Impact of intramammary tilmicosin infusion as a dry cow therapy

Three hundred subclinically infected quarters of 259 Holstein cows infected with gram‐positive bacteria were selected via quota sampling based on the California Mastitis Test (CMT) result and were divided randomly and equally into treatment and test groups. Quarters of test group (n = 150 in 128 cows) were treated with an intramammary infusion of tilmicosin, and quarters of the control group (n = 150 in 131 cows) were treated with cloxacillin as a traditional intramammary infusion of dry cow (DC) ointment. Cows with more than one infected quarter were randomly assigned to the same group, and adjacent quarters were treated the same. The milk samples of all quarters were obtained, and bacterial cultures and somatic cell count (SCC) were tested before dry cow therapy (DCT) (50 ± 15 days before parturition), and finally on day 2 of the next lactation. Results have shown that total bacteriological cure rates on day 2 of the next lactation were 45% and 78%, (p = .01), new infection rates were 43.3% and 56.6%, and SCC was (6.732 × 10⁵ ± 3.124 × 10⁵) and (5.025 × 10⁵ ± 2.935 × 10⁵), (p > .05) in test and control groups, respectively. Tilmicosin had less effect on reducing IMI due to Corynebacterium bovis, and had no effect on Streptococcus agalactiae, but had a potent effect against Staphylococcus aureus. It was concluded that tilmicosin alone should not be infused as an alternative to conventional dry cow therapy. However, it had a significant effect against S. aureus, and the potential of tilmicosin to treat S. aureus IMI should be confirmed in further studies.     

生物降解型吡喹酮微囊的构建及其药剂学性质的研究

以生物可降解的明胶和阿拉伯胶为囊材 ,采用复凝聚法制得适合肌肉注射的吡喹酮微囊 ;考察其形态学特征及吡喹酮微囊的体外动态与静态释药情况。建立高效液相紫外色谱测定微囊内药物含量。结果 3批生物降解型吡喹酮微囊显微镜下和电镜下外观均一、光滑 ,平均载药量为 10 .0 3%,平均包封率为 6 1.75 %,平均粒径为45 .1μm;体外释药研究结果表明微囊内的药物无突释现象。该生物降解型吡喹酮微囊可达到缓慢释放和长效制剂的基本要求。     

The hydrogen peroxide, as a potentially useful slurry disinfectant

Hydrogen peroxide is used more and more as the water and wastewater as well as slurry disinfectant. Its advantages over other oxidants are nontoxic, harmless, and environmentally acceptable by products. The basic task in the disinfection of slurry is to destroy or remove infectious microorganisms so that the slurry cannot transmit disease producing agents, when disposed on the land or into waters.

In the present study the effect of hydrogen peroxide disinfectant with catalytic action of metal ions, silver and ferrous, was investigated in the hygienization process of pig and cattle slurry.

In order to determine the optimal concentration of disinfectant, the effect of a range of final concentrations of hydrogen peroxide alone and with metal ions was investigated. Organoleptic, physicochemical and bacteriologic parameters were analyzed for wastewater quality assessment in accordance with standard methods.

The results illustrated an improvement of organoleptic properties: color and odor, the oxidation of organic matter across reduction of BOD₅ and ammonium content of the treated slurries as well as a decrease of aerobic mesophilic bacteria and total coliform bacteria numbers.

This investigation indicated that the disinfection of slurry with the oxidative compounds with hydrogen peroxide basis and catalytic action of silver and ferrous ions can be recommended for its bactericidal and oxidative effect.     

Combination of quaternary ammonia and glutaraldehyde as a disinfectant against enveloped and non-enveloped viruses

Infectious bursal disease is a highly infectious immunosuppressive disease of chickens endemic in many poultry-producing areas around the world. The non-enveloped virus that causes the disease, infectious bursal disease virus (IBDV), is highly stable and resistant to inactivation by common disinfectants. Avian influenza viruses (AIV), on the other hand, are highly vulnerable to most disinfectants due to their phospholipid envelope, but still pose a major threat to the poultry industry, as the outbreaks in 2015 in the United States have shown. Several studies have evaluated the efficacy of disinfectants against both IBDV and AIV but failed to take into consideration factors that would affect the disinfectant efficacy once used in the field, such as organic material. Therefore, the aim of this study was to investigate the efficacy of a commercial combination of quaternary ammonia and glutaraldehyde as a disinfectant against IBDV and AIV in the presence of organic material commonly found in the commercial poultry industry: fecal matter alone, feathers/dust mixed with feces, and bedding material mixed with feces. After a 10-minute disinfectant contact time, each surface was swabbed and virus isolation attempted in embryonated specific-pathogen-free (SPF) chicken eggs. The non-enveloped very virulent (vv) IBDV was reisolated from spiked feces and shavings treated with the disinfectant. This was confirmed by RT-PCR detection of the virus. In contrast, no viral isolate or RT-PCR product was obtained from the samples collected from spiked feathers/dust treated with the disinfectant. Finally, no low pathogenic (LP) AI was re-isolated from the samples treated with the disinfectant indicating that, under laboratory conditions, the combination of quaternary ammonia and glutaraldehyde was partially and completely effective in the inactivation of vvIBDV and LPAI, respectively. Not only the viral envelope, but also the presence of organic matter plays an important role in the viral resistance to disinfectants.     

