Euthanasia of rabbits by intravenous administration of ketamine

Six New Zealand White rabbits (5 females and 1 male) were anesthetized with a combination of xylazine (4.3 mg/kg of body weight) and ketamine (29.1 mg/kg) administered IM. The rabbits were then attached to instruments that continuously monitored blood pressure and electrocardiographic and electroencephalographic values. Each rabbit was then administered a lethal dose of ketamine (600 mg, IV). Within 90 seconds after injection of the ketamine, brain death developed and the heart rate and blood pressure decreased greatly. Circulatory activity persisted for a maximum of 240 seconds. This method of euthanasia did not result in histopathologic changes in tissue specimens evaluated. Although death occurred rapidly, extensive muscle contractions made euthanasia of rabbits with ketamine aesthetically unacceptable. Therefore, this method would not be a suitable means of euthanasia for routine use in rabbits.     

An investigation of the safety of oral calcium formate in dairy cows using clinical, biochemical and histopathological parameters

AIM: To investigate the safety of orally administered calcium formate in dairy cows fed adequate amounts of good quality pasture. METHODS: Twelve mixed-age pasture-fed lactating dairy cows were randomly allocated to three groups (n=4 cows/ group). Group 1 served as untreated controls. Group 2 was treated orally with 400 ml of 13.4% (w/w) calcium as calcium chloride gel, four times at approximately 12-h intervals. Group 3 was treated orally with 350 ml of 11.4 % (w/w) calcium as a 48.6% aqueous suspension of calcium formate, four times at approximately 12-h intervals. Cows grazed good quality autumn ryegrass and white clover pasture throughout the trial. All cows were examined clinically each evening and a blood sample collected. Cows were slaughtered 75 h after the last treatment and viscera examined visually for lesions. Samples from the mid-fundic area of the abomasum of each cow were collected for histopathological examination. Blood samples collected pre and 90-h post-first treatment were analysed for serum haptoglobin and pepsinogen concentrations. RESULTS: No evidence of abnormality was detected by observation or clinical examination in any of the trial cows. Serum haptoglobin concentrations were basal for all groups pre-treatment and remained basal for Groups 1 and 3 post-treatment, but were elevated post-treatment for Group 2 (p=0.016). No differences in serum pepsinogen concentrations were detected between sampling times or treatment groups. One cow from Group 2 had several small (5 mm) abomasal ulcers present at necropsy. Another cow from the same group had histopathology suggestive of thrombosis and re-endothelialisation. CONCLUSIONS: Oral administration of calcium formate (350 ml of 48.6% aqueous suspension) administered on four occasions at 12-h intervals had no adverse effects on the four cows examined, and as such is considered a safe form of calcium supplementation in adult dairy cows.     

Occurrence and distribution of persistent organochlorine compounds in U.K. sewage sludges

A total of 444 sewage sludges, sampled from sewage treatment works in the U.K., were analyzed for polychlorinated biphenyls (PCB) and the organochlorine insecticides γ-Hexachlorocyclohexane (γ-HCH), aldrin, dieldrin and endrin. PCB, γ-HCH and dieldrin were found to occur more frequently and at higher concentrations in sewage sludges than aldrin and endrin. In order to investigate the temporal variation of these compounds in sewage sludge, three sewage treatment works were sampled at monthly intervals over an 18 mo period. PCB, γ-HCH and dieldrin were again the most frequently detected compounds. Concentrations of aldrin and endrin were only sporadically detected. The results of a serial correlation analysis of these data indicated that some short term correlation of PCB and dieldrin concentrations above and below the mean value was evident. The data acquired in the course of this survey have been compared with the results of similar work conducted previously in the U.K. and other countries. The possible implications of the presence of persistent organochlorine compounds in sewage sludges which are disposed to the environment are discussed.     

