Effects of disturbance and habitat loss on papyrus-dwelling passerines

Throughout the world, but particularly in tropical regions habitat loss and disturbance are considered detrimental to biodiversity. We examine the effects of disturbance by harvesting, burning and habitat fragmentation on six bird species associated with papyrus (Cyperus papyrus) swamps. The presence or absence of these species was verified in 93 wetlands in southern Uganda between June and August 2003. Disturbance was estimated directly by observation and indirectly from examining vegetation structure. Habitat fragmentation was quantified by delineating swamps on Landsat ETM images and applying ‘Fragstats’ to calculate relevant patch metrics. The occurrence of all six species was affected positively by increased swamp size, but birds were more likely to occur in small swamps at high altitude. The shape and proximity of swamps to neighbouring wetlands had little effect on occurrence. As altitude, habitat fragmentation and disturbance were correlated, determining avian responses to disturbance was problematic. However, the occurrence of all species was affected by disturbance, often showing unimodal responses, if disturbance was not considered in conjunction with habitat fragmentation. When the effects of habitat fragmentation and disturbance were analysed together, only the occurrences of papyrus yellow warbler and white-winged warbler were affected (positively) by disturbance. Results suggest that papyrus-dwelling passerines, except papyrus gonolek, are tolerant of low intensities of disturbance, a novel finding in the tropics. We recommend that policy-makers do not prohibit harvesting, thus generating good will and encouraging rural householders to comply with additional conservation policy.     

Serological response to Actinobacillus pleuropneumoniae serovar 7 infection in a commercial pig herd

Serological responses to Actinobacillus pleuropneumoniae serovar 7 infection were monitored by enzyme-linked immunosorbent assay in a cohort of 66 pigs between weaning and market. Antibody concentrations were high (63/65 seropositive) at 4 weeks of age but declined to low levels from 8 to 12 weeks. Mean antibody concentrations rose significantly (p less than 0.001) between 12 and 23 weeks. Between 8 and 23 weeks of age, 33 (51.5%) of 64 surviving pigs seroconverted to A pleuropneumoniae serovar 7. Peak antibody concentrations in the seroconverting pigs usually (28/33) occurred at 23 weeks. Seroconversion to A pleuropneumoniae during the grower/finisher phase was not significantly associated (p greater than 0.05) with passive antibody concentrations at 4 weeks of age, lack of vaccination against Mycoplasma hyopneumoniae, or weaning weight. Pleuropneumonic lesions were evident at slaughter in 4 (6.3%) of 64 pigs. A pleuropneumoniae serovar 7 was isolated from 2 of 4 lungs with pleuropneumonia and from another lung with lesions considered typical of enzootic pneumonia.     

Field-Induced Layering of Colloidal Crystals

An electrohydrodynamic methodology has been developed that makes possible the precise assembly of two- and three-dimensional colloidal crystals on electrode surfaces. Electrophoretically deposited colloidal particles were observed to move toward one another over very large distances (greater than five particle diameters) to form two-dimensional colloidal crystals for both micrometer- and nanometer-size particles. This coalescence of particles with the same charge is opposite to what is expected from electrostatic considerations and appears to result from electrohydrodynamic fluid flow arising from an ionic current flowing through the solution. The ability to modulate this "lateral attraction" between particles, by adjusting field strength or frequency, facilitates the reversible formation of two-dimensional fluid and crystalline colloidal states on the electrode surface. Further manipulation allows controlled structures to be assembled.     

Recent developments in the management of anthelmintic resistance in small ruminants – an Australasian perspective

Abstract

There have been a number of significant advances in recent years to the theory and practice of managing anthelmintic resistance in sheep in Australasia. The general principles of resistance management are, firstly identification and mitigation of high-risk practices, secondly using effective anthelmintics, and thirdly maintaining a refuge of unselected parasites. The first of these principles has been updated recently with the findings from a series of farm-based trials in New Zealand, in which the economic benefits of both short- and long-acting anthelmintic treatments in ewes pre-lambing were found to be inconsistent and not always positive. There have also been significant changes to the second principle, particularly given the introduction of new active families onto the market. Evidence continues to favour the use of combination products to maximise efficacy and delay the onset of treatment-failure. Many farmers have readily accepted the effectiveness of maintaining a refuge of unselected parasites; the challenge for researchers and advisers is now to improve adoption of properly designed and implemented resistance management programmes. A recently completed education programme in New Zealand has demonstrated that when this is achieved, then anthelmintic resistance can be controlled, and in many cases reduced in severity.     

