Commercial forest fertilization causes long-term residual effects in ground vegetation of boreal forests

Due to an increasing demand of forestry products, nitrogen (N) fertilization of coniferous forests may in the future become a standard silvicultural practice in parts of the boreal region that is not too remotely situated. Beside positive effects on productivity, forest fertilization may induce changes in species composition of the ground vegetation. More information on the magnitude of such side effects is needed to evaluate whether commercial forest fertilization is in accordance with principles of sustainable forestry and preservation of biodiversity.     

Estimating landscape resistance from habitat suitability: effects of data source and nonlinearities

Context

Conservation corridors must facilitate long-distance dispersal movements to promote gene flow, prevent inbreeding, and allow animals to shift ranges with climate change. Least-cost models are used to identify areas that support long-distance movement. These models rely on estimates of landscape resistance, which are typically derived from habitat suitability.

Objectives

We examine two key steps in estimating resistance from habitat suitability: choosing a procedure to estimate habitat suitability, and choosing a transformation function to translate habitat suitability into resistance.

Methods

We used linear and nonlinear functions to convert three types of habitat suitability estimates (from expert opinion, resource selection functions, and step selection functions) into resistances for elk (Cervus canadensis) and desert bighorn sheep (Ovis canadensis nelsoni). We evaluated the resulting resistance maps on an independent set of observed long-distance, prospecting movements.

Results

A negative exponential function best described the relationship between resistance values and habitat suitability for desert bighorn sheep indicating long-distance movers readily travel through moderately-suitable areas and avoid only the least suitable habitat. For desert bighorn sheep, all three suitability estimates performed better than chance, and resource and step selection functions outperformed expert opinion. For elk, all three suitability estimates performed the same as chance.

Conclusions

When designing corridors to facilitate long-distance movements of mobile animals, we recommend transforming habitat suitability into resistance with a negative exponential function. Use of an exponential transformation means that larger fractions of the landscape offer low resistance, allowing greater flexibility in where a corridor is located.

     

Manipulation of host hepatocytes by the malaria parasite for delivery into liver sinusoids

The merozoite stage of the malaria parasite that infects erythrocytes and causes the symptoms of the disease is initially formed inside host hepatocytes. However, the mechanism by which hepatic merozoites reach blood vessels (sinusoids) in the liver and escape the host immune system before invading erythrocytes remains unknown. Here, we show that parasites induce the death and the detachment of their host hepatocytes, followed by the budding of parasite-filled vesicles (merosomes) into the sinusoid lumen. Parasites simultaneously inhibit the exposure of phosphatidylserine on the outer leaflet of host plasma membranes, which act as "eat me" signals to phagocytes. Thus, the hepatocyte-derived merosomes appear to ensure both the migration of parasites into the bloodstream and their protection from host immunity.     

Incidence and breed predilection for dystocia and risk factors for cesarean section in a Swedish population of insured dogs

OBJECTIVES: To estimate the incidence and breed predilection for canine dystocia using data from insurance claims. The risk factors for cesarean section (CS) were assessed for bitches with dystocia. STUDY DESIGN: Retrospective, longitudinal study. SAMPLE POPULATION: Insurance claims records (1995-2002) from a Swedish animal insurance database (Agria), including approximately 200,000 bitches. METHODS: The overall incidence rate of dystocia in insured bitches was calculated by dividing the number of reimbursed dystocia claims with the number of dog years at risk. Subsequently, incidence rates were stratified by breed, region, and habitat. The proportion of bitches with a dystocia claim that had CS were calculated, and risk factors for CS were assessed using a logistic regression model. RESULTS: Between 1995 and 2002, 3894 (2%) of 195,931 Swedish bitches included in the study had a reimbursed insurance claim for dystocia. The overall incidence rate of dystocia was 5.7 cases/ 1000 dog years at risk. Some breeds like the Scottish terrier were at increased risk of dystocia. Among bitches with dystocia, 63.8% were treated by CS. CONCLUSION: Dystocia in the bitch is more common than reported earlier. The risk of developing dystocia varies by breed, and a high percentage (63.8%) of affected bitches undergo CS. Clinical Relevance- Breeders and veterinarians could use this information to better predict which bitches are likely to experience dystocia and/or CS.     

