Using diffusion models to simulate the effects of land use on grizzly bear dispersal in the Rocky Mountains

Timber harvests proposed for Trail Creek Watershed, in southwestern Montana, U.S.A., have been opposed because grizzly bear (Ursus arctos horribilis) dispersal from northern Montana wildernesses into the Greater Yellowstone Ecosystem may be less likely. We used an individual-based model to simulate grizzly bear responses to: 1) region-level management practices represented by ownership patterns, and 2) watershed-level changes in habitat availability due to proposed harvests and road building. We assigned permeabilities (i.e., values that represent how easily a bear can move through a patch) to ownership blocks (region-level) and habitat patches (watershed-level) based upon a literature review, and used a correlated random-walk diffusion model to simulate movements. Simulated bears were placed into rasterized landscapes in a stratified random manner. At the regional level, bears moved 1500 times (i.e., 1530 km), and their destinations were tallied. At the watershed level, the number of moves required for bears to leave the watershed were tallied. Sensitivity analyses were used to determine the variability of the results with respect to changes in some parameters of interest (i.e., permeabilities of private lands, harvest permeabilities, and disturbance indices).With the permeability of private land set at 50 (range: 0 to 99), simulated grizzlies did not disperse from the Scapegoat and Bob Marshall Wildernesses into Yellowstone National Park (0 of 10000 simulated individuals). Under the assumptions of this model, a linkage between the wildernesses in northern Montana and Yellowstone does not appear to exist. However, a significant number of simulated grizzlies (41%) dispersed from Anaconda Pintler Wilderness, which is near Trail Creek Watershed, into the wilderness ES in eastern Idaho. A linkage may exist between these sites.At the watershed-level, removal of forest habitat under proposed Harvest I (1.77% of the watershed cut) led to simulated grizzlies using slightly more moves (i.e., 5.6%, P=0.042) to exit the watershed than under existing conditions. Harvests of 3.5% of the watershed (planned Harvest II) did not alter the number of moves required to exit the watershed (P=0.068). When disturbances associated with roads and harvests were also examined, large increases in number of movements required to exit the watershed occurred ( 151%, P=0.002). These analyses suggest that grizzly bears would be disturbed while timber harvests were ongoing, but that long-term changes in movement would not occur if roads were closed following harvests. The analyses demonstrate the utility of applying individual-based diffusion models to landscape-level movements of animals, and identifies the need for telemetry studies to determine movement rates through specific habitats.     

Pharmacokinetics of marbofloxacin in blue and gold macaws (Ara ararauna)

OBJECTIVE: To determine the pharmacokinetics of marbofloxacin after single IV and orally administered doses in blue and gold macaws. ANIMALS: 10 healthy blue and gold macaws. PROCEDURES: In a crossover study, marbofloxacin (2.5 mg/kg) was administered orally (via crop gavage) to 5 birds and IV to 5 birds. Blood samples were obtained at 0, 0.5, 1, 3, 6, 12, 24, 48, 72, and 96 hours after marbofloxacin administration. After a 4-week washout period, the study was repeated, with the first 5 birds receiving the dose IV and the second 5 birds receiving the dose orally. Serum marbofloxacin concentrations were quantitated by use of a validated liquid chromatography-mass spectrometry assay. RESULTS: After oral administration, mean +/- SD area under the curve was 7.94 +/- 2.08 microg.h/mL, maximum plasma concentration was 1.08 +/- 0.316 microg/mL, and bioavailability was 90.0 +/- 31%. After IV administration of marbofloxacin, the apparent volume of distribution was 1.3 +/- 0.32 L/kg, plasma clearance was 0.29 +/- 0.078 L/h/kg, area under the curve was 9.41 +/- 2.84 microg.h/mL, and the harmonic mean terminal half-life was 4.3 hours. CONCLUSIONS AND CLINICAL RELEVANCE: Single IV and orally administered doses of marbofloxacin were well tolerated by blue and gold macaws. The orally administered dose was well absorbed. Administration of marbofloxacin at a dosage of 2.5 mg/kg, PO, every 24 hours may be appropriate to control bacterial infections susceptible to marbofloxacin in this species.     

Puncture and drainage of the subordinate follicles at timed artificial insemination prevents the risk of twin pregnancy in dairy cows

The objective of this study was to determine whether fluid drainage from the subordinate follicles by ovum pickup procedures prevents the risk of twin pregnancy without reducing the fertility of the cow. Lactating dairy cows with at least two follicles over 12 mm diameter located one on each ovary and selected from synchronized groups for fixed‐time insemination were assigned to a Control (n = 49) or Drainage (n = 49) group. The largest follicle was considered as the dominant follicle. Draining of all subordinate follicles (≥10 mm) was performed in the Drainage group. All drained follicles developed as a corpus luteum 7 days later. In the Control cows, the presence of two corpora lutea (55.1%) was lower (p = .003) than those in the Drainage cows (87.8%), whereas the incidence of twin pregnancies was 50% and 0% for the Control and Drainage groups, respectively (p < .001). Draining did not affect the pregnancy rate. These results indicate that puncture and drainage of the subordinate follicles at insemination may eliminate the risk of twin pregnancies and reduce the risk of subsequent pregnancy loss by increasing the incidence of additional corpora lutea.     