Acute enteritis and deaths in sheep from Salmonella hindmarsh associated with oral dosing with zinc oxide

Abstract

Extract

Madam:– The administration of zinc salts to sheep at the time they are exposed to spores of Pithomyces chartarum will reduce the amount of liver damage from the mycotoxin contained in these spores.(7 Smith, B.L., Embling, P.P., Towers, N.R., Wright, D.E. and Payne, E. 1977. The protective effect of zinc sulphate in experimental sporidesmin poisoning of sheep. N.Z. vet. J., 25: 124–127. [Taylor &; Francis Online], [Web of Science ®] , [Google Scholar])(10 Towers, N.R., Smith, B.L., Wright, D.E. and Sinclair, D.P. 1975. Preventing facial eczema by using zinc. Proc. Ruakura Farmers Conference 1975, : 57–61.  [Google Scholar])(11 Towers, N.R., Wright, D.E., Aitken, W.M., Smith, B.L., Sim, A.L. and Sinclair, D.P. 1976. Zinc and facial eczema. Proc. Ruakura Farmers Conference 1976, : 65–68.  [Google Scholar]) It is a recommended practice in facial eczema susceptible areas of New Zealand.(9 Towers, N.R. and Smith, B.L. 1983. Facial eczema. Zinc dosing for prevention. Revised recommendations 1984, AgLink FPP 496 end revise [Google Scholar]) We wish to report a suspected outbreak of salmonellosis that occurred only in a ZnO-dosed group of trial animals and suggest that there may be an association between ZnO administration and salmonellosis.     

An overview of dropped hock syndrome cases in New Zealand cattle

ABSTRACT

Case history: Data were collected from 47 outbreaks of dropped hock syndrome (DHS) that were reported by veterinarians in New Zealand to the Ministry for Primary Industries between October 2012 and August 2017. There were 181 affected dairy cows from 44 farms. Of those with records, all 86 were aged between 2–3 years-old, and 4/94 (4%) were Friesian, 56/94 (60%) were Jersey and 33/94 (35%) were Jersey/Friesian cross. Of the 47 outbreaks, 45 (96%) occurred during winter and 37 (79%) in the South Island.

Clinical findings: Of 151 cases with records, hindlimb weakness (117 cows), shortened gait (112 cows) and dropped hocks (106 cows) were most commonly reported, with 110 cases being bilaterally affected. The level of diagnostic work-up and the data recorded by veterinarians for each outbreak were highly variable. Creatine kinase and aspartate aminotransferase activities were reported for 22 cases and were within normal ranges for cows with mild disease but increased in cows with severe disease. Concentrations of Cu in serum and liver were below normal for 13/22 and 9/10 cows, respectively, from six outbreaks. Of 41 cows with records for clinical outcomes, 12 had complete resolution, 18 had partial resolution, and 11 had no resolution.

Pathological findings: Post-mortem data were available from 26 cases. Muscle necrosis and haemorrhage of the origin of the gastrocnemius muscle were the key gross findings. In 14 cows with records for muscle histopathology, myodegeneration and recent haemorrhage were observed, and connective tissue pathology was reported to predate muscular pathology in seven cases.

Diagnosis: DHS appeared to be a degenerative rather than inflammatory condition primarily affecting the connective tissue of the hind limb, especially at the dense collagen interfaces of the gastrocnemius. Although no evidence of neuropathy was found, this cannot definitively be ruled out as a potential cause.

Clinical relevance: A more standardised and systematic approach to investigating cases and recording case data is required to make robust inferences about the aetiology, risk factors, and treatment interventions for DHS.     

Field tests of a linear gradient system for exposure of row crops to S02 and HF

An exposure system for exposing plants to gradients of gaseous air pollutants in the field was tested using sulfur dioxide SO₂ and hydrogen fluoride (HF). Well defined linear gradients of SO₂ concentration and HF flux were easily produced and were repeatable from exposure to exposure. The gradients were altered by wind speed and direction, but in tightly closed canopies, the alterations were minor. This system has many advantages: a graded series of exposures can be conducted in a small area, plants may be grown using accepted cultural practices, the cost of the apparatus is low, and more than one pollutant can be used, either concurrently or countercurrently. Disadvantages include the requirement for an intensive air monitoring network and an unnatural vertical pollutant profile in the canopy. The gradient system should be used as a supplement to open-top chambers, and not as a replacement for them.