Production and functional characterization of recombinant bovine interleukin-8 as a specific neutrophil activator and chemoattractant

Interleukin-8, a member of the chemokine family of cytokines, is a potent neutrophil chemoattractant in many non-rodent species. In this study, recombinant bovine interleukin-8 (rbIL-8) was expressed in bacteria as a glutathione-S-transferase fusion protein. The fusion protein was purified by glutathione-Sepharose affinity chromatography and recombinant rbIL-8 was eluted by cleaving with thrombin. The purified rbIL-8 molecule was approximately 8 kDa and was confirmed as authentic IL-8 by Western analysis. Recombinant bovine IL-8 induced specific dose-dependent in vitro chemotaxis of neutrophils at doses as low as 1.0 ng/ml, and this activity was inhibited by pre-treatment of rbIL-8 with a monoclonal antibody to ovine IL-8. Neutrophils exposed to rbIL-8 developed pseudopodia and became elongated as determined by microscopic analysis and flow cytometry. Injection of 3.3 ng to 3.3 microg of rbIL-8 into the skin of a normal calf induced dose-dependent recruitment of neutrophils but not eosinophils. Intravascular margination of neutrophils was obvious at the injection sites from 15 to 60 min after administration of rbIL-8, and extravascular neutrophil numbers increased steadily from 1 to 18 h after injection. Neutrophils with morphologic features of apoptosis were detected in these lesions at 18 and 30 h after injection, and this correlated with reduction in the number of dermal neutrophils. These results confirm unequivocally that bovine IL-8 functions as a neutrophil, but not an eosinophil, chemoattractant in vitro and in vivo.     

Patterns of nonclinical intramammary infection in a ewe flock

Coagulase-negative staphylococci were the most frequent bacterial isolates from nonclinical intramammary infections (NIMI) in a ewe flock. The prevalence of NIMI was 22.9% of the udder halves at lambing and decreased to 12.5% or less between week 2 and week 6 of lactation. The decrease was due mainly to the elimination of infections involving coagulase-negative staphylococci. The frequency of new NIMI in the first 6 weeks of lactation was less than 1% of the noninfected udder halves per week. The prevalence of NIMI increased steadily from 16.1% of the udder halves at the time of weaning the lambs to 29% at postweaning week 3. The new infection rate averaged 9.7% per week during the postweaning 3 weeks. The principal bacterial isolate in the new NIMI was coagulase-negative staphylococcus. Nonclinical intramammary infection in a ewe flock was monitored by bacteriologic cultural examinations of milk samples obtained from both udder halves of 24 ewes during early lactation and of 31 ewes in the same flock during the early postweaning period. The patterns of NIMI were similar to the patterns reported in cattle.     

Evaluation of the efficacy of disinfectant footbaths as used in veterinary hospitals

OBJECTIVE: To evaluate efficacy of 2 disinfectants as used in footbaths in veterinary hospitals for reducing bacterial contamination of footwear. DESIGN: Prospective study. SAMPLE POPULATION: Bacteria collected from the soles of rubber boots after experimental contamination and exposure to disinfectant solutions or control conditions. PROCEDURES: Investigators contaminated boots by walking through soiled straw animal bedding. Swab samples were collected from the sole of 1 boot (right or left) without treatment. The other boot was briefly immersed in a disinfectant solution (either a quaternary ammonium compound [QAC] or a peroxygen compound) or water, and samples were collected after 7 minutes. Differences associated with the experimental treatments were analyzed statistically. Veterinary teaching hospitals (VTHs) in the United States and Canada were contacted to obtain information about the use of footbaths. RESULTS: Mean bacterial concentrations from peroxygen-treated boots were 67% to 78% lower, compared with samples taken from untreated boots. In contrast, there were no statistically detectable differences in mean bacterial concentrations in samples taken from QAC- or water-treated boots, compared with control boots. Disinfectant footbaths were reportedly used in 30 of 31 VTHs. CONCLUSIONS AND CLINICAL RELEVANCE: Disinfectant solution containing peroxygen applied in a footbath reduced bacterial concentrations on rubber boots under conditions representative of those found in VTHs. Footbaths are commonly used as a method to control infectious diseases in veterinary hospitals. Disinfectant footbaths should not be expected to sterilize footwear, but they may help in reducing the risk for nosocomial infection when used with effective disinfectants.     

