Effect of pre‐milking teat disinfection on clinical mastitis incidence in a dairy herd in Northern Queensland,Australia          下载免费PDF全文

SM Rowe  WP Tranter  RA Laven 《Australian veterinary journal》2018,96(3):69-75

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A comparison of the effect of short-acting and long-acting cloxacillin-based dry-cow therapy on somatic cell counts after calving in cows also given internal teat sealants     

LK Whitfield  RA Laven 《New Zealand veterinary journal》2018,66(1):44-47

AIM: To compare, in cows treated with an internal teat sealant, the effect of short-acting and long-acting cloxacillin-based dry-cow therapy on somatic cell counts (SCC) after calving.

METHODS: Cows from a spring-calving, pasture-based dairy farm in the Manawatu-Whanganui region of New Zealand were randomly allocated to receive either a short-acting cloxacillin and ampicillin dry-cow therapy and internal teat sealant (n=291) or a long-acting cloxacillin and ampicillin dry-cow therapy and internal teat sealant (n=288) at the end of lactation. Cows were managed on-farm with routine husbandry procedures through the dry period and following calving. A multivariable logistic regression model was used to determine the association between length of action of dry-cow therapy and the proportion of cows with a SCC >150,000?cells/mL at the first herd test after calving.

RESULTS: Age of cow, mean SCC for the preceding season and interval from calving to the first post-calving herd test were all associated with the proportion of cows with an individual SCC >150,000?cells/mL at the first herd test (p<0.001) Treatment with the short-acting dry-cow therapy was not associated with decreased odds of cows having a SCC >150,000?cells/mL at the first herd test compared with treatment with long-acting dry-cow therapy (OR=0.724; 95% CI=0.40–1.30).

CONCLUSIONS AND CLINICAL RELEVANCE: In this herd, which routinely used internal teat sealants, the use of short-acting cloxacillin-based dry-cow therapy did not result in an increased proportion of cows with elevated SSC post-calving. This was a single farm, single year study but indicates that in this herd, changing from a long-acting to a short-acting antimicrobial may have no impact on the prevalence of subclinical mastitis.  相似文献   

Canine demodicosis: a retrospective study of a veterinary hospital population in California,USA (2000–2016)          下载免费PDF全文

Daniel G Bowden  Catherine A. Outerbridge  Marguerite B. Kissel  Jerome N. Baron  Stephen D. White 《Veterinary dermatology》2018,29(1):19-e10

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Sexual Recombination in Gibberella zeae     

Bowden RL  Leslie JF 《Phytopathology》1999,89(2):182-188

ABSTRACT We developed a method for inducing sexual outcrosses in the homothallic Ascomycete fungus Gibberella zeae (anamorph: Fusarium graminearum). Strains were marked with different nitrate nonutilizing (nit) mutations, and vegetative compatibility groups served as additional markers in some crosses. Strains with complementary nit mutations were cocultured on carrot agar plates. Ascospores from individual perithecia were plated on a minimal medium (MM) containing nitrate as the sole nitrogen source. Crosses between different nit mutants segregated in expected ratios (3:1 nit(-):nit(+)) from heterozygous perithecia. Analysis of vegetative compatibility groups of progeny of two crosses indicated two and three vegetative incompatibility (vic) genes segregating, respectively. For rapid testing of sexual recombination between nit mutants, perithecia were inverted over MM to deposit actively discharged ascospores. Development of proto-trophic wild-type colonies was taken as evidence of sexual recombination. Strains of G. zeae group 2 from Japan, Nepal, and South Africa, and from Indiana, Kansas, and Ohio in the United States were sexually interfertile. Four group 1 strains were not interfertile among themselves or with seven group 2 strains. Attempts to cross G. zeae with representatives of F. acuminatum, F. avenaceum, F. culmorum, F. crookwellense, F. oxysporum, and three mating populations of G. fujikuroi were not successful.  相似文献   

Observations on surgically induced insufficiency of the canine mitral valve     

W E Bousfield  N L Bowden 《The British veterinary journal》1972,128(11):567-577

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Diversity of Epidemic Populations of Gibberella zeae from Small Quadrats in Kansas and North Dakota     

Zeller KA  Bowden RL  Leslie JF 《Phytopathology》2003,93(7):874-880

ABSTRACT Gibberella zeae (anamorph Fusarium graminearum) causes Fusarium head blight (FHB) of wheat and barley and has been responsible for several billion dollars of losses in the United States since the early 1990s. We isolated G. zeae from the top, middle, and bottom positions of wheat spikes collected from 0.25-m(2) quadrats during severe FHB epidemics in a single Kansas (KS) field (1993) and in a single North Dakota (ND) field (1994). Three amplified fragment length polymorphism (AFLP) primer pairs were used to resolve 94 polymorphic loci from 253 isolates. Members of a subset of 26 isolates also were tested for vegetative compatibility groups (VCGs). Both methods indicated high levels of genotypic variability and identified the same sets of isolates as probable clones. The mean number of AFLP multilocus haplotypes per head was approximately 1.8 in each population, but this value probably underestimates the true mean due to the small number of samples taken from each head. Isolates with the same AFLP haplotype often were recovered from different positions in a single head, but only rarely were such apparently clonal isolates recovered from more than one head within a quadrat, a pattern that is consistent with a genetically diverse initial inoculum and limited secondary spread. The KS and ND samples had no common AFLP haplotypes. All G. zeae isolates had high AFLP fingerprint similarity (>70%, unweighted pair group method with arithmetic means similarity) to reference isolates of G. zeae lineage 7. The genetic identity between the KS and ND populations was >99% and the estimated effective migration rate was high (Nm approximately 70). Tests for linkage disequilibrium provide little evidence for nonrandom associations between loci. Our results suggest that these populations are parts of a single, panmictic population that experiences frequent recombination. Our results also suggest that a variety of population sampling designs may be satisfactory for assessing diversity in this fungus.  相似文献   

