Key Factors Affecting Reproductive Success of Thoroughbred Mares and Stallions on a Commercial Stud Farm

To evaluate factors contributing to fertility of thoroughbred mares, data from 3743 oestrous periods of 2385 mares were collected on a large thoroughbred farm in Ireland. Fourteen stallions (mean age 8.3 years; range 4–15 years) had bred 2385 mares (mean age 9.4 years; range 3–24 years). Maiden mares accounted for 12%, mares with a foal at foot for 64%, and barren, slipped or rested mares for 24% of the total. The mean pregnancy rate per cycle was 67.8% (68.6% in year 1 and 66.9% in year 2). Backward stepwise multivariable logistic regression analysis was utilized to develop two models to evaluate mare factors, including mare age, reproductive status, month of foaling, dystocia, month of cover, foal heat, cycle number, treatments, walk‐in status and stallion factors including stallion identity, stallion age, shuttle status, time elapsed between covers and high stallion usage on the per cycle pregnancy rate and pregnancy loss. Old age (p < 0.001) and cover within 20 days post‐partum (p < 0.003) were associated with lowered pregnancy rates. High mare age (p < 0.05) and barren, slipped or rested reproductive status (p = 0.05) increased the likelihood of pregnancy loss. Uterine inflammation or infection, if appropriately treated, did not affect fertility. Only high usage of stallions (used more than 21 times in previous week) was associated with lowered (p = 0.009) pregnancy rates. However, shuttle stallions were more likely to have increased (p = 0.035) pregnancy survival, perhaps reflecting a bias in stallion selection. In conclusion, mare age exerted the greatest influence on fertility; nonetheless, thoroughbreds can be effectively managed to achieve high reproductive performance in a commercial setting.     

Are brown trout Salmo trutta fario and rainbow trout Oncorhynchus mykiss two of a kind? A comparative study of salmonids to temperature‐influenced Tetracapsuloides bryosalmonae infection

Proliferative kidney disease (PKD) of salmonids caused by Tetracapsuloides bryosalmonae causes high mortalities of wild brown trout (Salmo trutta fario) and farmed rainbow trout (Oncorhynchus mykiss) at elevated water temperatures. Here the aim was to compare the temperature‐dependent modulation of T. bryosalmonae in the two salmonid host species, which display different temperature optima. We used a novel experimental set‐up in which we exposed brown trout and rainbow trout to an identical quantified low concentration of T. bryosalmonae for a short time period (1 hr). We followed the development of the parasite in the fish hosts for 70 days. PKD prevalence and parasite kinetics were assessed using qPCR. Exposures were performed at temperatures (12°C and 15°C) that reflect an environmental scenario that may occur in the natural habitat of salmonids. T. bryosalmonae infection was confirmed earliest in brown trout kept at 15°C (day 7 post‐exposure) while, in all other groups, T. bryosalmonae was not confirmed until day 15 post‐exposure. Moreover, significantly greater infection prevalence and a faster increase of parasite intensity were observed in brown trout kept at 15°C than in all other groups. These results indicate that PKD is differentially modulated by water temperature in related host species.     

Measurement of aldosterone in feline, canine and human urine

BACKGROUND: Systemic hypertension is an important problem in older cats associated with kidney disease and hypokalaemia, suggesting that excessive activity of the renin-angiotensin-aldosterone system might contribute to the hypertensive state. Fluctuations in plasma renin activity and plasma aldosterone concentrations complicate the interpretation of these assays. OBJECTIVES: The aim of this study was to determine whether measurement of urinary aldosterone excretion in cats aided the investigation of hypertension. METHODS: Urine concentrations of free (ethyl acetate extract) and 18-glucuronidated aldosterone (acid hydrolysis before extraction) were measured by radioimmunoassay in normal, normotensive and hypertensive azotaemic cats (n=11 per group). Urine samples from 11 healthy human volunteers and eight normal dogs were also analysed for comparison. Urinary aldosterone concentration was corrected for the urinary creatinine concentration. RESULTS: Cats excreted 7.3 times less free aldosterone than human beings, and no free aldosterone was detected in dog urine. Acid hydrolysis led to large increases in aldosterone recovery from both human beings and dog but not feline urine. No significant effect of hypertension or azotaemia on feline urinary aldosterone concentration was found. CLINICAL SIGNIFICANCE: Measurement of aldosterone in feline urine using the available methodology has limited or no utility in investigating feline hypertension.     