Production and characterization of recombinant equine prorelaxin

Relaxin is a peptide hormone produced by a wide variety of mammals. In the horse, the placenta is the major source of relaxin. Since pure equine relaxin is difficult to obtain to study its role in the pregnant mare, the objectives of this study were to produce recombinant equine prorelaxin and characterize its immunological and biological activity. First, an equine relaxin gene cassette was transfected into immortalized bovine mammary epithelial (MAC-T) cells. Second, immunological activity of media conditioned by transfected MAC-T cells was tested by Western blotting and quantified using a homologous equine radioimmunoassay. Finally, bioactivity of the conditioned media was tested using the human monocyte cell line, THP-1, which exhibits a rapid and dose-dependent increase in the accumulation of cAMP upon binding relaxin. The results showed that conditioned media, concentrated 5x, yielded 4.11 +/- 0.81 ng/ml recombinant equine prorelaxin. In addition, a 19 kDa immunoreactive band, corresponding to the expected size of equine prorelaxin, was visualized by SDS-PAGE. THP-1 cells incubated with conditioned media (5x) from transfected cells, in the presence of forskolin (1 microM) and isobutylmethylxanthine (50 microM), showed an increase in cAMP production over media from mock-transfected cells alone. In conclusion, recombinant equine prorelaxin secreted by MAC-T cells was both immunologically and biologically active. This study demonstrates the first attempt to produce recombinant equine prorelaxin, important for further study of the role of relaxin in the mare.     

常用消毒剂种类及应用

消毒是为了防制传染病的传播和再发生,清除家禽在饲养过程中产生的饲养环境微生物的污染,维持家禽的正常生产,合理地选择消毒剂在养鸡上是重要的一环。１常用消毒剂种类１．１含氯类消毒剂主要有漂白粉、抗毒威、除菌净等,它是靠消毒过程中释放有效氯起作用,但对病毒作用不大,性质不稳定,容易受日光照射和水质及ｐＨ值影响,有效度易散失,故必须现配现用。１．２过氧化物类消毒剂主要有过氧乙酸,此类消毒剂具有强大氧化能力,易溶于水,在消毒过程中有效成分为醋酸,其对细菌、霉菌和芽孢有杀灭作用,由于它的化学性质不稳定,现多用Ａ、Ｂ液分装,…     

Use of a topical disinfectant as part of a hoof care programme for horses with diseases of the hoof capsule

Twenty-three horses with persistent hoof horn defects were treated topically with a hoof disinfectant as part of a hoof care programme for a year. The active ingredients of the disinfectant were a poloaximer-iodine complex, ethylenediamine dihydriodide, isopropyl alcohol and propylene glycol. Hoof trimmings were taken at the start of the study and every six weeks, and examined by scanning and transmission electron microscopy. At the beginning of the study all the horn samples contained large numbers of bacteria, and samples from eight of the horses also had fungal hyphae intermingled with the bacteria. After the application of the hoof disinfectant and adjustments to their diet, there were rapid improvements in the gross appearance of the feet of all the horses; some of them improved within two to three weeks and by 12 weeks the horn quality of all the horses had greatly improved.     

Direct and indirect measurement of somatic cell count as indicator of intramammary infection in dairy goats

Background

Mastitis is the most important and costly disease in dairy goat production. Subclinical mastitis is common in goats and is mainly caused by contagious bacteria. Several methods to diagnose subclinical mastitis are available. In this study indirect measurement of somatic cell count (SCC) by California Mastitis Test (CMT) and direct measurement of SCC using a portable deLaval cell counter (DCC) are evaluated. Swedish goat farmers would primarily benefit from diagnostic methods that can be used at the farm. The purpose of the study was to evaluate SCC measured by CMT and DCC as possible markers for intramammary infection (IMI) in goats without clinical symptoms of mastitis. Moreover to see how well indirect measurement of SCC (CMT) corresponded to direct measurement of SCC (DCC).

Method

Udder half milk samples were collected once from dairy goats (n = 111), in five different farms in Northern and Central Sweden. Only clinically healthy animals were included in the study. All goats were in mid to late lactation at sampling. Milk samples were analyzed for SCC by CMT and DCC at the farm, and for bacterial growth at the laboratory.