Physiological responses of ponderosa pine in western Montana to thinning, prescribed fire and burning season

Low-elevation ponderosa pine (Pinus ponderosa Dougl. ex. Laws.) forests of the northern Rocky Mountains historically experienced frequent low-intensity fires that maintained open uneven-aged stands. A century of fire exclusion has contributed to denser ponderosa pine forests with greater competition for resources, higher tree stress and greater risk of insect attack and stand-destroying fire. Active management intended to restore a semblance of the more sustainable historic stand structure and composition includes selective thinning and prescribed fire. However, little is known about the relative effects of these management practices on the physiological performance of ponderosa pine. We measured soil water and nitrogen availability, physiological performance and wood radial increment of second growth ponderosa pine trees at the Lick Creek Experimental Site in the Bitterroot National Forest, Montana, 8 and 9 years after the application of four treatments: thinning only; thinning followed by prescribed fire in the spring; thinning followed by prescribed fire in the fall; and untreated controls. Volumetric soil water content and resin capsule ammonium did not differ among treatments. Resin capsule nitrate in the control treatment was similar to that in all other treatments, although burned treatments had lower nitrate relative to the thinned-only treatment. Trees of similar size and canopy condition in the three thinned treatments (with and without fire) displayed higher leaf-area-based photosynthetic rate, stomatal conductance and mid-morning leaf water potential in June and July, and higher wood radial increment relative to trees in control units. Specific leaf area, mass-based leaf nitrogen content and carbon isotope discrimination did not vary among treatments. Our results suggest that, despite minimal differences in soil resource availability, trees in managed units where basal area was reduced had improved gas exchange and growth compared with trees in unmanaged units. Prescribed fire (either in the spring or in the fall) in addition to thinning, had no measurable effect on the mid-term physiological performance and wood growth of second growth ponderosa pine.     

Graph theory as an invasive species management tool: case study in the Sonoran Desert

Context

Biodiversity in arid regions is usually concentrated around limited water resources, so natural resource managers have constructed artificial water catchments in many areas to supplement natural waters. Because invasive species may also use these waters, dispersing into previously inaccessible areas, the costs and benefits of artificial waters must be gauged and potential invasion- and climate change-management strategies assayed.

Objectives

We present a network analysis framework to identify waters that likely contribute to the spread of invasive species.

Methods

Using the Sonoran Desert waters network and the American bullfrog (Lithobates catesbeianus)—a known predator, competitor, and carrier of pathogens deadly to other amphibians—as an example, we quantified the structural connectivity of the network to predict regional invasion potential under current and two future scenarios (climate change and management reduction) to identify waters to manage and monitor for invasive species.

Results

We identified important and vulnerable waters based on connectivity metrics under scenarios representing current conditions, projected climate-limited conditions, and conditions based on removal of artificial waters. We identified 122,607 km² of land that could be used as a buffer against invasion and 67,745 km² of land that could be augmented by artificial water placement without facilitating invasive species spread.

Conclusions

Structural connectivity metrics can be used to evaluate alternative management strategies for invasive species and climate mitigation.

     

A novel use of the lacunarity index to discern landscape function

Discerning the function of a landscape involves comparing landscape use with spatial patterns. To do this requires both quantification of landscape use and landscape pattern and a means of comparing the two. An index of lacunarity has been used to quantify spatial pattern (specifically, habitat contagion). We demonstrate a new way of using the lacunarity index to quantify landscape function as well. We calculated lacunarity to describe landscape patchiness of experimental landscapes with respect to patterns of habitat and non-habitat areas (the previous use of lacunarity) as well as to describe patterns of patch use by animals in those landscapes, irrespective of habitat-patch patterns (a novel application of lacunarity). We demonstrate a disparity between landscape pattern and landscape use. This finding suggests that drawing generalizations of, and making predictions about, how animals respond to landscape spatial structure may not be straightforward.     

