A predictive model for early-warning of Septoria leaf blotch on winter wheat

Disease–weather relationships influencing Septoria leaf blotch (SLB) preceding growth stage (GS) 31 were identified using data from 12 sites in the UK covering 8 years. Based on these relationships, an early-warning predictive model for SLB on winter wheat was formulated to predict the occurrence of a damaging epidemic (defined as disease severity of 5% or > 5% on the top three leaf layers). The final model was based on accumulated rain > 3 mm in the 80-day period preceding GS 31 (roughly from early-February to the end of April) and accumulated minimum temperature with a 0°C base in the 50-day period starting from 120 days preceding GS 31 (approximately January and February). The model was validated on an independent data set on which the prediction accuracy was influenced by cultivar resistance. Over all observations, the model had a true positive proportion of 0.61, a true negative proportion of 0.73, a sensitivity of 0.83, and a specificity of 0.18. True negative proportion increased to 0.85 for resistant cultivars and decreased to 0.50 for susceptible cultivars. Potential fungicide savings are most likely to be made with resistant cultivars, but such benefits would need to be identified with an in-depth evaluation.     

Impact of cypermethrin on feeding behaviour and mortality of the spider Pardosa amentata in arenas with artificial 'vegetation'

Pesticides can modify invertebrate movement and feeding behaviour which could reduce predation in agroecosystems. Previous assays have exposed the spider Pardosa amentata (Clerck) to the synthetic pyrethroid cypermethrin and monitored prey items consumed in small containers (requiring very little movement to capture prey). The current study used larger arenas containing artificial 'vegetation' (a plastic analogue) to encourage spiders to hunt and capture prey. The period 24 h after exposure produced greatest variability in prey item consumption between treatments and was used to examine treatment effects. At this time, cypermethrin reduced prey consumption rates but these effects did not persist. Findings did not suggest that the presence of artificial vegetation in arenas modified prey consumption rates, which was consistent for individuals treated with cypermethrin and a control group. This is despite the majority of pesticide-treated individuals exhibiting both ataxia and paralysis of the hind legs (these effects persisting for a maximum of 3 and 6 days respectively). These findings were consistent for both sexes. Spider longevity under starvation conditions was not significantly reduced by cypermethrin exposure but overall females survived longer than males. The findings are discussed in the context of the arenas used and the ecology of this common predator.     

A study of the efficacy of topical and systemic therapy for the treatment of feline Microsporum canis infection.

Microsporum canis infection was induced in 21 healthy SPF-derived cats. Once infection was established (4 weeks after inoculation) the cats were divided into three equal groups housed in separate rooms and monitored for 16 weeks. During this time, group A cats received oral griseofulvin at approximately 50 mg/kg daily and were shampooed twice weekly with a product containing chlorhexidine and miconazole. Group B cats were treated with griseofulvin alone, and group C cats served as untreated controls. The cats were examined on a weekly basis and the severity of lesions was scored semi-quantitatively. In addition, hair samples were collected from each cat on a weekly basis by the MacKenzie brush technique and by the sticky-tape method. A semi-quantitative scoring system was also used for the assessment of fungal (M canis) growth. Generally, significant differences in clinical scores were not seen between the groups although at weeks 3, 4 and 11 there was a significant difference (P< or =0.015) with cats in group A having significantly lower median scores than those in group C. Median times to clinical resolution (return of clinical scores to zero) in groups A, B and C were at treatment weeks 2, 9 and 12, respectively (P>0.05). Median times for mycological resolution (persistently negative culture results) for groups A, B and C were at treatment weeks 2, 9 and 12, respectively, for the MacKenzie brush technique and at weeks 4, 8 and 12 for the sticky-tape technique. For both these results, the groups differed significantly (P< or =0.001) and in both instances group A had significantly more rapid resolution than groups B or C. Median culture scores were significantly different between the three groups using one or both of the sampling techniques at week 2 through to week 12 of treatment with median scores for either group A alone, or groups A and B being significantly lower than group C (P< or =0.026). These results showed a benefit from the addition of twice-weekly chlorhexidine-miconazole shampooing to systemic griseofulvin therapy alone in the treatment of M canis infected cats.     

EFFECTS OF LOW-LEVEL EXPOSURE TO IONIZING RADIATION: CURRENT CONCEPTS AND CONCERNS FOR VETERINARY WORKERS*

The issue of biological effects caused by low-level exposure to ionizing radiation (0.1Sv/yr or 10 rem) is a concern of veterinary radiologists, clinicians and radiotherapists. Cellular damge from ionizing radiation is mediated by injury to DNA, some of which can be repaired. The most important harmful effects attributed to low-level exposure are carcinogenesis and mutation. Ionizing radiation may also cause embryonic and fetal damage, life span shortening and cataractogenesis. The estimated excess risk of mortality for all human cancers is 0.8% (800 deaths per 100,000) per 0.10 Sv of acute exposure; at low dose-rates, risk is presumed to be less. Ionizing radiation increases the frequencey of spontaneous genic and chromosomal mutations in man and animals. Studies of atomic bomb survivors imply that at least 1 Sv would be needed to double the spontaneous mutation rate for acute exposure to low-LET radiation. However, the doubling dose for chronic, low-level exposure may be 4 Sv or more. The human embryo and fetus are sensitive to excessive doses of ionizing radiation, with mental retardation the main concern in the low dose range. Paradoxically, there is scientific evidence that in some instances, chronic low-level exposure to ionizing radiation causes a beneficial or hormonic effect. For veterinary workers, occupational exposures appear to be well below the maximum permissible dose limit and the risk or probability of harmful effects is low if stringent radiation safety practices are maintained.     