Results

Intramammary infection, defined as growth of udder pathogens, was found in 39 (18%) of the milk samples. No growth was found in 180 (81%) samples while 3 (1%) samples were contaminated. The most frequently isolated bacterial species was coagulase negative staphylococci (CNS) (72% of all isolates), followed by Staphylococcus aureus (23% of all isolates). Somatic cell count measured by DCC was strongly (p = 0.000) associated with bacterial growth. There was also a very strong association between CMT and bacterial growth. CMT 1 was associated with freedom of IMI while CMT ≥2 was associated with IMI. Indirect measurement of SCC by CMT was well correlated with SCC measured by DCC.

Conclusions

According to the results, SCC measured with CMT or DCC can predict udder infection in goats, and CMT can be used as a predictor of the SCC.     

Epidemiology of Streptococcus uberis intramammary infections in a dairy herd.

From 1987 to 1991, almost 36,000 quarter samples of mammary secretion representing 1790 lactations of 510 dairy cows from a research herd were collected for bacteriological examination. The percentage of cows infected with Streptococcus uberis ranged from 12 to 16% of cows/year. S. uberis was isolated from 14.2% of lactations over the 5-year period. The prevalence of S. uberis intramammary infection (IMI) was significantly higher in cows with > or = 4 lactations than in cows with 3 or fewer lactations. Regardless of lactation number, the prevalence of S. uberis was highest before parturition, during early lactation and near drying off. The prevalence of S. uberis infected quarters ranged from 1.3 to 2.3% of quarters/year; the prevalence rate for the 5-year period was 2% of quarters. The quarter prevalence of S. uberis was lowest in cows with < or = 3 lactations, increased significantly with lactation number and was highest in cows with > or = 6 lactations. The percentage of quarters infected with S. uberis varied significantly by year. The majority (95%) of S. uberis IMI were subclinical. The ratio of subclinical IMI to clinical IMI was lowest during early lactation, and increased with days in milk, and with lactation age except for cows in their 5th and 6th lactations. Results of this epidemiological investigation suggest that opportunities exist where suitable control measures could be applied to reduce the impact of S. uberis infections in the dairy herd.     

Effect on outcome of intramammary challenge exposure with Staphylococcus aureus of somatic cell concentration and presence of an intramammary device

Results of experimental Staphylococcus aureus intramammary challenge of all quarters of 6 cows, each fitted with an intramammary device (IMD) in 2 quarters, and of 10 quarters of 3 cows not fitted with an IMD were reported. Infection was established in all 34 quarters, regardless of presence or absence of an IMD. Neither the course nor severity of early S aureus intramammary infection were influenced by the presence of an IMD or by differences in milk somatic cell (MSC) concentration in the gland at the time of bacterial challenge infusion, up to a MSC concentration of nearly 1 million/ml. Cumulative success of experimental infection in this and a previous study from our laboratory was nearly 100% in glands in which the MSC concentration was less than 1 million/ml and about 17% when the MSC concentration exceeded 1 million/ml.     

The effect of intramuscular and intramammary vaccination of cows on antibody levels and resistance to intramammary infection by Staphylococcus aureus.

Cows were vaccinated simultaneously by the intramuscular and intramammary route with formolised Staphylococcus aureus cells of strains BB, Mexi and 3528. Vaccination resulted in slight increases in serum agglutinin titres, but the levels of the agglutinins in milk and colostrum were not higher in vaccinated cows than in the unvaccinated controls. Vaccination did not result in higher levels of IgM, IgG1, IgG2 or IgA immunoglobulins in serum, colostrum or milk as compared with controls. Vaccinated cows, particularly those in which strain 3528 was used, showed some resistance to infection following challenge with low numbers of viable S aureus Mexi, but there was no resistance to infection when similar numbers of the virulent BB strain were used for challenge. It is concluded that vaccination is unlikely to prevent infection of the bovine udder by S aureus.     