An Allee Effect Reduces the Invasive Potential of Tilletia indica     

Garrett KA  Bowden RL 《Phytopathology》2002,92(11):1152-1159

ABSTRACT The Karnal bunt pathogen, Tilletia indica, is heterothallic and depends on encounters on wheat spikes between airborne secondary sporidia of different mating types for successful infection and reproduction. This life history characteristic results in reduced reproductive success for lower population densities. Such destabilizing density dependence at low population levels has been described for a range of animals and plants and is often termed an Allee effect. Our objective was to characterize how the Allee effect might reduce the invasive potential of this economically important pathogen. We developed a simple population model of T. indica that incorporates an Allee effect by calculating the probability of infection for different numbers of secondary sporidia in the infection court. An Allee effect is predicted to be important at the frontier of an invasion, for establishment of new foci by a small population of teliospores, and when the environment is nonconducive for the production of secondary sporidia. Using estimated model parameter values, we demonstrated a theoretical threshold population size below which populations of T. indica were predicted to decline rather than increase. This threshold will vary from season to season as a function of weather variables and their effect on the reproductive potential of T. indica. Deployment of partial resistance or use of fungicides may be more useful if they push population levels below this threshold.  相似文献   

Major outer membrane proteins of Brucella spp.: past,present and future   总被引：16，自引：0，他引：16  

Cloeckaert A  Vizcaíno N  Paquet JY  Bowden RA  Elzer PH 《Veterinary microbiology》2002,90(1-4):229-247

The major outer membrane proteins (OMPs) of Brucella spp. were initially identified in the early 1980s and characterised as potential immunogenic and protective antigens. They were classified according to their apparent molecular mass as 36–38 kDa OMPs or group 2 porin proteins and 31–34 and 25–27 kDa OMPs which belong to the group 3 proteins. The genes encoding the group 2 porin proteins were identified in the late 1980s and consist of two genes, omp2a and omp2b, which are closely linked in the Brucella genome, and which share a great degree of identity (>85%). In the 1990s, two genes were identified coding for the group 3 proteins and were named omp25 and omp31. The predicted amino acid sequences of omp25 and omp31 share 34% identity. The recent release of the genome sequence of B. melitensis 16 M has revealed the presence of five additional gene products homologous to Omp25 and Omp31. The use of recombinant protein technology and monoclonal antibodies (MAbs) has shown that the major OMPs appear to be of little relevance as antigens in smooth (S) B. abortus or B. melitensis infections i.e. low or no protective activity in the mouse model of infection and low or no immunogenicity during host infection. However, group 3 proteins, in particular Omp31, appear as immunodominant antigen in the course of rough (R) B. ovis infection in rams and as important protective antigen in the B. ovis mouse model of infection. The major OMP genes display diversity and specific markers have been identified for Brucella species, biovars, and strains, including the recent marine mammal Brucella isolates for which new species names have been proposed. Recently, Omp25 has been shown to be involved in virulence of B. melitensis, B. abortus and B. ovis. Mutants lacking Omp25 are indeed attenuated in animal models of infection, and moreover provide levels of protection similar or better than currently used attenuated vaccine strain B. melitensis Rev.1. Therefore, these mutant strains appear interesting vaccine candidates for the future. The other group 3 proteins identified in the genome merit also further investigation related to the development of new vaccines.  相似文献   

Acute cortisol responses of calves to scoop dehorning using local anaesthesia and/or cautery of the wound   总被引：1，自引：0，他引：1  

SP SYLVESTER  DJ MELLOR  KJ STAFFORD  RA BRUCE  RN WARD 《Australian veterinary journal》1998,76(2):118-122

Objective To measure plasma cortisol responses in calves dehorned using a scoop after administration of local anaesthesia and/or cautery of the wounds.
Design A physiological study with controls.
Procedure There were six treatments: control handling with and without local anaesthesia, dehorning, dehorning after local anaesthesia, dehorning followed by wound cautery, and dehorning after local anaesthesia followed by wound cautery. Blood samples were taken before and after dehorning.
Results Dehorning caused an increase in plasma cortisol concentrations, which decreased a little to plateau values and then declined to pretreatment values 3 to 4 h after dehorning. The peak was smaller after local anaesthesia was administered but when its effects wore off, cortisol concentrations increased and thereafter were similar to those in the dehorned animals. The combination of local anaesthesia and cautery resulted in a plasma cortisol response similar to those in control calves with or without local anaesthesia.
Conclusions If plasma cortisol concentrations reflect the distress being experienced by the calves, then local anaesthesia reduces the acute distress for about 3 h after dehorning but not during the subsequent 3 to 4 h. Combining local anaesthetic and cautery prevented the significant increase in plasma cortisol following dehorning and may eliminate the acute distress caused by scoop dehorning.  相似文献   

Successful medical treatment of splenic abscesses in a horse     

CM STEEL  RA LONSDALE  JR BOLTON 《Australian veterinary journal》1998,76(8):541-542

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