Epidemiology of Salmonella enterica serovars enteritidis and Typhimurium in animals and people in Scotland between 1990 and 2001

Two serovars of salmonella which are currently of particular importance in both human and animal infections are Salmonella enterica serovars Enteritidis phage type 4 (PT4) and Typhimurium definitive type 104 (DT104). This paper describes the trends in the relationships between the levels of infection of people and a range of farm animal species with these two serovars and explores some of the reasons behind them. In 1996, there was a peak of 520 reports of S Typhimurium DT104 infection in people in Scotland, but the number has decreased every year since, to 96 in 2001. In cattle the incidence of S Typhimurium DT104 also peaked in 1996, with 138 incidents, and it has similarly decreased every year to 2001 when there were 10 reported incidents. Similar declines have been observed in its incidence in sheep and pigs. In people the number of reports of S Enteritidis PT4 peaked in 1997 at 1684 and then declined to 457 in 2001. In chickens, the number of reports of S Enteritidis PT4 peaked in 1998 at 34 incidents, but no incidents were reported in the following three years.     

Lignin deposition and associated changes in anatomy,enzyme activity,gene expression,and ruminal degradability in stems of tall fescue at different developmental stages

Stem tissues of tall fescue (Festuca arundinacea Schreb.) were sampled at three elongation stages and three reproductive stages. Anatomical analysis showed the deposition of guaiacyl (G) and syringyl (S) lignin during plant development and the formation of a lignified sclerenchyma ring. A dramatic increase in Klason lignin content was found from elongation stage to reproductive stage. Lignin composition analyzed by gas chromatography-mass spectrometry revealed that S lignin content and S/G ratio increased with stem development, but contents of p-hydroxyphenyl (H) and G lignins decreased during the same period. S lignin content and S/G ratio also increased from the younger upper internode down to the older basal internode of the stem, but G and H lignin decreased in parallel. Relative O-methyltransferase activities increased during stem development and in parallel with the lignification process of stem. The pattern of enzyme activity during development varied with the choice of substrate, with highest activities seen when substrates were caffeoylaldehyde and 5-hydroxyferulic acid, and lowest activities were seen when caffeic acid and 5-hydroxyconiferyl alcohol were used as substrates. The expression of caffeic acid O-methyltransferase and cinnamyl alcohol dehydrogenase genes increased during the stem elongation stage and remained at high levels during the reproductive stages. The changes at anatomical, metabolic, and molecular levels during plant development were closely associated with lignification and degradability. This study provides an integrated picture of the molecular and chemical events that accompany changes in lignin deposition and ruminal degradability.     

The effects of stock crate design and stocking density on environmental conditions for lambs on road transport vehicles

AIM: The aim of this study was to evaluate the potential of variations in stock crate design (especially ventilation) and stocking density on road transport vehicles for reducing the risk of environmental stress for lambs during long-haul transport in hot weather. METHODS: In Experiment 1, lambs were transported on vehicles fitted with either a newer-design aluminium crate comprising a three-deck truck and four-deck trailer, or an older-design, more open, steel crate of a three-deck truck and three-deck trailer. In Experiment 2, lambs were transported on newer-design vehicles at either standard stocking density (0.20 m2 per 35 kg lamb) or at a 20% lower density (0.26 m2 per 35 kg lamb). In each experiment, each journey was replicated twice and consisted of travel periods and stationary periods designed to emulate conditions associated with an inter-island ferry crossing. Air ammonia concentrations and temperature and humidity were monitored within six pens on each vehicle, and the temperature-humidity index (THI) was calculated. RESULTS: Ammonia concentrations were variable and generally 50 ppm, and did not vary significantly with treatment. The THI increased when the vehicles were stationary, especially under conditions designed to emulate an enclosed ferry deck. The ambient temperature during Experiment 1 was moderate (up to 21 degrees C), and THI was slightly lower in the older-design crate. High ambient temperatures (up to 33 degrees C) were present during Experiment 2, and THI was significantly lower at the lower stock density. During a 3-h stationary period, the peak THI at standard stocking density was 91.0, compared with 84.9 for the low density treatment (p<0.001). CONCLUSIONS: For standard road transport vehicles used for long-haul transport of lambs, lowered loading density may be of considerable benefit in alleviating conditions that increase the risk of lamb deaths during inter-island transport on hot days.     

