Threshold values for chemical control of powdery mildew (Erysiphe cruciferarum) on Brussels sprouts

To establish control thresholds for chemical control of powdery mildew (Erysiphe cruciferarum) on Brussels sprouts, mildew intensity on leaves and buds was observed on the cultivars Lunet, Tardis and Asgard during three years in unsprayed plots. Mildew infection on the leaves was observed from late August onwards, increasing to moderate or high levels. In one year light infestation of the buds was observed, but no reduction in quality occurred. These preliminary results indicate, that from late August onwards the following levels of leaf injury by powdery mildew can be tolerated: T=5+0.42^*(Julian date — 235), in which T is the tolerable leaf injury in percentage leaf area covered. When sampling the crop to assess powdery mildew infection, care must be taken that leaves are sampled from all stem positions, as top leaves tend to be much less infected.     

Methyl bromide in natural fresh waters: Hydrolysis and volatilisation

The effect of some physical factors on the processes (hydrolysis, volatilisation) regulating the persistence of methyl bromide in fresh surface waters was investigated to complement previous research. It has been confirmed that electromagnetic radiation in the visible field has no influence on the hydrolysis kinetics of the fumigant. The removal of methyl bromide by volatilisation from stirred and ventilated solutions appears to be of greater importance in practice. It has been shown that under these conditions the half-life is directly proportional to the liquid depth. Without stirring volatilisation is greatly reduced, due to the low diffusivity of methyl bromide in the aqueous phase.     

Field evaluation of the single intradermal cervical tuberculin test and the interferon-gamma assay for detection and eradication of bovine tuberculosis in Spain

A field comparison of the interferon-gamma (IFN-gamma) assay and the single intradermal cervical tuberculin (SICT) test for the diagnosis of bovine tuberculosis was conducted. A total of 1136 cattle belonging to 85 herds placed in 'Castilla y León' (northwestern Spain) were chosen, and 21 of these herds were subjected to the diagnostic assays two or three times at intervals of at least 4 months. All the animals positive to any of the tests were slaughtered and tuberculosis was confirmed by culture isolation method (CIM) and further identification by means of PCR. Only 10.6% of cattle reacted with the bovine PPD in the SICT test, a percentage that increased to 12.8% in the IFN-gamma assay. The sensitivity of the IFN-gamma assay compared to CIM was shown to be higher (84.9%) than that of the SICT test (80.2%), but the combination of both tests offered the highest sensitivity (92.9%). The number of false positive reactors (those animals in which CIM was negative) was considerably higher for the IFN-gamma assay than for the SICT test and, conversely, the number of false negative animals (M. bovis isolation but negative immunological result) was higher for the skin test than for the interferon assay. In the herds tested twice, tuberculosis was eradicated after the second cycle of testing in 50%, and in 75% after the third cycle in herds tested three times. The combination of these two techniques instead of separately seems, therefore, to be useful in eradication programmes against bovine tuberculosis.     

Postpartum anestrus in dairy cattle--a review

In modern high-yielding dairy herds fertility is of major economic importance. In order to gain maximum profit, calving intervals should not exceed 365 days. The achievement of a 365-day calving interval requires an early resumption of ovarian activity, an excellent oestrus detection, and a high first-service conception rate. Especially the inability to detect oestrus and to mate the cows by 60 to 80 days after calving is a common problem among dairy farmers nowadays. In this article a review is given about the occurrence, causes, treatment and prevention of post-partum anoestrus in dairy cows.     

Quantification of Mycelium of Botrytis spp. and the Antagonist Ulocladium atrum in Necrotic Leaf Tissue of Cyclamen and Lily by Fluorescence Microscopy and Image Analysis

ABSTRACT A technique was developed to localize and quantify the internal mycelial colonization of necrotic leaf tissue of cyclamen (Cyclamen persicum) or lily (Lilium) by pathogenic Botrytis spp. and the antagonist Ulocladium atrum. This technique allows investigation of competitive substrate colonization by both fungi, which is a key process for biological control of Botrytis spp. by U. atrum. A combination of differential fluorescent labeling and image analysis was applied on cryostat sections of necrotic leaf tissue. Botrytis mycelium was labeled specifically by indirect immunofluorescence using a monoclonal antibody specific for Botrytis spp. And an antimouse fluorescein conjugate. Wheat germ agglutinin conjugated to the fluorochrome TRITC was used to label mycelium of both fungi. Image analysis was used to measure the relative surface area of the cryostat section covered by fluorescing hyphae of Botrytis spp. and by fluorescing hyphae of both fungi. A mathematical conversion was derived and used to calculate the relative mycelial volume of each fungal species in the necrotic tissue based on the measured relative surface areas. Temporal aspects of substrate colonization were studied in a short time series. An analysis of components of variance provided insight into spatial colonization patterns for the fungal species involved and allowed the design of efficient sampling strategies for future experiments.     