Annealing c60+: synthesis of fullerenes and large carbon rings

Laser vaporization of graphite generates C(60)(+) cluster ions that are fullerenes and a mixture of roughly planar polycyclic polyyne ring isomers. Experimental studies of the annealing of the non-fullerene C(60)(+) ions indicate that they can be converted (in the gas phase) into the fullerene and an isomer that appears to be a large monocyclic ring. Some fragmentation is associated with conversion to the fullerene geometry, but the majority of the non-fullerene C(60)(+) isomers are cleanly converted into an intact fullerene. The emergence of the monocyclic ring (as the clusters are annealed) suggests that this is a relatively stable non-spheroidal form of these all carbon molecules. The estimated activation energies for the observed structural interconversions are relatively low, suggesting that these processes may play an important role in the synthesis of spheroidal fullerenes.     

The Encyclopaedia of Arthropod-transmitted Infections of Man and Domesticated Animals. Edited by M.W. Service

Tropical Animal Health and Production -     

Perchlorate is Not a Common Contaminant of Fertilizers

Perchlorate consumption can cause mental retardation and tumour formation in humans. Recent suggestions that perchlorate may be present as a contaminant in fertilizers and fertilizer components have caused concern in the fertilizer industry. The present study developed methods for improving the HPLC analysis of perchlorate and used these methods to survey 15 US fertilizers for perchlorate. Extraction with 50 m M NaOH rather than water was found to improve extraction efficiency from 84 to 98%. The incorporation of Ca(HO)₂ into the extraction medium to yield 1 : 0.5 or 1 : 1, SO₄^– : Ca⁺² molar ratios reduced the analytical interference caused by SO₄^–2 by reducing the slope of the SO₄^–2 peak tail by ∼75%. The study found no perchlorate in any of the fertilizers investigated.     

Creatinine and pseudouridine in plasma and urine from Brahman-cross steers fed a low, medium or high plane of nutrition

Metabolic state as influenced by growth rate may influence meat toughness and can be estimated from metabolites excreted in urine. Urine collection over 24 h requires animals to be constrained in metabolism crates for many days. Single blood sampling to estimate metabolites in plasma would be less stressful on animals than collecting 24 h urine excretion. This study investigated the hypothesis that the plasma concentrations of pseudouridine and creatinine were representative of those found in 24 h urine excretions in steers fed different quality diets. Eleven Brahman-cross steers were fed a high (n = 3), medium (n = 4) or low (n = 4) quality hay diet for three weeks. Steers were catheterized and housed in metabolism crates for 6 days. Urine was collected every 24 h and total volume sub-sampled for analyses of creatinine and pseudouridine. Jugular blood was collected from each steer every 3 h from 07:30 to 16:30 h. Plasma was separated from red blood cells by centrifugation and frozen for creatinine and pseudouridine analyses. No time of day effect was apparent for pseudouridine or creatinine so daily means were used to test for effect of diet and to relate to urinary concentrations. Nutritional restriction halted live weight gain but had no effect on urinary or plasma pseudouridine, suggesting that diet did not affect tRNA turnover. Increased plasma creatinine concentrations and reduced urinary creatinine concentration in steers experiencing nutritional restriction indicated that their renal clearance rate decreased. As a result, the ratio of plasma pseudouridine to creatinine concentration was not directly proportional to that of 24 h urinary excretion.     

The use of computed tomography to diagnose bilateral forelimb tendon pathology in a horse with unilateral lameness

A horse with unilateral forefoot lameness had bilateral deep digital flexor tendon (DDFT) lesions on computed tomography (CT). Venous contrast enhanced CT revealed distal sesamoidean impar desmitis in the lame forelimb. Computed tomography is useful for diagnosis of soft tissue lesions within the hoof capsule and contrast enhancement improves lesion conspicuity.     

Tillage and crop residue management affect vertisol properties and grain sorghum growth over seven years in the semi-arid sub-tropics. 1. Crop residue and soil water during fallow periods

The effects of fallow surface management treatments on stubble (crop residue) levels and soil water storage were studied during seven fallow periods between grain sorghum crops on a grey Vertisol near Biloela in central Queensland, Australia. Treatments were disc (D), blade (B) and zero (Z) tillage, each with stubble or residue from preceding crops either retained (+) or removed (-) at the start of the fallow periods, which were of 7–8 months duration.

Where stubble was retained, stubble dry matter levels on the soil surface at the start of the fallow period were mainly influenced by stubble produced by the previous crop, but also by residual stubble on the soil surface before the previous crop. The general order was D +< B +< Z+.

Stubble dry matter and stubble cover on the soil surface declined during the fallow period in all stubble-retained treatments, with the greatest reductions occurring after the initial disc or blade tillage. From the start to end of the fallow, mean reductions in stubble dry matter and stubble cover were, respectively, 60 and 74% in D+, 31 and 57% in B+, and 17 and 24% in Z+. Mean stubble dry matter levels on the soil surface at the end of the fallow period in December–January were 1030, 2030 and 2910 kg ha⁻¹ in D+, B+ and Z+, respectively; corresponding stubble cover levels were 8, 16 and 35%.

Mean plant available water capacity to 1.8 m was 201 mm. Mean fallow soil water accumulation varied between fallow periods from 11 to 102 mm. The corresponding variation in mean fallow water storage efficiency (percentage of rainfall over the fallow stored in the soil) was from 3 to 37%. Fallow soil water accumulation was significantly (P<0.05) higher in Z+ (116 mm) than in Z- (86 mm), D+ (96 mm) and D- (84 mm) in one fallow period.

During the fallow period, B+ and Z+ generally resulted in higher plant available water than other treatments at mean values of 50–100 mm. However, these effects were not present at higher plant available water levels (mean of 128–164 mm), as occurred at the end of six fallow periods. The main treatment effect at the end of the fallow was for significantly (P<0.05) lower plant available water in Z-.