Effects of atropellis canker and stalactiform blister rust on the bending strength and stiffness of lodgepole pine lumber

Summary This study investigated the effect of Atropellis canker,Atropellis piniphila (Weir) Lohman and Cash, and stalactiform blister rust,Cronartium coleosporioides Arth., on the bending strength and stiffness of lumber from lodgepole pine,Pinus contorta Dougl. var.latifolia Engelm. The modulus of rupture, was unaffected by either disease. However, the modulus of elasticity (MOE) of lumber from infected trees, as determined by the Cook Bolinders and static bending tests, was significantly reduced from those of healthy trees. This impact should affect the use of lumber from infected trees when serviceability criteria govern the design of a structure. Should MOE-based, machine stress-rating of lumber become standard in the future, there may be an adverse, stress-related impact of these diseases on lumber value.We thank Mr. D. Hutcheson, B.C. Forest Service, Kamloops Region for advice and assistance, Messers, T. Jeanes, B. Geiselmann and D. Crabtree, Balco Forest Products Ltd., for advice, assistance, and particularly for harvesting and manufacture of the test material; Mr. L. Olsen, Forintek Canada Ltd. for assistance, and Dr. A. Harestad, Simon Fraser University for critical review. The research was supported in part by the Natural Sciences and Engineering Research Council, Canada, Operating Grant No. A3881     

Mastitis diagnostics and performance monitoring: a practical approach

In this paper a review is given of frequently used mastitis diagnostic methods in modern dairy practice. Methods used at the quarter, cow, herd and regional or national level are discussed, including their usability for performance monitoring in udder health. Future developments, such as systems in which milk-derived parameters are combined with modern analytical techniques, are discussed. It is concluded that, although much knowledge is available and science is still developing and much knowledge is available, it is not always fully exploited in practice.     

Prevalence and herd-level risk factors for intramammary infection with coagulase-negative staphylococci in Dutch dairy herds

In this study, the prevalence of intramammary infection (IMI) with coagulase-negative staphylococci (CNS) in The Netherlands was estimated on 49 randomly selected herds with at least 40 lactating cows. In total, 4220 quarter milk samples were collected. The prevalence of CNS IMI in The Netherlands was estimated at 10.8% at quarter level and 34.4% at cow level, making it the most frequently isolated group of pathogens. Fourteen species of CNS were identified; the most frequently isolated species was Staphylococcus chromogenes (30.3%) followed by Staphylococcus epidermidis (12.9%) and Staphylococcus capitis (11.0%). Prevalence of CNS IMI was higher in heifers compared to older cows. Geometric mean quarter SCC of CNS-positive quarters was 109,000 cells/ml, which was approximately twice as high as culture-negative quarters. Quarters infected with S. chromogenes, S. capitis and Staphylococcus xylosus had a higher SCC (P<0.05) than culture-negative quarters, while quarters that were culture-positive for S. epidermidis and Staphylococcus hyicus tended to have a higher SCC than culture-negative quarters. An increased prevalence of CNS IMI was associated with the herd-level variables source of drinking water not being tap water, housing of dry cows in one group instead of multiple groups, measurement of cow SCC every month, udder health monitoring by the veterinarian, pasturing during outdoor season, percentage of stalls contaminated with milk, and BMSCC>250,000 cells/ml. Although a causal relation between these factors and prevalence of CNS is not proven and for some factors not even likely, knowledge of the associations found may be helpful when approaching CNS problems on dairy farms.     

Cost estimation of heifer mastitis in early lactation by stochastic modelling

Heifer mastitis, reflected by an elevated somatic cell count (SCC) in early lactation (SCCel), results in a decreased milk production, a higher risk for subclinical and clinical mastitis during lactation, and an elevated culling hazard. The aims of this study were to calculate the costs of heifer mastitis defined as an elevated SCC in early lactation, and to show the variation of these costs in the Dutch/Belgian dairy sector. A stochastic model, in which the variation and uncertainty of heifer mastitis are taken into the account, was developed with input data from literature and expertise. Costs were estimated, using default values. The mean costs for an elevated SCCel that cured were on average euro 13/heifer present on a farm (range: euro 0-118), for an elevated SCC at calving proceeding in subclinical mastitis on average euro 5/heifer present on a farm (range: euro 0-euro 82), and for a clinical heifer mastitis case associated with an elevated SCC after calving on average euro 270. On average this results in euro 13/heifer present on a farm (range: euro 0-137). Combined, these three cost aspects result in a total cost of on average euro 31/heifer present on a farm (range: euro 0-220). The large variation in the costs is very important regarding farm management and farm support. The difference in costs reflects also the difference in room for investment. When the costs that can be prevented are estimated at farm level, these data can be of help in setting goals in herd health advice and farm management.     

