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Male Calves (male + calf)
Selected AbstractsA Novel Subcutaneous Counterpulsation Device: Acute Hemodynamic Efficacy During Pharmacologically Induced Hypertension, Hypotension, and Heart FailureARTIFICIAL ORGANS, Issue 7 2010Carlo R. Bartoli Abstract The miniaturization of mechanical assist devices and less invasive implantation techniques may lead to earlier intervention in patients with heart failure. As such, we evaluated the effectiveness of a novel, minimally invasive, implantable counterpulsation device (CPD) in augmenting cardiac function during impaired hemodynamics. We compared the efficacy of a 32-mL stroke volume CPD with a standard 40-mL intra-aortic balloon pump (IABP) over a range of clinically relevant pathophysiological conditions. Male calves were instrumented via thoracotomy, the CPD was anastomosed to the left carotid artery, and the IABP was positioned in the descending aorta. Hemodynamic conditions of hypertension, hypotension, and heart failure were pharmacologically simulated and data were recorded during CPD and IABP support (off, 1:2, 1:1 modes) for each condition. In all three pathophysiological conditions, the CPD and IABP produced similar and statistically significant (P < 0.05) increases in coronary artery blood flow normalized to the left ventricular (LV) workload. During hypotension and heart failure conditions, however, the CPD produced significantly greater reductions in LV workload and myocardial oxygen consumption as compared with the IABP. A novel 32-mL CPD connected to a peripheral artery produced equivalent or greater hemodynamic benefits than a standard 40-mL IABP during pharmacologically induced hypertension, hypotension, and heart failure conditions. [source] Escaping parasitism in the selfish herd: age, size and density-dependent warble fly infestation in reindeerOIKOS, Issue 3 2007Per Fauchald It has been suggested that animals may escape attack from mobile parasites by aggregating in selfish herds. A selfish herd disperses the risk of being attacked among its members and the per individual risk of parasite infection should therefore decrease with increasing animal density through the encounter,dilution effect. Moreover, in a selfish herd, dominant and agile animals should occupy the best positions and thereby receive fewer attacks compared to lower ranked animals at the periphery. We tested these predictions on reindeer (Rangifer tarandus tarandus) parasitized by warble flies (Hypoderma tarandi). Warble flies oviposit their eggs on reindeer during summer and induce strong anti-parasitic behavioural responses in the herds. In this period, reindeer are sexually segregated; females and calves form large and dense herds while males are more solitary. After hatching, the warble fly larvae migrate under the skin of their host where they encyst. In the present study encysted larvae were counted on newly slaughtered hides of male calves and 1.5 year old males from 18 different reindeer herds in Finnmark, northern Norway with large contrasts in reindeer density. In reindeer, body mass is correlated with fitness and social status and we hypothesized that individual carcass mass reflected the animal's ability to occupy the best positions within the herd. Larval abundance was higher among the 1.5 year old males than among the calves. For calves we found in accordance with the selfish herd hypothesis a negative relationship between larval abundance and animal density and between larval abundance and body mass. These relationships were absent for the 1.5 year old males. We suggest that these differences were due to different grouping behaviour where calves and females, but not males, aggregated in selfish herds where they escaped parasitism. [source] Dynamics of a protected black rhino (Diceros bicornis) population: Pilanesberg National Park, South AfricaANIMAL CONSERVATION, Issue 3 2005Halszka Hrabar Achieving maximum productivity in remnant populations of black rhinoceros is crucial to the persistence of this species. It was, therefore, investigated whether the black rhino population of Pilanesberg National Park had become regulated by resource limitation 22 years after introduction in 1979. Inter-calving intervals (which are not restricted to yearly time increments, due to asynchronous reproduction) decreased with an increase in rainfall, while the percentage of male calves born increased with increasing rainfall. The percentage of reproductive cows achieving maternal success increased with increasing density until 0.085 rhinos/km2, after which it decreased. This positive relationship at low densities is largely due to changes in the female age structure and the adult female/male ratio. The age at first calving tended to increase with increasing density, while mortality was not related to rainfall or density. It is concluded that the Pilanesberg black rhino population is showing the first signs of density dependence. It is proposed that black rhino conservators should monitor the percentage of cows achieving maternal success to detect early indications of density dependent resource limitation and use this as a criteria for decisions regarding metapopulation management. [source] Do EU direct payments to beef producers belong in the ,blue box'?AUSTRALIAN JOURNAL OF AGRICULTURAL & RESOURCE ECONOMICS, Issue 1 2003Seamus McErlean In the Uruguay Round Agreement on Agriculture, so-called ,blue box' support measures were exempted from reduction commitments, provided they were delivered under ,production-limiting' programs. Although classified as ,blue box', the EU system of direct payments (DP) to beef farmers imposes ,claim-limiting' restrictions rather than ,production-limiting' restrictions, allowing farmers to keep additional animals over and above the number upon which they are eligible to claim DP. The present paper provides empirical evidence that EU direct payments capitalise into the market prices of male calves and young steers in Ireland. It is also likely that DP capitalises into the prices of beef cows and heifers. Given this capitalisation process, some farmers can obtain ,capitalised' DP on animals produced over and above the ,claim-limiting' restrictions, by selling these animals through auction markets. Thus, ,capitalised' DP probably encourages production over and above the limiting measures. [source] | ||||||||||