Effect of rice growth stages and silicon on sheath blight development

ABSTRACT The objective of this study was to determine the effect of silicon (Si) and rice growth stages on tissue susceptibility to sheath blight (Rhizoctonia solani Kühn) under controlled conditions. Rice plants (cv. Rio Formoso) were grown in pots containing low-Si soil amended with Si at 0, 0.48, 0.96, 1.44, and 1.92 g pot(-1) and inoculated with R. solani at the following days after emergence: 45 (four-leaf stage), 65 (eight-leaf stage), 85 (tillering), 117 (booting), and 130 (panicle exsertion). For plants inoculated with R. solani at all growth stages, Si concentration in straw increased as rate of Si increased from 0 to 1.92 g pot(-1). Concentration of calcium in the straw did not differ among plant growth stages. Although incubation period was not affected by the amount of Si added to the soil, this variable was shorter at booting and panicle exsertion stages. As the rates of Si increased in the soil, the total number of sheath blight lesions on sheaths and total area under the relative lesion extension curve decreased at all plant growth stages. The severity of sheath blight was lower at booting and panicle exsertion stages as the rates of Si increased in the soil. In general, plants grown in Si-nonamended pots and inoculated with R. solani were more vulnerable to infection at all growth stages, but especially at 45 days after emergence. Plant dry weights for inoculated plants increased as the Si rates increased from 0 to 1.92 g pot(-1). The greatest dry weight increases occurred for plants inoculated at booting and panicle exsertion stages. Si fertilization is a promising method for controlling sheath blight in areas where soil is Si deficient and when cultivars that exhibit an acceptable level of resistance to sheath blight are not available for commercial use.     

Benefits of prophylactic gastropexy for dogs at risk of gastric dilatation-volvulus

The lifetime probability of death from gastric dilation–volvulus (GDV) for five dog breeds was estimated based on published breed-specific longevity and GDV incidence. These breeds were Great Dane, Irish Setter, Rottweiler, Standard Poodle and Weimaraner. Lifetime risk (95% CI) of GDV in these breeds ranged from 3.9% (0–11.2%) for Rottweiler to 36.7% (25.2–44.6%) for Great Dane.

A decision-tree analysis for prophylactic gastropexy—using lifetime probability of death from GDV and expected cost savings for veterinary services as outcome measures—was undertaken to determine the preferred course of action in several dog breeds. Prophylactic gastropexy was the preferred choice of action for all breeds examined, with the reduction in mortality (versus no gastropexy) ranging from 2.2-fold (Rottweiler) to 29.6-fold (Great Dane). Assuming a prophylactic gastropexy costs US$ 400, the procedure was cost-effective when the lifetime risk of GDV was ≥34%. The maximum and minimum estimated breakeven costs for the gastopexy procedure ranged from US$ 20 (Rottweiler) to US$ 435 (Great Dane). The cost-effectiveness of prophylactic gastropexy was most sensitive to the cost of treating GDV (US$ 1500). Prophylactic gastropexy raises ethical issues that need to be considered by veterinarians and dog breeders.     

Evaluation of antithyroglobulin antibodies after routine vaccination in pet and research dogs

OBJECTIVE: To determine whether routine vaccination induces antibodies against bovine thyroglobulin and autoantibodies against canine thyroglobulin in dogs. DESIGN: Prospective study. ANIMALS: 20 healthy research Beagles and 16 healthy pet dogs. PROCEDURE: For the research Beagles, 5 dogs were vaccinated with a multivalent vaccine and a rabies vaccine, 5 dogs received only the multivalent vaccine, 5 dogs received only the rabies vaccine, and 5 dogs were unvaccinated controls. The multivalent vaccine was administered at 8, 10, 12, 16, 20, 26, and 52 weeks of age and every 6 months thereafter. The rabies vaccine was administered at 16 and 52 weeks of age and then once per year. Blood was collected from all dogs at 8, 16, and 26 weeks of age and then 4 times yearly. Assays for antibodies directed against bovine and canine thyroglobulin were performed prior to and 2 weeks after each yearly vaccination. For the pet dogs, blood was collected prior to and 2 weeks after 1 vaccination. RESULTS: In the research Beagles, there was a significant increase in anti-bovine thyroglobulin antibodies in all vaccinated dogs, compared with control dogs. There was a significant increase in anti-canine thyroglobulin antibodies in the 2 groups of dogs that received the rabies vaccine but not in the group that received the multivalent vaccine alone. In the pet dogs, there was a significant increase in anti-canine thyroglobulin antibodies after vaccination but no significant change in anti-bovine thyroglobulin antibodies. CONCLUSIONS AND CLINICAL RELEVANCE: Recent vaccination may result in increased anti-canine thyroglobulin antibodies. Whether these antibodies have a deleterious effect on canine thyroid function is unknown.     