Vitamin D doses for alpacas (Lama pacos)

OBJECTIVE: To assess the effectiveness of cholecalciferol (D3) doses for maintaining adequate vitamin D status in crias and adult female alpacas at pasture. DESIGN: A field experiment during winter and early spring in a herd on a farm in South Australia. ANIMALS AND PROCEDURE: Crias, usually less than 6 months of age and female alpacas, aged 2 to 6 years, were given a single subcutaneous dose of 0, 1000 or 2000 IU D3/kg body weight. Plasma concentrations of 25-hydroxycholecalciferol (25-OH D3), phosphorus, calcium and vitamins A and E and alkaline phosphatase activity were measured at intervals over a period of 16 weeks after treatment. RESULTS: Crias not given a vitamin D supplement had reduced growth rate during winter and one animal showed clinical signs of rickets. Vitamin D treatment had no effect on the body weight of mature females. Vitamin D supplements increased the 25-OH D3 and phosphorus concentrations in plasma of both crias and adult females; alkaline phosphatase activity was not affected by treatment. CONCLUSION: It is suggested that for alpacas in southern Australia a subcutaneous dose of 1000 IU D3/kg body weight to crias in late autumn and again in mid winter and to adult females in mid winter should prevent vitamin D inadequacy.     

识别假劣、失效兽药的简易方法

介绍了识别假劣、失效兽药的简易方法,包括假劣兽药的外观识别和部分失效兽药的识别,可供畜牧养殖者参考.     

Migratory gauntlets on oceanic islands: Watershed disturbance increases the cost of amphidromy

Migratory fishes can be threatened by conditions encountered along dispersal pathways that impede access to feeding or breeding grounds. In this study, we tested the hypothesis that amphidromous fishes are equally or more sensitive to conditions along dispersal pathways than conditions in primary residential habitats. We did so by conducting distribution‐wide population surveys of all five amphidromous gobies native to the Hawaiian Islands to assess responses to in‐stream habitat, invasive species and watershed land use. We used Redundancy Analyses to assess whether goby densities varied according to local, downstream or upstream conditions. We found that population densities of the two non‐climbing species (Eleotris sandwicensis, Stenogobius hawaiiensis) varied according to local land use and local habitat conditions. Greater densities of E. sandwicensis also were found in watersheds with greater forest cover upstream of survey sites. Lower densities of two species that migrate farther inland (Awaous stamineus, Sicyopterus stimpsoni) were observed in watersheds with greater anthropogenic land use downstream or at the stream mouth. Population densities of E. sandwicensis and both Sicydiine species (Lentipes concolor, S. stimpsoni) also were lower when non‐native Poeciliids were locally present or present downstream in the watershed. These findings suggest that densities of native Hawaiian amphidromous fishes are equally or more sensitive to conditions along migratory pathways relative to conditions in primary residential habitats. Thus, alleviating pressures by removing invasive species and restoring habitat along dispersal pathways could be effective approaches to increasing densities of amphidromous species, especially those that migrate farther inland to higher elevations.     

Lifelong population connectivity between large rivers and their tributaries: A case study of shovelnose sturgeon from the Mississippi and Wisconsin rivers

Fishes that depend on large‐river habitats have declined in many regions due to human alteration of both mainstems and tributaries. Conserving these species is often complicated by their dependence on long‐distance movements to complete their life cycle, but the location of key habitats is difficult to assess across multiple life history stages. Movement of large‐river fishes between mainstems and major tributaries is commonly observed, but the role of these exchanges at the population level is uncertain. We used shovelnose sturgeon (Scaphirhynchus platorynchus) as a case study for assessing the lifelong spatial ecology of large‐river fishes. Fin ray microchemistry data indicate that shovelnose sturgeon from the Mississippi and Wisconsin rivers represent a unified population that relies on connections among multiple large‐river habitats throughout life history. The tributary serves as an important spawning area, but fin ray chemistry data suggest larvae subsequently drift downstream to nursery habitats in the mainstem; an assertion that is supported by extensive field survey data. Our analyses underscore the lifelong importance of connections within river networks for maintaining viable populations of this, and likely other large‐river species that have been documented to use tributary habitats. These findings support a metapopulation perspective on species that depend on large‐river habitats, many of which are now highly altered and fragmented. For shovelnose sturgeon and species with similar life history, protecting or restoring linkages between mainstem rivers and their tributaries should be a conservation priority.