Liver pathology and immune response in experimental Fasciola hepatica infections of goats

The relationship between the immune response and the pathogenesis of the disease was studied in different primary and secondary experimental Fasciola hepatica infections of goats. The establishment of the infection, measured as percentage of recovered flukes at the necropsy, was similar in primarily and secondarily infected animals (between 19.7% and 24.3%), but the hepatic damage was much more severe in secondarily infected goats, as revealed by the levels of serum hepatic enzymes GGT and LDH. Primary infection evolves to chronic fasciolosis that did not induce the development of resistance, since goats were highly susceptible to secondary infection, showing severe acute and chronic hepatic lesions that led to the death of some animals in each group. The immune response to the infection was proved by the production of specific IgG antibodies to ESP of F. hepatica and the involvement of CD3+ T lymphocytes and lambda IgG+ plasma cells in the hepatic infiltrate. Secondary infection did not induce any difference in either IgG response or in the cellular composition of the infiltrate of hepatic lesions, although this was much more extended. However, neither antibodies nor cell-mediated response were protective: there was no correlation between IgG levels and fluke burden and there was no evidence of cell-mediated killing of the parasite. This suggests the existence of some immune evasion mechanisms in goat infection with F. hepatica. The parasite may depress the local inflammatory and immune response, as suggested by the scarcity of CD3+ T cells in the infiltrate surrounding acute migratory tunnels. Moreover, in secondary infected goats can be suspected an immunological damage of the liver, since a very severe infiltrate of immune cells replaced wide areas of hepatic parenchyma and an immune-mediated damage of hepatocytes could occur.     

Ketoprofen and phenylbutazone attenuation of PAF-induced lung inflammation in calves

The purposes of this study were: (1) to investigate which arachidonic acid metabolites contributed to platelet-activating factor (PAF) induced pulmonary dysfunction; and (2) to compare the effect of two non-steroidal anti-inflammatory drugs, phenylbutazone and ketoprofen in a model of PAF-induced reversible lung inflammation in six calves. In placebo and phenylbutazone groups, PAF infusion induced significant dysfunctions in the pattern of breathing, mechanics of breathing and gas exchange. These dysfunctions were prevented by ketoprofen pretreatment, except for the mechanics of breathing which was moderately but significantly altered by the PAF challenge. In all calves, leukotriene (LT) B4 plasma concentrations did not significantly increase above baseline values at any time. Prostaglandin (PG) E2 plasma concentrations showed a minor significant increase in phenylbutazone pretreated calves (55.8 +/- 25.8 pg/mL from 36.7 +/- 16.13 pg/mL). Thromboxane (TX) B2 plasma concentration was significantly increased during PAF challenge in placebo- and phenylbutazone-pretreated groups, but not in ketoprofen-pretreated calves (1580.0 +/- 1370 from 42.7 +/- 10.7 pg/mL; 2340 +/- 477 from 63 +/- 32 pg/mL; and 36.5 +/- 4.12 from 39.3 +/- 12.0 pg/mL, respectively). These data suggest that TXA2 is an important cyclooxygenase metabolite of arachidonic acid produced in response to PAF and that ketoprofen (intramuscular injection, 3 mg/kg) is more effective than phenylbutazone (intramuscular injection, 10 mg/kg) in preventing respiratory dysfunctions induced by the PAF challenge 30 min after drug administration. Ketoprofen did not suppress totally the PAF-induced changes in mechanics of breathing, which suggests that PAF or a secondary release of mediators could have a direct action on airway smooth muscle.     

Radiographic measurement of craniocaudal instability in stifle joints of clinically normal dogs and dogs with injury of a cranial cruciate ligament

OBJECTIVE: To determine craniocaudal laxity of the stifle joint of dogs when joints were positioned in tibial compression or neutral position. SAMPLE POPULATION: 19 normal stifle joints in 10 clinically normal dogs, 29 stifle joints with varying injury to the cranial cruciate ligament (10 complete ruptures alone, 10 complete ruptures with concomitant damage to the medial meniscus, 6 partial ruptures alone, and 3 partial ruptures with concomitant meniscal tearing), and 19 unaffected contralateral stifle joints in those 29 dogs. PROCEDURE: Relative displacement of bony landmarks was measured on paired lateral radiographs (neutral and tibial compression positions). Two measuring techniques were customized for use in dogs. RESULTS: The first technique failed to distinguish results in normal stifle joints from those in stifle joints with partial deficiency of cranial cruciate ligaments. Significant differences were found for joints with complete rupture, compared with stifle joints in clinically normal dogs. The second technique detected differences between normal stifle joints and injured joints with partial or complete rupture of the cranial cruciate ligament. Significant differences were not detected between joints with partial versus complete rupture. Adjusting data to account for size of dog did not improve results. CONCLUSIONS AND CLINICAL RELEVANCE: A wide range in measurements of laxity was found for stifle joints with intact cranial cruciate ligaments. Differences in degree of damage to the ligament and medial meniscus cannot be deduced from the amount of relative displacement measured on radiographs. Pathologic changes to the cranial cruciate ligament will not necessarily induce detectable changes in laxity of stifle joints in dogs.     

Clinical and pathologic findings in two draft horses with progressive muscle atrophy, neuromuscular weakness, and abnormal gait characteristic of shivers syndrome

Two Belgian geldings, 4 and 14 years old, respectively, with muscle atrophy, weakness, and abnormal gait characteristic of severe advanced shivers were examined clinically and on necropsy. Neurologic examination revealed no evidence of ataxia, and the clinical diagnosis was neuromuscular weakness and shivers. Necropsies of both horses, including examination of pituitary, brain, spinal cord, spinal roots and ganglia, and peripheral nerves, revealed no gross or histologic abnormalities. Examination of multiple skeletal muscle specimens revealed chronic myopathic changes and periodic acid-Schiff positive, amylase-resistant inclusions within muscle fibers, characteristic of equine polysaccharide storage myopathy. It is suggested that underlying metabolic myopathy may be the cause of muscle weakness and cramping in horses with shivers.