Proportion of individuals with anti-Batrachochytrium dendrobatidis skin bacteria is associated with population persistence in the frog Rana muscosa

The emergence of the infectious disease chytridiomycosis is a major factor responsible for amphibian extinctions in pristine habitats. However, some populations coexist with Batrachochytrium dendrobatidis (Bd), the agent of chytridiomycosis, and others go extinct when Bd arrives. Variation of pathogen severity among populations may be explained by differences of antimicrobial skin peptides and anti-Bd skin bacteria. Previous work showed that a population of the frog Rana sierrae had a high proportion of individuals with at least one species of cultured anti-Bd skin bacteria and was coexisting with Bd for more than 6 years. A population of the closely related sister species Rana muscosa had a significantly lower proportion of individuals with anti-Bd bacteria, and the following year, it went extinct due to Bd. We extended previous work to include another sampling of the R. sierrae population coexisting with Bd and found that, although the anti-Bd bacterial community somewhat differed, both populations had a high proportion of individuals with antifungal bacteria. We also included a population of R. muscosa that was naïve of Bd and predicted to go extinct once Bd emerged since that was the fate of neighboring populations. However, the naïve R. muscosa population had a high proportion of antifungal bacteria, which suggested that the population might survive if Bd emerged. Two years later, the population was surviving with Bd endemic. Variation in the proportion of individuals with anti-Bd skin bacteria appears to explain why some populations persist when Bd emerges in a population.     

Chemotaxis in Mycoplasma gallisepticum

Boyden-type chemotactic chambers were used to demonstrate that Mycoplasma gallisepticum (MG) was capable of migrating into chemotactic membranes. Scanning electron microscopy was used to confirm that MG could penetrate the membranes. To further demonstrate the invasive ability of MG, MG was deposited on the shell membranes of 9-day-old chicken embryos, and after 6 days of incubation, the presence of MG DNA in the allantoic fluids was detected by polymerase chain reactions. These results indicate that MG can penetrate cellular membrane, possibly by going through the porous cellular surface.     

Mycoplasma meleagridis-induced lesions in the tarsometatarsal joints of turkey embryos

Mycoplasma meleagridis (MM) has the ability to cause bone deformity in turkey poults. However, few pathological lesions have been described and no evidence of MM-induced damage to the bones has been shown. In this study, 17-day-old turkey embryos were inoculated with MM into the allantoic cavity. On the 27th day, eight of the 22 embryos presented with curved toes. Scanning electron microscopy of the tarsometatarsal joints showed fissures in the cartilage. Histological sections of the joints revealed only the infiltration of cells with eosinophilic granules. Immunohistochemical staining (IHS) showed the presence of MM in the aggregates of the bone marrow cells and the cells with eosinophilic granules. Some of these cells were harvested by laser capture microdissection (LCM), lysed, and used as template DNA. With a pair of MM-specific primers in a conventional polymerase chain reaction (PCR), a gene product was amplified, and it comigrated with the MM DNA, which indicates that these captured cells contained MM DNA. Thus, this research shows that inoculation of MM into the turkey embryos produced joint lesions and caused cellular infiltration within the bones.     

Morphologic changes in chicken cells after in vitro exposure to Mycoplasma gallisepticum

Mycoplasma gallisepticum (MG) was used to expose chicken peripheral blood lymphocytes (PBLs), red blood cells (RBCs), heterophils, and chicken tumor cells (MSB-1 and HD-11 cells). Incubation of PBLs with MG for 3 hr resulted in extensive clumping of lymphocytes. Incubation of the MSB-1 cells with MG also caused clumping of the cells, with many of the cells showing perforations and others showing capping of the surface projections. Incubation of RBCs with MG resulted in an altered cell surface morphology, a decrease in cell size, and perforation. There were no discernible changes on the surface of the heterophils and the HD-11 cells. However, the HD-11 cells appeared to have a decreased ability to attach to the surface of the plastic and to have a decreased ability to respond to chemoattractant fMLP after 24 hr of incubation. These results suggest that, under the conditions used, MG caused certain damage to peripheral blood cells and a significant decrease in chemotactic response in the HD-11 cells.     

The immunostimulatory activity and stability of grass carp (Ctenopharyngodon idellus) roe lectin

A hexameric rhamnose-specific lectin with a molecular mass of 205kDa and exhibiting some N-terminal sequence similarity to other fish lectins was isolated from roe of the grass carp (Ctenopharyngodon idellus) by affinity chromatography on rhamnose-Sepharose and ion exchange chromatography by fast protein liquid chromatography on a Mono S column. The lectin exhibited mitogenic activity toward murine splenocytes with a potency lower than that of the plant lectin ConA. It exerted a stimulatory effect at a concentration of 10 micro g/ml on the phagocytic activity of seabream (Sparus sarba) macrophages. It was unstable toward heat (temperature > or =40 degrees C), acid (0.1M HCl), alkali (0.1M NaOH), trypsin and succinylation.     

Mycoplasma mastitis in dairy cattle

The most important characteristics of Mycoplasma mastitis on dairy farms are described, based on two case studies. Clinical symptoms, diagnostics, epidemiology, and a plan of action are presented. In the herds investigated, Mycoplasma mastitis was characterized by multiple affected quarters unresponsive to treatment with antibiotic and/or anti-inflammatory agents. Most striking were a sandy sediment, brown colouring, and rice-like structure of the milk of affected animals. Clinical symptoms differed in the two affected herds. Diagnosis was based on bacteriological investigation of samples of milk and synovial fluid taken from infected cows. Affected animals were culled immediately, and the herds were monitored by repeated testing of bulk milk samples. It was concluded that a consequence of the increasing size of cattle herds in the Netherlands is that subclinical/clinical Mycoplasma mastitis may be diagnosed more frequently than in the past. In the case of Mycoplasma mastitis, farmers and veterinary practitioners are advised to draw up a plan of action together, incorporating aspects such as diagnostics at cow level, direct culling of affected animals, hygiene during milking, including post-milking teat disinfection, and routine monitoring of bulk milk. Unpasteurized milk should not be given to calves.