Response of vegetation and birds to severe wind disturbance and salvage logging in a southern boreal forest

Vegetation and birds were inventoried on the same plot before and after a severe windstorm in 1999 disturbed a mature black spruce (Picea mariana)–jack pine (Pinus banksiana) forest in northern Minnesota. Following the storm, another plot was established in an adjacent portion of the forest that was salvage-logged. Birds were inventoried on both plots through 2002. The original unsalvaged plot was prescribed-burned in 2004, but vegetation was surveyed through 2003, and through 2005 on the salvaged plot. We examined the effects of wind disturbance by comparing the pre-storm bird and vegetation communities with those developing afterwards through 2002 and 2003, respectively, and the effects of salvage logging by comparing vegetation and the bird community on the unsalvaged plot with those in the salvaged area. Wind reduced the canopy of the forest by over 90% with a temporary increase in the shrub layer, mostly resulting from tip-ups. Several plant species, including jack pine and beaked hazel (Corylus americana), appeared temporarily in the ground layer (<1 m height), but did not persist through 2003. Quaking aspen (Populus tremuloides) root sprouts were abundant in 2001, but decreased dramatically by 2003. Delayed mortality of tipped trees resulted in reduction of the shrub layer to pre-storm levels, and release of advanced regeneration black spruce and balsam fir (Abies balsamea). Bird species using the forest changed from dominance by canopy-foraging species to ground-brush foraging species, with an overall increase in bird diversity. Salvage logging resulted in significant reduction in coarse woody debris, and successful recruitment of jack pine seedlings. Quaking aspen sprouts were nearly 30 times more abundant in the salvage-logged area compared to the unsalvaged control. Ruderal species, especially red raspberry (Rubus ideaus), fringed bindweed (Polygonum cilinode), and several sedges (Carex spp.), were significantly more abundant after salvage logging. The bird community, on the other hand, was greatly diminished by salvage logging, with a reduction in diversity, density, and overall richness of species.     

Black soil blindness: A new mycotoxicosis of cattle grazing Corallocytostroma-infected Mitchell grass (Astrebla spp)

A new, fatal mycotoxicosis of cattle has been recognised in north-western Australia. A feeding trial confirmed the toxicity of a previously unknown species of Corallocytostroma that grows on Mitchell grass (Astrebla spp). The disease has been colloquially named ‘black soil blindness’ because its most prominent features are its confinement to pastures on black soil, and blindness and death of affected animals. Over 500 cattle have died and considerable subclinical disease is present. Above average wet season rainfall and extended growing seasons may explain the emergence of the fungus. The disease is important because cattle production in large areas of Australia utilise Mitchell grass pastures.     

Immunity and mastitis. Some new ideas for an old disease.

The biggest challenge for host immune defense against mastitis-causing bacteria in dairy cows is to quickly recruit large enough numbers of opsonizing molecules and mature neutrophils into milk such that intramammary pathogens are cleared before they multiply significantly and the inflammatory response gets out of control. Currently, this challenge is best facilitated when established mastitis control procedures are practiced on the farm, including proper hygiene, milking procedures, and regular administration of approved mastitis vaccines. However, mastitis is still a significant problem. New animal functional genomics research is beginning to allow scientists to solve the puzzle of mastitis susceptibility. Results of this type of research offer the hope of giant leaps toward a clear identification of molecular genetic variation and potential gene targets for therapies and immune manipulations that could significantly reduce the risk of clinical mastitis in traditionally susceptible cows.     

Evaluation of an automated colorimetric assay for the measurement of lipase activity in canine sera.

An automated colorimetric method for determining lipase activity in canine sera was evaluated for precision, linearity and correlation to existing assay methods. The colorimetric method was a commercial reagent that used a series of enzymatic reactions based on the hydrolysis of 1,2 diglyceride by pancreatic lipase. Within-run and between-run coefficients of variation were < 6.8% and < 8.3%, respectively. Linearity was determined to be at least 1366 U/L. Canine serum lipase concentrations attained using the colorimetric method were compared to both titrimetric and dry-film methods for measuring serum lipase activity, resulting in significant (P < or = 0.05) correlation coefficients of 0.92 and 0.77, respectively. Canine serum lipase concentrations measured using the colorimetric assay on 2 different automated analyzers had a significant (P < or = 0.05) correlation coefficient of 0.92. A laboratory reference range using serum samples from 56 healthy dogs (0-561 U/L) was established. There were no significant (P < or = 0.05) differences in mean serum lipase concentrations comparing male and female dogs or comparing young dogs (< or = 3 y) to mature (4-7 y) and older (> 7 y) dogs using this assay. It was concluded that the automated colorimetric assay was a reliable indicator of canine serum lipase activity and offered several advantages, including small sample volume and short analysis time.     

Review of the technique and complications of median J sternotomy in the dog and cat

The surgical and medical records of 67 dogs and nine cats which underwent median sternotomy over a five-year period were reviewed. The indication for median sternotomy and the short and longer term complications were recorded. Twenty-six of the dogs died or were euthanased within 48 hours of the surgery as a consequence of the pre-existing disease or complications of the intrathoracic surgical procedure. A further four dogs were enthanased between 48 hours and 14 days following confirmation of neoplastic processes. Thirty-seven dogs were alive at 14 days; of these, seven dogs (19 per cent) experienced short-term wound complications, including haemorrhage, wound infection, thoracic limb neurological deficits and excessive postoperative discomfort. Of the 37 dogs alive for longer term follow-up, eight dogs (22 per cent) experienced wound complications, including haemorrhage, sternal fracture, sternal osteomyelitis and delayed wound healing. No complications were noted in the cats.     

Magnesium supplementation of lactating ewes and lamb growth

Ewes rearing twin lambs on a restricted ration of irrigated pasture were either supplemented daily with 12.5 mg magnesium chloride or not. Serum magnesium levels measured 24 hours after the previous day's dose did not differ between treatments. They averaged 0.74 mmol/l during the period of supplementation with 36% of values below 0.7 mmol/l, the lower limit of the "normal" range. Milk consumption by and liveweight gains of lambs were not increased by magnesium supplementation indicating that ewe magnesium levels below 0.7 mmol/l serum did not limit production in this instance.