水分对硝酸磷肥中氮的扩散及其肥效的影响

国产硝酸磷肥含氮27%,磷13.5%。所含速效氮中硝态氮均占一半。研究麦田不同水分对硝酸磷肥中硝态氮在土壤中扩散结果显示,硝态氮在土壤中下移深度与土壤湿润峰的深度基本一致,在小麦越冬期有表聚现象。当灌水量为田间持水量时,硝态氮移动深度为40～50cm,是在主要根系活动层内,这对小麦吸收有利,不会产生氮的流失。等氮磷条件下,硝酸磷肥与磷铵加尿素在北方地区有同样肥效。     

Type-I hypersensitivity as a component of eosinophilic myositis (muscular sarcocystosis) in cattle

Eight bovine hearts with lesions of eosinophilic myositis (EM) and 2 bovine hearts without EM lesions were collected at slaughter. Blood samples from these 10 hearts, and the heart of a newborn calf also were collected. Histologically, Sarcocystis cruzi was identified in the 8 hearts with EM lesions and the 2 hearts without EM lesions, but not in the heart of the newborn calf. Serum was harvested from the 10 blood samples and was used in homologous, modified, passive cutaneous anaphylaxis tests. Antigen was prepared from S cruzi bradyzoites isolated from the 2 hearts without EM lesions. Serum samples from the 8 cattle with EM lesions reacted positively to S cruzi antigen. When heat-inactivated IgE in serum (56 C for 4 hours) was used, all passive cutaneous anaphylaxis responses were considered negative. Using ELISA, serum IgE concentrations from the 10 cattle with and without EM lesions were 2.2 to 9 U/ml. As determined by radial immunodiffusion, IgM concentrations were 80 to 215 mg/dl. Immunoglobulin G concentrations were 420 to 2,050 mg/dl, but most were less than or equal to 1,700 mg/dl. Immunoglobulin A concentrations were 0 to 62 mg/dl; 1 steer with EM lesions had 0 mg/dl. Double-gel immunodiffusion confirmed the presence of Sarcocystis-specific precipitating antibodies. Sera from the 10 cattle with and without EM lesions formed at least 1 precipitin band.     

Occurrence of halo spot in barley caused by Pseudoseptoria donacis in Argentina

Barley is an important malting crop extensively cultivated in the province of Buenos Aires (AR). In 1992, an unusual disease was detected with a prevalence of 8% on 36 commercial fields examined in this province. The pattern of the disease, the characteristics of the pathogen and the test for pathogenicity indicated that the causal agent was Pseudoseptoria donacis.     

Effects of abiotic variables on the response of carnation cultivars to Fusarium oxysporum f.sp. dianthi

The effects of abiotic variables on the response of carnation cultivars to Fusarium oxysporum f.sp. dianthi ( F.o. dianthi  ) were examined in experiments conducted under semi-controlled environments. The abiotic variables examined were solar radiation intensity, temperature and growth substrate. Temperature was not controlled, but differed markedly among experiments, thus, its effect was not determined quantitatively. Disease incidence and disease severity varied significantly among the experiments (due mainly to differences in temperature), among the solar radiation treatments and among the cultivars tested. The three-way interaction term (i.e. cultivar × shade treatment × experiment) was highly significant ( P  < 0.001) when both disease incidence and disease severity were considered, indicating that no single variable was predominant in determining disease intensity. The effects of the growth substrate on disease progress was examined in plants grown in tuff or in tuff mixed with peat (1 : 1 and 1 : 3) substrates. The growth substrate had a potent effect on disease development in the less susceptible cultivars. Severe epidemics developed in all cultivars when they were grown in the tuff/peat mixture, although some were resistant when grown in tuff alone. These results led to the conclusion that the carnation response to F.o. dianthi is substantially influenced by the environmental conditions of the test.     

Bovine Leukocyte Adhesion Deficiency in Danish Holstein-Friesian Cattle: I. PCR Screening and Allele Frequency Estimation

Jergensen, C. B., J. S. Agerholm, J. Pedersen and P. D. Thomsen: Bovine leukocyte adhesion deficiency in Danish Holstein-Friesian Cattle I. PCR screening and allele frequency estimation. Acta vet. Scand. 1993,34,231-236.–A screening program for bovine leukocyte adhesion deficiency (BLAD) in Danish Holstein-Friesian cattle has been initiated. During the first months 1611 animals were tested by a PCR based assay. Of these animals 1256, 346, and 8 were assigned normal, BLAD carriers, and BLAD affected animals, respectively One bull, born as a co-twin, showed weak reaction for the BLAD allele on DNA isolated from leukocytes, but a normal genotype on DNA isolated from semen. Chromosome analysis showed that this bull was a blood chimaera. Estimation of the BLAD allele frequency upon the PCR test results showed that around 450 Danish calves born in 1991 might have been affected with the recessive disorder.     