Isolation of Salmonella spp from the environment of dairies without any history of clinical salmonellosis

OBJECTIVE: To determine whether Salmonella spp could be isolated from the environment of free stall dairies in Wisconsin without any history of clinical salmonellosis and determine the serotype and antimicrobial susceptibility of any Salmonella isolates recovered from the environment. DESIGN: Cross-sectional study. STUDY POPULATION: 20 free stall dairies with no history of clinical salmonellosis. PROCEDURES: Dairy owners completed a questionnaire regarding management and production practices. Multiple swab samples were obtained from throughout the free stall facilities and submitted for bacterial culture for Salmonella spp. Odds ratios were calculated to compare herd-level risk factors between dairies from which Salmonella organisms were isolated and herds from which Salmonella organisms were not isolated. RESULTS: Salmonella organisms were isolated from 9 of the 20 (45%) dairies. Salmonella serotype Meleagridis was isolated from 4 dairies, S. Meleagridis and S. Kentucky were isolated from 2 dairies, S. Meleagridis and S. Cyprus were isolated from 1 dairy, S. Cerro was isolated from 1 dairy, and S. Corvallis was isolated from 1 dairy. All isolates were susceptible to all antimicrobial agents tested. None of the potential risk factors analyzed demonstrated a significant association with an increased likelihood of isolating Salmonella spp. CONCLUSIONS AND CLINICAL RELEVANCE: Environmental Salmonella contamination was demonstrated on free stall dairies with no history of clinical salmonellosis.     

Characterization of the bacterial population of the genital tract of adult cats

OBJECTIVE: To characterize the bacteria of the genital tract in adult cats; assess the effect of estrus, mating, and administration of progestins on those microorganisms in females; and evaluate whether results of bacteriologic culture of vaginal swabs are affected by cleansing of the vulva prior to sampling or by repeated sampling. ANIMALS: 66 female and 29 male cats undergoing routine ovariohysterectomy or castration. PROCEDURE: Specimens were obtained from vaginal and uterine or preputial mucosae with swabs moistened with sterile saline (0.9% NaCl) solution. In 9 cats, vaginal specimens were obtained before and after cleansing of the vulva with ethanol; in 7 female cats, 2 vaginal speci mens were obtained in immediate succession. RESULTS: Aerobic bacteria were most commonly isolated from cats' vaginas and prepuces; anaerobic bacteria were isolated frequently from males (41%) but rarely from females (5%). Generally, culture results were not affected by cleansing of the vulva or repeated vaginal sampling. The bacterial population of the vaginas of cats was influenced by stage of the estrous cycle but not by mating or administration of progestins. Bacteria were not isolated from the uterus of any cat. CONCLUSIONS AND CLINICAL RELEVANCE: In cats, bacteria of the genital tract in females are predominantly aerobic; in males, aerobic and anaerobic bacteria are found. The bacterial population of the vagina is affected by stage of the estrous cycle. Pure growth of bacteria in culture of genital tract specimens is a normal finding; antimicrobials should only be administered if clinical signs of genital infection are present.     

Cardiac troponin I in feline hypertrophic cardiomyopathy

Measurement of plasma cardiac troponin I concentration ([cTnI]) is a sensitive and specific means for detecting myocardial damage in many mammalian species. Studies have shown that [cTnI] increases rapidly after cardiomyocyte injury. The molecular structure of cTnl is highly conserved across species, and current assays developed for its detection in humans have been validated in many species. In this study, [cTnI] was quantified using a 2-site sandwich assay in plasma of healthy control cats (n = 33) and cats with moderate to severe hypertrophic cardiomyopathy (HCM) (n = 20). [cTnI] was significantly higher in cats with HCM (median, 0.66 ng/mL; range, 0.05-10.93 ng/mL) as compared with normal cats (median, <0.03 ng/mL; range, <0.03-0.16 ng/mL) (P < .0001). An increase in [cTnI] was also highly sensitive (sensitivity = 85%) and specific (specificity = 97%) for differentiating cats with moderate to severe HCM from normal cats. [cTnI] was weakly correlated with diastolic thickness of the left ventricular free wall (r2 = .354; P = .009) but not with the diastolic thickness of the interventricular septum (P = .8467) or the left atrium: aorta ratio (P = .0652). Furthermore, cats with congestive heart failure at the time of cTnI analysis had a significantly higher [cTnI] than did cats that had never had heart failure and those whose heart failure was controlled at the time of analysis (P = .0095 and P = .0201, respectively). These data indicate that cats with HCM have ongoing myocardial damage. Although the origin of this damage is unknown, it most likely explains the replacement fibrosis that is consistently identified in cats with moderate to severe HCM.     

Behavioral needs of the transition cow and considerations for special needs facility design.

Improved building designs come from a better understanding of the behavioral needs of the dairy cow. The costs to provide for these needs in the facility must be offset by improved milk production, health, and longevity. Research is still required to more fully understand the health implications of many building design considerations and their impact on disease. Perhaps the most important end result of an improved environment for the transition cow, however, is an improvement in animal well-being. Better buildings that accommodate the behavioral needs of cows present "win-win" situations where dairy cattle thrive and work is more enjoyable. This results in an improved image for the industry, greater consumer confidence in the quality and safety of the final food product, and a prosperous dairy industry.