Sensitivity of test strategies used in the Voluntary Johne's Disease Herd Status Program for detection of Mycobacterium paratuberculosis infection in dairy cattle herds

OBJECTIVE: To evaluate sensitivities at the herd level of test strategies used in the Voluntary Johne's Disease Herd Status Program (VJDHSP) and alternative test strategies for detecting dairy cattle herds infected with Mycobacterium paratuberculosis. DESIGN: Nonrandom cross-sectional study. SAMPLE POPULATION: 64 dairy herds from Pennsylvania, Minnesota, Colorado, Ohio, and Wisconsin. Fifty-six herds had at least 1 cow shedding M. paratuberculosis in feces; the other 8 herds were free from paratuberculosis. PROCEDURE: For all adult cows in each herd, serum samples were tested for antibodies to M. paratuberculosis with an ELISA, and fecal samples were submitted for bacterial culture for M. paratuberculosis. Sensitivities at the herd level (probability of detecting infected herd) of various testing strategies were then evaluated. RESULTS: Sensitivity at the herd level of the testing strategy used in level 1 of the VJDHSP (use of the ELISA to test samples from 30 cows followed by confirmatory bacterial culture of feces from cows with positive ELISA result) ranged from 33 to 84% for infected herds, depending on percentage of cows in the herd with positive bacterial culture results. If follow-up bacterial culture was not used to confirm positive ELISA results, sensitivity ranged from 70 to 93%, but probability of identifying uninfected herds as infected was 89%. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that the testing strategy used in the VJDHSP will fail to identify as infected most dairy herds with a low prevalence of paratuberculosis. A higher percentage of infected herds was detected if follow-up bacterial culture was not used, but this test strategy was associated with a high probability of misclassifying uninfected herds.     

An analysis of structure of tree seedling populations on a Lahar

The structure of a tree seedling population is dependent on the interaction of several processes including seed dispersal, germination, survival, and competition on a physical landscape. Structural components (composition, size distributions, spatial distributions, age distributions, density, and history) of a tree seedling population on the Muddy River Lahar on the east side of Mount St. Helens were examined over a range of extents (1/10 m to 1000 m). Many of these component have rarely been examined at the larger extents listed here. Composition reflected distances to seed source and seed morphology. Seedling sizes are inversely proportional to depth to a buried soil if one existed. Spatial patterns indicated that seedling are clustered for tree seedlings less than 200 m apart, random for tree seedling from 200 m to 400 m and uniform for seedling greater than 400 m apart. This was confirmed by two measures of multidimensional spatial point pattern. Age distributions did not reflect the size distributions; old seedlings could be almost any size, young seedlings were constrained to be small in size. Densities appear to be typical for forests in the area. History of disturbance events (the lahar establishment, and successive ash, pumice, and erosion) has strongly influenced this tree seedling community.     

Effect of sodium bicarbonate on racing Standardbreds

Twenty-two Standardbred horses in race training were used in a crossover experiment to determine the effect of oral sodium bicarbonate (NaHCO3) administration on performance and metabolic responses to a 1.6-km (1-mile) race. Horses were paired and one horse in each pair was treated with either NaHCO3 (300 mg/kg BW) or a placebo, 2.5 h before they raced against each other. Each horse was scheduled to compete in two races, approximately 1 wk apart, one on each treatment. Horses always raced in the same pairs. Fourteen horses successfully completed both races. Jugular blood samples were obtained 1.5 h after treatment (rest), immediately before racing, 5 min post-race and 15 min post-race. In six horses, blood samples also were obtained 30 min post-race. Race times averaged 1.1 s faster after NaHCO3 treatment (P less than .1). Sodium bicarbonate treatment also elevated blood pH (P less than .05). In the horses sampled 15 and 30 min post-race, blood lactate disappearance was faster with the NaHCO3 treatment (P less than .05). The NaHCO3 may delay the fatigue precipitated by i.m. acidosis. Because other factors may limit performance (musculoskeletal soundness, cardiovascular and respiratory ability), NaHCO3 would not be expected to enhance the performance of all horses. However, the effect of NaHCO3 on lactate clearance may have implications for all intensively worked horses; because lactate and the associated hydrogen ions are believed to cause muscle damage and soreness, any mechanism to increase their removal rate could benefit the equine athlete.     

The influence of regulatory forest policy tools on biodiversity measures for forests in Ukraine

The transition from a state-oriented forest economy to a market-oriented one requires a critical analysis of the set of tools designed to implement state forest policies. One of the important goals of Ukrainian forest policy is conservation of the biodiversity of forest ecosystems. This paper analyzes the influence of two of the regulatory forest policy instruments (zoning and prohibition of final harvesting) on the diversity of woody vegetation using Tobit regression. Data on the forest resources of the Sumy administrative province in Ukraine are used for the analysis. Additionally, we look at how diversity of woody vegetation is affected by the form of forest tenure.     

One-day rate measurements for estimating net nitrification potential in humid forest soils

Measurements of net nitrification rates in forest soils have usually been performed by extended sample incubation (2–8 weeks), either in the field or in the lab. Because of disturbance effects, these measurements are only estimates of nitrification potential and shorter incubations may suffice. In three separate studies of northeastern USA forest soil surface horizons, we found that laboratory nitrification rates measured over 1 day related well to those measured over 4 weeks. Soil samples of Oa or A horizons were mixed by hand and the initial extraction of subsamples, using 2 mol L⁻¹ KCl, occurred in the field as soon as feasible after sampling. Soils were kept near field temperature and subsampled again the following day in the laboratory. Rates measured by this method were about three times higher than the 4-week rates. Variability in measured rates was similar over either incubation period. Because NO₃⁻ concentrations were usually quite low in the field, average rates from 10 research watersheds could be estimated with only a single, 1-day extraction. Methodological studies showed that the concentration of NH₄⁺ increased slowly during contact time with the KCl extractant and, thus, this contact time should be kept similar during the procedure. This method allows a large number of samples to be rapidly assessed.