癸甲溴铵戊二醛消毒剂杀菌效果的试验

为了防止畜禽疫病不断发生,消毒工作是预防和控制的重要环节之一,是切断病原微生物传播的重要手段。随着人们对消毒重要性认识的逐步提高,实际工作中消毒药物的使用越来越广泛。而消毒效果与选用的消毒剂有很大的关系。近年来,国内外均致力于寻求高效、快速、广谱的消毒剂。其消毒效果往往受到微生物的种类、pH、温度、浓度、有机物等因素的影响。为了解癸甲溴铵戊二醛的消毒效果,选用了金黄色葡萄球菌、大肠埃希氏杆菌、溶血性链球菌C群进行定性杀灭试验、载体定量杀菌试验和现场消毒效果的观察,为评价该消毒剂对细菌杀灭效果提供依据。1…     

Antibiotic persistence and tolerance in the lactating sheep following a course of intramammary therapy

The commercial use of sheep for the production of milk and milk products is attractive to farmers actively diversifying their dairy interests due to the impact of the quota system. As intensification of milking increases, flock sizes will enlarge and the incidence of ovine mastitis will inevitably increase. The pharmaceutical industry and the veterinary practitioner will be required to provide advice and data upon the performance of currently available bovine intramammary preparations for the sheep. This study produces evidence to confirm that one available bovine intramammary preparation, when infused into milking sheep, produced a withholding time approximately three times as long as that defined for the cow. Following a course of three infusions over a period of 24 hours after consecutive milkings, milk was not acceptable for human consumption or for the production of cheese and yoghurts until 136 hours following the final infusion. This situation is likely to be representative of that which will occur with other intramammary products used in the ovine species following infusion with bovine intramammary preparations.     

Pharmacokinetics and milk discard times of pirlimycin after intramammary infusion: a population approach

A population pharmacokinetic approach was used to analyse milk concentration data to determine whether milk discard times and the clearance of intramammary infusions of pirlimycin could be adequately predicted by readily available demographic variables. Milk samples were collected at 12 hourly milking intervals after dosing with pirlimycin during product development from both normal cows (primary data) and cows with naturally occurring mastitis (validation data) and pirlimycin concentration was determined by microbial inhibition assay. The data were analysed by the conditional estimation/ maximum likelihood population approach within the computer program PPharm and fitted a two compartment open model. Bayesian estimates of individual parameters allowed solutions for each cow, predicting the time after last dosing by which milk concentration reached the target safe concentration. From this population of times, the 95% confidence interval of the 99th percentile was defined as the milk discard time. After elimination of one very low producing outlier, the calculated discard time agreed with the label recommendation of 36 h (3 milkings, USA) after the last dose. Milk pirlimycin clearance was strongly and positively correlated to the logarithm of the kilograms of milk produced in 24 h at time of dosing (r2=0.939). Agreement was strong at most time points between predicted and measured pirlimycin concentrations in milk from cows with mastitis. This alternative method for determining milk discard times was compared to existing recommendations.     

Production and characterization of monoclonal antibodies to Ehrlichia risticii

Hybridomas producing monoclonal antibodies to Ehrlichia risticii were developed to provide a means of molecular investigation of the biochemical and immunopathologic characteristics of the organism. All of 6 stable monoclonal antibodies obtained were IgG isotypes. The ascitic fluid titers induced by the hybridomas ranged from 10(2) to 10(7). Competitive binding experiments conducted by ELISA and binding of labeled protein A to antigen-antibody complexes indicated competition among monoclonal antibodies. Two monoclonal antibodies (HybI and 14D4) were reactive in an indirect fluorescent antibody test; these antibodies also bound a maximum of labeled protein A, indicating recognition of epitopes on the surface of the ehrlichia. Protein specificity of monoclonal antibodies could not be demonstrated with western blot procedure. HybI monoclonal antibody, however, did precipitate the 28 kD protein from 125I-surface-labeled ehrlichiae and was shown to be specific to E risticii on the basis of nonreactivity with E sennetsu, using the indirect fluorescent antibody test. By use of the different monoclonal antibodies as probes, more definitive molecular studies now will be feasible.     

Prevalence and effects of intramammary infection in beef cows

Prevalence and effects of intramammary infection in 322 beef cows was determined during three calving intervals. Intramammary infection was confirmed in 37% of cows and 18.1% of quarters. Coagulase-positive staphylococci accounted for 17.9% of infections with Staphylococcus aureus isolated from 7.1% of cows. Coagulase-negative staphylococci and micrococci accounted for the remainder of infectious organisms. Butterfat and total protein levels were reduced 27.3 (P less than .05) and 25.5% (P less than .01), respectively, in milk from quarters infected with S. aureus. Somatic cell counts were elevated (P less than .001) with 3,827 X 10(3) cells/ml for S. aureus-infected quarters as compared with 555 X 10(3) cells/ml for uninfected quarters. Somatic cell counts were negatively correlated with 210-d calf weaning weights. Staphylococcus aureus-infected cows weaned calves weighing 19.1 kg less (P less than .01) than uninfected cows. At a present market value of $1.65/kg, economic losses were placed at $31.43/calf from cows infected with S. aureus in one or more quarters.