Habitat quality,not habitat amount,drives mammalian habitat use in the Brazilian Pantanal

Landscape Ecology - An understanding of species-habitat relationships is required to assess the impacts of habitat fragmentation and degradation. To date, habitat modeling in fragmented landscapes...     

Investigation of the composition, turnover, and thermal properties of ruptured cranial cruciate ligaments of dogs

OBJECTIVE: To assess different components of the extracellular matrix with regard to their thermal properties, composition, and turnover in ruptured cranial cruciate ligaments (CCLs) of dogs, compared with components of intact CCLs from a breed predisposed to CCL failure. SAMPLE POPULATION: Ruptured CCLs obtained from 8 dogs of breeds predisposed to ruptured CCLs and intact CCLs from 12 cadaveric Labrador Retrievers. PROCEDURE: Ruptured and intact CCLs were analyzed for water content; collagen content and collagen cross-links were evaluated via hydroxyproline and amino-acid analyses, respectively. Glycosaminoglycan (GAG) content was analyzed via dimethylmethylene blue and uronic acid assays. Matrix metalloproteinases (MMPs)-2 and -9 and the tissue inhibitors of metalloproteinases (TIMPs)-1 and -2 were detected via gelatin SDS-PAGE zymography and reverse gelatin zymography. Thermal analysis of ligaments was performed by use of differential scanning calorimetry. RESULTS: Ruptured CCLs had significantly higher lamounts of immature cross-links, total and sulfated GAGs, and water content, compared with that of the intact ligaments. Compared with intact CCLs, concentration of pro-MMP-2 was significantly higher in ruptured CCLs; the maximum temperature of collagen denaturation was significantly lower in the ruptured CCLs. CONCLUSIONS AND CLINICAL RELEVANCE: The extracellular matrix of ruptured CCLs had an increased matrix turnover indicated by increased collagen and GAG synthesis, compared with that of intact CCLs. Although the extracellular matrix changes may have occurred before ligament rupture, it is possible that these observed changes may be part of a reparative process after rupture.     

Climate Change and North American Rangelands: Assessment of Mitigation and Adaptation Strategies

Recent climatic trends and climate model projections indicate that climate change will modify rangeland ecosystem functions and the services and livelihoods that they provision. Recent history has demonstrated that climatic variability has a strong influence on both ecological and social components of rangeland systems and that these systems possess substantial capacity to adapt to climatic variability. Specific objectives of this synthesis are to: 1) evaluate options to mitigate greenhouse gas emissions and future climate change; 2) survey actions that individuals, enterprises, and social organizations can use to adapt to climate change; and 3) assess options for system transformation when adaptation is no longer sufficient to contend with climate change. Mitigation for carbon sequestration does not appear economically viable, given the small and highly variable carbon dioxide fluxes of rangeland ecosystems and the high transaction costs that would be incurred. In contrast, adaptation strategies are numerous and provide a means to manage risks associated with climate change. Adaptation strategies are diverse, including altered risk perception by individuals, greater flexibility of production enterprises, and modifications to social organizations that emphasize climatic variability, rather than consistency. Many adaptations represent “no regrets” actions because their implementation can be justified without emphasis on pending climate change. Adaptations specific to livestock production systems can include flexible herd management, alternative livestock breeds or species, innovative pest management, modified enterprise structures, and geographic relocation. Social-ecological systems in which adaptation is insufficient to counter the adverse consequences of climate change might undergo transformative change to produce alternative ecosystem services, production enterprises, and livelihoods. The rangeland profession is in a pivotal position to provide leadership on this global challenge because it represents the intersection of management and scientific knowledge, includes diverse stakeholders who derive their livelihoods from rangelands, and interacts with organizations responsible for rangeland stewardship.