Efficacy of extended pirlimycin hydrochloride therapy for treatment of environmental Streptococcus spp and Staphylococcus aureus intramammary infections in lactating dairy cows

Fifty-one chronically infected lactating dairy cows were used to evaluate the efficacy of extended pirlimycin therapy regimens for treatment of intramammary infections by environmental Streptococcus spp and Staphylococcus aureus. Cows (n = 47) with one or more infected mammary quarters were blocked by parity and randomly allocated to one of three groups for treatment with pirlimycin (50 mg/mammary quarter) as follows: one treatment per day for 2 days (n = 36 infected mammary quarters); one treatment per day for 5 days (n = 36 infected mammary quarters); and one treatment per day for 8 days (n = 20 infected mammary quarters). Four cows with nine infected mammary quarters were included as untreated controls. Milk samples from each mammary quarter were collected 7 days before treatment, immediately before treatment, and weekly for 4 weeks after the final treatment for microbiological evaluation. A bacteriologic cure was defined as a treated, infected quarter that was bacteriologically negative for the presence of previously identified bacteria at weekly intervals after treatment. Efficacy of pirlimycin therapy against intramammary infections caused by environmental Streptococcus spp and S. aureus was 44.4%, 61.1%, and 95.0% for the 2-, 5-, and 8-day treatment regimens, respectively. None of the infections in the untreated control quarters was cured. Significant differences in efficacy were detected between all pirlimycin groups and the untreated control group, between the 8- and 2-day treatment regimens, and between the 8-day and 5-day treatment regimens (P < or = .05). Results of this study indicate that extended pirlimycin therapy was effective in eliminating intramammary infections caused by environmental streptococci and S. aureus in lactating dairy cows.     

PrP genotype and lamb birth weight in a scrapie-free environment: Is there an association?

The National Scrapie Plan (NSP) for Great Britain includes selective breeding programmes. These aim to reduce the frequencies of the ovine prion protein (PrP) genotypes at high risk of developing clinical disease (principally those containing the VRQ allele) within the national flock, and select for the low-risk ARR-containing genotypes. The aim of this work was to use available data from embryo transfer programmes in guaranteed scrapie-free environments to investigate whether there was a difference in lamb birth weight associated with the lamb's PrP genotype, which might affect survival. The first analysis utilised data from 355 Cheviot lambs born between 2001 and 2004. The analysis was then repeated using a larger data set of 737 Cheviot, Dorset and Suffolk lambs born between 1999 and 2003. The most important determinants of mean lamb birth weight were litter size, sex and recipient ewe breed, plus lamb breed in the three breed analysis. In both analyses the effects of all these variables are consistent and of the same order of magnitude. In the first analysis there was evidence for an apparent increase in mean lamb birth weight for the ARR-containing genotypes of 0.3 kg (95% C.I. 0.1–0.5 kg). Whereas, in the second data set there was evidence for a decrease in mean lamb birth weight for the VRQ-containing genotypes of − 0.6 kg (95% C.I. − 0.8 to − 0.4 kg). This had been masked in the first analysis by the categorisation of these genotypes with the ARQ/ARQ genotype. Within these flocks, in a scrapie-free environment, neither finding provides support for concerns that selection for low risk ARR-containing genotypes would be detrimental to lamb birth weight, which is considered to be the most important determinant of lamb survival. Extension of this work into field flocks, where scrapie-status cannot be easily assured, will require the collection of sufficient data to adjust for known direct effects as well as any additional potential confounding effects.     

Application and field validation of a PCR assay for the detection of Mycoplasma hyopneumoniae from swine lung tissue samples.

A PCR assay was validated for the detection of Mycoplasma hyopneumoniae in porcine lung tissue. The detection limit of the assay was 0.18 colony-forming units/g of lung sample spiked with M. hyopneumoniae. In field validation, 426 pigs from 220 cases were examined for M. hyopneumoniae infection by M. hyopneumoniae PCR and a fluorescent antibody (FA) test. In total, 103 pig lungs (24.2%) were positive in the PCR test, and 69 pig lungs (16.2%) were positive in the FA test, among which, 62 pigs were positive for both PCR and FA test. Most of the PCR-positive but FA test-negative cases had lesions compatible with M. hyopneumoniae infection. With Bayesian modeling, the diagnostic sensitivity and specificity of the PCR were determined to be 97.3% and 93.0%, respectively.     

Landscape improvement, or ongoing degradation – reconciling apparent contradictions from the arid rangelands of Western Australia

Recent quantitative site-based monitoring and qualitative aerial and ground traverses provide contrasting assessments of the health of much of the arid shrublands of Western Australia extensively grazed by livestock (‘rangelands’). Although these results seem incompatible, we explain the apparent contradictions based on landscape succession processes operating at multiple levels of ecological organisation. Specifically, we suggest that the intact areas in which site-based monitoring is conducted are contracting as catchment canalisation and desiccation increase. However, the impacts of these processes have not yet become manifest at the site scale. The site-based system addresses important regional questions. These relate to the large, relatively intact areas away from most active surface flows, which should be a focus for resource conservation, given practical limits to repairing widespread degradation with low management inputs. We provide a complementary set of questions to provide a more comprehensive audit of rangeland dynamics in the context of underlying hierarchical landscape patterns and processes that might threaten intact areas. We recognise the need to match questions and levels of ecological organisation and the implications these have for sampling. We also recognise the difficulty in producing concise statements of change for clients when reporting on complex ecological issues and processes. Without a clearly articulated, and well understood, hierarchical model of pattern and process within which apparently contradictory findings can be reported meaningfully, policy makers may be confused by the results, with the consequent risk of policy inaction.