis could be eradicated successfully in 2 test periods (less than 1 year) from a flock by using intensive screening and culling. A computerized decision-tree program was used to determine the economically optimal control strategy among several alternatives. Two versions of the program were used to determine the optimal alternative, based on minimizing the expected monetary loss (deterministic) and minimizing the associated risk (stochastic). The economically optimal alternative was to screen the rams by means of palpation, semen testing, and ELISA prior to the mating season. Rams positive to any test were culled. After the mating season was completed, the optimal action was to use ELISA for the remaining rams and to cull all that were ELISA positive. The cost of this alternative was approximately $6,150, or less than one half the annual cost of a vaccination program ($12,800) or no program ($13,550). Continuing palpation and semen testing were considered worthwhile on the basis of detecting new cases of B ovis infection and in maintaining high flock fertility. Similarly, the cost of annual use of ELISA was small (approximately $100), compared with the potential cost of not detecting a new case of B ovis infection.     

Maximal predicted duration of viremia in bluetongue virus-infected cattle.

Central to the development of rational trade policies pertaining to bluetongue virus (BTV) infection is determination of the risk posed by ruminants previously exposed to the virus. Precise determination of the maximal duration of infectious viremia is essential to the development of an appropriate quarantine period prior to movement of animals from BTV-endemic to BTV-free regions. The objective of this study was to predict the duration of detectable viremia in BTV-infected cattle using a probabilistic modeling analysis of existing data. Data on the duration of detectable viremia in cattle were obtained from previously published studies. Data sets were created from a large field study of naturally infected cattle in Australia and from experimental infections of cattle with Australian and US serotypes of BTV. Probability distributions were fitted to the pooled empirical data, and the 3 probability distributions that provided the best fit to the data were the gamma, Weibull, and lognormal probability distributions. These asymmetric probability distributions are often well suited for decay processes, such as the time to termination of detectable viremia. The analyses indicated a > 99% probability of detectable BTV viremia ceasing after < or = 9 weeks of infection in adult cattle and after a slightly longer interval in BTV-infected, colostrum-deprived newborn calves.     

Intracranial meningioma with pulmonary metastasis in three dogs.

Extracranial metastasis of primary central nervous system neoplasms is uncommon and has not been described in the dog. We report the clincopathologic features of intracranial meningioma with pulmonary metastasis in three dogs (case No. 1: 13-year-old castrated male Boxer dog; case No. 2: 14-year-old spayed female Dachshund; case No. 3: 6-year-old spayed female German Shepherd Dog). Case No. 1 presented with ataxia, lethargy, vomiting, and leaning and falling to the right, and had a transient remission following radiation and corticosteroid therapy; case No. 2 had a history of seizures that were unresponsive to primidone, left-sided postural reaction deficits, ataxia, and circling to the right; case No. 3 had only intermittent episodes of vomiting Computed tomography of case Nos. 1 and 2 revealed peripherally located homogeneous contrast-enhancing intracranial masses. Postmortem examination revealed intracranial masses with single or multiple pulmonary nodules in all three cases. Histologically, the intracranial and pulmonary masses were meningotheliomatous meningiomas with atypical features including brain infiltration, necrosis, nuclear atypia, prominent nucleoli, and moderate cell density. All of the primary meningiomas had low mitotic rates. The current interest in early diagnosis and aggressive clinical/surgical management of canine patients with meningioma and other primary central nervous system neoplasms will likely result in an increased detection of extracranial metastases.     

Web-based, interactive simulation of an anesthesia machine

Gases are transparent and the piping layout in anesthesia machines is not obvious, making it hard to understand anesthesia machine function, potential failure modes, and recovery from faults. We experimented with an approach that simplified the layout of the anesthesia machine piping by removing extraneous details and making gases not only visible, but also color-coded. More than 15 anesthesia machine controls were represented by icons that a user can adjust by clicking on the icon with a pointing device and subsequently observing the effect of his/her intervention on anesthesia machine function in real time. We simulated two anesthesia machine failures and also supported non-English languages and non-US gas color codes. Further, we initiated an experiment in Web philanthropy by deliberately choosing to make the educational module accessible without charge and selected the Web as the preferred medium for dissemination of the Virtual Anesthesia Machine (VAM) viewable at http://www.anest.ufl.edu/vam . Originally designed for use in human anesthesiology, a significant percentage (about 30%) of the 54 000 international visitors, as tracked by an independent third-party Web traffic monitoring service, for the period 9/00–5/02, were from the veterinary field. VAM is being used as part of the curriculum in veterinary programs in the US and overseas and has been well received by the global anesthesia community (human and veterinary).     

Idiopathic cutaneous and renal glomerular vasculopathy of greyhounds

An idiopathic disease involving skin and occasionally kidneys was seen in kenneled and racing greyhounds. Hemorrhages, fibrinoid arteritis, thrombosis, and infarction with deep, slowly healing ulcers characterized the skin lesions. Peracute renal glomerular necrosis, particularly involving afferent arterioles with intravascular coagulation in glomerular capillaries were the distinctive findings in affected kidneys. A complex pathogenesis of this disorder was suspected in which genetic predisposition plays a prominent role.     

Update: prevalence of Salmonella in pork sausage

One hundred seventy-five samples of fresh pork sausage representing thirty-five different commercial brands from six different retail stores were examined for the presence of salmonellae by standard enrichment, plating, biochemical and serological techniques. Contamination levels varied from 0 to 50% among stores and from 0 to 28% among brands. Prior research implied reduced prevalence of salmonellae in fresh pork sausage; however, these results indicate no variation in prevalence since 1969.     

Control of a foot-and-mouth disease epidemic in Argentina

A major epidemic of foot-and-mouth disease affected Argentina during 2001. The epidemic was controlled by mass-vaccination of the national herd and movement restrictions. The median herd disease reproduction ratio (R_H) decreased significantly from 2.4 (before the epidemic was officially recognized) to 1.2 during the mass-vaccination campaign and <1 following the mass-vaccination campaign. The largest distance between two outbreaks was similar during (1905 km) and after (1890 km) the mass-vaccination. However, after mass-vaccination was completed, the proportion of herd outbreaks clustered decreased from 70.4% to 66.8%, respectively. Although a combination of vaccination and livestock-movement restrictions was effective in controlling the epidemic, 112 herd outbreaks occurred up to 6 months after the end of the mass-vaccination campaign. Mass-vaccination and movement restrictions might be an effective strategy to control FMD; however, the time taken to end large, national epidemics might be >1 year.