Pasteurella haemolytica as a co-pathogen in pullets and laying hens

Pasteurella haemolytica was isolated from internal organs of laying hens and pullets of four flocks in which five incidents of increased mortality had occurred. There was inflammation of the trachea in all cases, and infectious laryngotracheitis virus was identified in three of the incidents. Rapid response to antimicrobial therapy was seen in two out of three outbreaks in the pullets. P. haemolytica was regarded as a significant secondary invader in these cases.     

The contribution of livestock to urban resilience: the case of Bamako,Mali

Urban livestock keeping is increasing in many sub-Saharan African cities, but detailed contextual information on its extent, challenges, and potential is limited. A cross-sectional household study was done in 2010 in Bamako, Mali. Thirty-two of 67 quarters were randomly selected with selection probability proportional to the size of the human population of the communes. Questionnaire interviews were done with a head of household in 1141 households, comprising 19,816 people in total. Sheep were kept by 16% (95% CI 14–18), while 21% (95% CI 17–24) kept poultry. The sheep to human ratio was 4:100, with an extrapolated city-wide population of 67,636 sheep (95% CI 61,018–75,595). The poultry to human ratio was 11:100, with an extrapolated city-wide population of 191,802 chickens (95% CI 176,212–208,772). For urban livestock holders, household-level enterprise gross margins were calculated for sheep production at USD 103 and poultry production at USD 50 annually. The annual gross margin was estimated at USD 35 per sheep and USD 17 per chicken. Based on these figures, the city-wide urban livestock total gross margin for Bamako in 2010 was estimated at USD 5.6 million. Detailed population data help clarify the urban livestock animal human interface in diverse contexts and highlight the important contributions that urban small-holder production adds to food security and resilience. The potential for urban livestock production informs decision-makers in developing adapted, sustainable policies in resource-constrained environments.

     

A microbiological assay to estimate the antimicrobial activity of parenteral tildipirosin against foodborne pathogens and commensals in the colon of beef cattle and pigs

Tildipirosin (TIP) is a novel 16‐membered‐ring macrolide authorized for the treatment of bovine and swine respiratory disease. The pH dependency of macrolide antimicrobial activity is well known. Considering that the pH in the colon contents of growing beef cattle and pigs is usually below pH 7.0, the minimum inhibitory concentrations (MIC) of TIP against foodborne bacterial pathogens such as Campylobacter (C.) coli, C. jejuni and Salmonella enterica and commensal species including Enterococcus (E.) faecalis, E. faecium and Escherichia coli were determined under standard (pH 7.3 ± 1) or neutral as well as slightly acidic conditions. A decrease in pH from 7.3 to 6.7 resulted in an increase in MICs of TIP. Except for the MICs > 256 μg/mL observed in the resistant subpopulation of the C. coli and the Enterococcus species, the MIC ranges increased from 2–8 μg/mL to 64–> 256 μg/mL for Salmonella enterica and E. coli, from 8–16 μg/mL to 32–128 μg/mL for the two Campylobacter species, and from 4–32 μg/mL to 128–> 256 μg/mL for both Enterococcus species. To estimate the antimicrobial activity of TIP in the colon contents of livestock during recommended usage of the parenterally administered TIP (Zuprevo^®), and to compare this with the increased MICs at the slightly acidic colonic pH, we developed and validated a microbiological assay for TIP and used this to test incurred faecal samples collected from cattle and pigs. Microbiological activity of luminal TIP was determined in aqueous supernatants from diluted faeces, using standard curves produced from TIP‐spiked faecal supernatants. The limit of quantification (LOQ) for TIP was 1 μg/mL (ppm). In a cattle study (n = 14), 3 of 28 faecal samples collected 24 and 48 h post‐treatment were found to contain TIP above the LOQ (concentrations of 1.3–1.8 ppm). In another cattle study (n = 12) with faecal samples collected at 8, 24 and 48 h post‐treatment, TIP concentrations were above the LOQ in 4 of the 8 h samples (1.2–2.6 ppm) and one of the 24‐h samples (1.3 ppm). In a pig study (n = 12) with faecal samples collected 24, 48 and 72 h post‐treatment, only one sample contained TIP above the LOQ (concentration 1.5 ppm). In another pig study (n = 12), with samples collected at 8, 24 48 and 96 h post‐treatment, TIP concentrations were above the LOQ in one 8‐h sample (1.1 ppm) and two 24‐h samples (2.3 and 2.5 ppm). None of the 48‐h and 96‐h samples from these 4 studies contained measurable TIP concentrations. Thus, in cattle and pigs, only a small fraction of faecal samples collected up to 24 h postdosing contained measurable microbiologically active TIP, with its maximum limited to 2.6 μg/mL. This is several log₂ dilution steps below the MICs of TIP against foodborne pathogens and commensals collected under acidic conditions comparable with those in the colonic contents and may explain a lack of intestinal dysbacteriosis with parenteral tildipirosin in livestock.