An assessment of the use of remote sensing to map habitat features important to sustaining lamprey populations

• 1. This study describes the use of colour aerial photography and Airborne Thematic Mapper (ATM) multispectral imagery (420–1050 nm) to map gravel‐bed river habitats important to sustaining river lamprey (Lampetra fluviatilis) — an aquatic species with high conservation interest in Europe. The accuracy of the remote sensing approach was assessed by comparing the output from automated mapping of physical habitat features using image analysis and GIS and habitat maps derived from field survey.
• 2. Unsupervised classification of the aerial photography and ATM imagery mapped hydraulic habitat such as pools and riffles with overall accuracies of 57% and 65.5% respectively. Submerged sand and silt deposits, which are important to river lamprey ammocoetes could not be identified on the imagery by simple unsupervised or supervised classification. They could be mapped indirectly, however, by association between their presence and morphological attributes such as backwaters and embayments in the bank profile detectable on the imagery. Remotely determining the likely presence and location of lamprey ammocoete habitat can be useful in planning detailed electrofishing campaigns to estimate lamprey densities, to assess conservation status and any change over time, and to determine the need for restoration strategies.
• 3. The results suggest that on rivers wider than 20 m without a continuous wooded riparian fringe, and where there is good quality imagery, it is possible to automate mapping of physical habitat features important to many river species with high nature conservation interest. As a result organizations charged with monitoring and conserving river species should consider investing in airborne imagery covering river systems of high conservation value.

Copyright © 2007 John Wiley & Sons, Ltd.     

Experiences with a vaccine being developed for the control of swine dysentery

SUMMARY A prototype vaccine that is being developed for the control of swine dysentery (SD) was tested in two groups of experimental pigs. Vaccination induced high circulating antibody titres against the aetiological agent, Serpulina (Treponema) hyodysenteriae .
Pigs in the first trial were vaccinated twice before being challenged orally with the bacteria. Five of 6 unvaccinated animals developed dysentery within a fortnight of challenge, but only 1 of 6 vaccinated pigs showed signs of disease at this time. Unexpectedly, 1 mo after challenge, the surviving unvaccinated pig and 2 remaining healthy vaccinated animals succumbed to the disease. The reason for the development of this late-onset form of dysentery was not clear.
In the second trial, 8 pigs were vaccinated 3 times. Only 2 of these animals (25%) developed severe dysentery after being mixed with infected pigs, whereas 7 of 8 (88%) unvaccinated control pigs in the same pen became diseased. The late-onset form of dysentery was not observed.
The prototype vaccine for SD provided a useful level of protection, and could be used in programs to control the disease in Australia.     

The adoption of management and husbandry procedures by Western Australian pig farmers

A postal survey was conducted to determine the management and husbandry procedures adopted by a sample of 101 Western Australian pig farmers. Seventy seven replies were received and analysed. Over 80% of farmers vaccinated breeding stock against leptospirosis and erysipelas, 35% vaccinated against parvo virus and 15% vaccinated against Escherichia coli. Most farmers used antibiotics: 72% incorporated them into their pig diets and 60% used parenteral antibiotics. Fifty three per cent of farmers reported that they regularly used a veterinarian. Over 59% of piggeries had another piggery located within 10 km, thus increasing the possibility for disease transmission between herds. It is concluded that there is potential for veterinarians to offer advice to pig farmers, particularly on disease control measures and adoption of technological advances.     

The incidence, cost and factors associated with foot lameness in dairy cattle in south-western Victoria

A survey of 73 dairy farms in south-western Victoria was conducted to assess the cost and mean herd incidence of foot lameness for the period from calving to the end of November, 1985, and to identify the herd, management and environmental factors associated with foot lameness. The mean herd size was 125 cows (range 82 to 220). Lameness occurred in 64 (88%) herds, and the mean herd incidence was 7.0% (range 0.0 to 30.9%). The main clinical signs associated with lameness were the presence of overworn and/or bruised soles, or stones lodged in the interdigital cleft. Factors associated with lameness were: property and herd size, age of cow, bail feeding, voluntary entry into the bails, and features of the farm track including its length, the presence of steep slopes, the type of surface material, presence and treatment of broken sections and maintenance including rolling history. The association of these factors with specific clinical signs was examined. The mean cost was estimated to be $42.90 per lame cow due to loss of production, treatment, the culling or death of lame cows, and extra man hours spent managing lame cows. It was concluded that the site, construction, maintenance and use of the farm track were of major importance to the incidence of lameness in herds in this area and recommendations for reducing lameness are made.