Multiresidue assay for benzimidazole anthelmintics by liquid chromatography and confirmation by gas chromatography/selected-ion monitoring electron impact mass spectrometry

A multiresidue method utilizing all-disposable labware has been developed for 8 benzimidazole anthelmintics from ovine, bovine, and swine muscle and liver tissues. After an initial extraction with ethyl acetate and subsequent evaporation, a 3-component extraction using hexane, ethanol, and 0.2N HCl was used for final cleanup. Clean extracts were produced for separation and determination by reverse-phase liquid chromatography at 298 nm, using methanol and aqueous buffer as mobile phase. A synthesized internal standard, 2-(n-butylmercapto)benzimidazole, was used for quantitation of all drugs. Results are included along with statistical information verifying the performance of the method. Spiked control tissues and incurred drug tissues were used for an intralaboratory study with a concentration range of 50-1470 ppb. A series of standard curves at 0, 50, 100, and 200 ppb were analyzed. Overall recovery at the 100 ppb level averaged 92% (CV 8%) in liver tissues, across all 3 species and 88% (CV 5%) in muscle tissues across all 3 species. Results were confirmed by gas chromatography/mass spectrometry with acid hydrolysis of the remaining extract in 2N HCl followed by re-extraction of the amine and derivatization to the tert-butyldimethylsilyl derivative. The anthelmintics were identified by gas chromatography/selected ion monitoring electron-impact mass spectrometry. Ion ratio measurements were taken and compared to standard material. CVs averaged 10% or less for all drugs tested.     

The effects of stubble burning and tillage on soil carbon sequestration and crop productivity in southeastern Australia

Abstract. In Australia, stubble burning and tillage are two of the major processes responsible for the decline of soil organic carbon concentration in cropped soils, and the resulting soil degradation. However, the relative importance of these two practices in influencing the soil organic carbon concentration and the long-term impact on soil quality and productivity are not clear. The effects of stubble burning as practised by farmers in southeastern Australia were evaluated in two field trials, one of 19 years duration, the other of 5 years. Conventional tillage (three tillage passes) led to greater loss of soil organic carbon than stubble burning. Loss of total soil organic carbon attributed to stubble burning in the 0–10 cm layer was estimated to be 1.75 t C ha⁻¹ over the period of the 19-year trial, equivalent to 29% of that lost due to tillage. In the 5-year trial, no change in soil organic carbon due to stubble burning was detectable. Changes in soil quality associated with stubble burning detected in the longer trial included a reduction in macro-aggregate stability, and increases in pH and exchangeable K⁺. Only the latter two were detected in the shorter trial. A higher mean wheat yield (average 0.15 t ha⁻¹) following stubble burning was observed in the 19-year trial but not in the 5-year trial. Research to monitor the longer term effects of stubble burning is needed, and to identify conditions where loss of soil organic carbon is minimized.     

Enzootic abortion in a goat herd, caused by mixed infection with Coxiella burnetii and Chlamydia psittaci. Case report]

We report on an outbreak of enzootic abortion in a herd of goats with high losses caused by mixed infection with Coxiella burnetii and Chlamydia psittaci. Both agents could be detected by microscopic investigation of smears from afterbirths by Giménez staining and by a capture enzyme-linked immunofluorescence assay (Capture ELIFA). Additionally, Coxiella burnetii was isolated from the same tissues in BGM cell cultures. Serological investigations with CF, indirect ELIFA, and IF tests revealed high antibody titers against both agents in most animals. Coxiella antigen was still detected 91 days later in milk samples of two infected goats by Capture ELIFA.     

In vitro activity of danofloxacin, tylosin and oxytetracycline against mycoplasmas of veterinary importance

The activities of danofloxacin, a novel fluoroquinolone, and two other antimicrobials were determined in vitro against field isolates of seven Mycoplasma species of veterinary importance isolated from cattle, swine and poultry in five European countries. The minimum inhibitory concentrations (MIC) of danofloxacin, tylosin and oxytetracycline were determined against a total of 68 isolates. Danofloxacin showed excellent activity against isolates of all Mycoplasma species (range 0·008 to 0·5 μg ml⁻¹), but in some isolates there was evidence of reduced sensitivity to tylosin (range 0·008 to 2·0 μg ml⁻¹) and oxytetracycline (range 0·008 to over 16·0 μg ml⁻¹). Danofloxacin was more active than other antimicrobials against, M hyopneumoniae, M dispar and M bovigenitalium, and showed activity similar to that of tylosin against M bovis and M gallisepticum. Tylosin was the most active against M synoviae and M hyosynoviae. Generally, oxytetracycline showed the poorest activity, but was superior to tylosin against M bovigenitalium. A second (final) MIC reading was taken for all isolates 14 or 21 days after the initial reading, and MIC values rose during that time. However, the increase seen in danofloxacin values (typically one to two dilutions) was less than that seen for tylosin and oxytetracycline. It is concluded that danofloxacin is highly active in vitro against all of the Mycoplasma species tested, and thus shows great potential for the treatment of respiratory and other infections caused by Mycoplasma species in cattle, pigs and poultry.     

Aerosol therapy in the equine species

Inhalation therapy plays an increasing role in the management of equine respiratory disorders. Thisalternative to systematic treatment permits a high concentration of medication to act locally while minimizing side effects and residues. In human medicine, literature in this field is prolific and continuously renewed, whereas in veterinary medicine, applications of aerosol therapy are less extensive. This review considers the principles of action of the different types of devices used for inhalation, i.e., nebulization, metered-dose inhalation and dry powder inhalation, describes the technical and practical requirements for their use in the equine species and considers the advantages and disadvantages of each inhalation device. The pharmacological agents currently administered to horses by inhalation are also discussed. Perspectives of aerosol therapy in the equine species, including aerosols already used in human medicine and their potential applications for horses are described.