Trends in cow numbers and culling rate in the Irish cattle population, 2003 to 2006

Cows are the main economic production units of Ireland's cattle industry. Therefore, demographic information, including overall numbers and survival rates, are relevant to the Irish agricultural industry. However, few data are available on the demographics of cows within a national population, either in Ireland or elsewhere, despite the recent development of comprehensive national cattle databases in many EU Member States. This study has sought: to determine the rate of cow culling from the national herd; to determine the rate of culling by type (dairy, beef), age, method of exit, date of exit and interval between last calving and exit; to calculate the national cow on-farm mortality rate; and to compare the Irish rates with published data from other countries. This work was conducted using data recorded in the national Cattle Movement Monitoring System (CMMS). Culling refers to the exit of cows from the national herd, as a result of death but regardless of reason, and cow-culling rate was calculated as the number of cow exits (as defined above) each year divided by the number of calf births in the same year. Culling rate was determined by type (dairy or beef), date of birth, method of exit (slaughter or on-farm death), month of exit and interval between last calving and exit. The average cow-culling rate during 2003 to 2006 was 19.6% (21.3% for dairy, 18% for beef). While comparisons must be treated with caution, it concluded that the overall rates of culling in Ireland fell within published internationally accepted norms. The on-farm mortality rate of 3.2-4.1% was similar to that reported in comparable studies

Physician-assisted suicide: a review of the literature concerning practical and clinical implications for UK doctors

BACKGROUND: A bill to legalize physician-assisted suicide in the UK recently made significant progress in the British House of Lords and will be reintroduced in the future. Until now there has been little discussion of the clinical implications of physician-assisted suicide for the UK. This paper describes problematical issues that became apparent from a review of the medical and psychiatric literature as to the potential effects of legalized physician-assisted suicide. DISCUSSION: Most deaths by physician-assisted suicide are likely to occur for the illness of cancer and in the elderly. GPs will deal with most requests for assisted suicide. The UK is likely to have proportionately more PAS deaths than Oregon due to the bill's wider application to individuals with more severe physical disabilities. Evidence from other countries has shown that coercion and unconscious motivations on the part of patients and doctors in the form of transference and countertransference contribute to the misapplication of physician-assisted suicide. Depression influences requests for hastened death in terminally ill patients, but is often under-recognized or dismissed by doctors, some of whom proceed with assisted death anyway. Psychiatric evaluations, though helpful, do not solve these problems. Safeguards that are incorporated into physician-assisted suicide criteria probably decrease but do not prevent its misapplication. SUMMARY: The UK is likely to face significant clinical problems arising from physician-assisted suicide if it is legalized. Terminally ill patients with mental illness, especially depression, are particularly vulnerable to the misapplication of physician-assisted suicide despite guidelines and safeguards

Suboptimal herd performance amplifies the spread of infectious disease in the cattle industry

Farms that purchase replacement breeding cattle are at increased risk of introducing many economically important diseases. The objectives of this analysis were to determine whether the total number of replacement breeding cattle purchased by individual farms could be reduced by improving herd performance and to quantify the effects of such reductions on the industry-level transmission dynamics of infectious cattle diseases. Detailed information on the performance and contact patterns of British cattle herds was extracted from the national cattle movement database as a case example. Approximately 69% of beef herds and 59% of dairy herds with an average of at least 20 recorded calvings per year purchased at least one replacement breeding animal. Results from zero-inflated negative binomial regression models revealed that herds with high average ages at first calving, prolonged calving intervals, abnormally high or low culling rates, and high calf mortality rates were generally more likely to be open herds and to purchase greater numbers of replacement breeding cattle. If all herds achieved the same level of performance as the top 20% of herds, the total number of replacement beef and dairy cattle purchased could be reduced by an estimated 34% and 51%, respectively. Although these purchases accounted for only 13% of between-herd contacts in the industry trade network, they were found to have a disproportionately strong influence on disease transmission dynamics. These findings suggest that targeting extension services at herds with suboptimal performance may be an effective strategy for controlling endemic cattle diseases while simultaneously improving industry productivity

Extended models of the ventilatory response to sustained isocapnic hypoxia in humans.

The purpose of this study was to examine extensions of a model of hypoxic ventilatory decline (HVD) in humans. In the original model (model I) devised by R. Painter, S. Khamnei, and P. Robbins (J. Appl. Physiol. 74: 2007-2015, 1993), HVD is modeled entirely by a modulation of peripheral chemoreflex sensitivity. In the first extension (model II), a more complicated dynamic is used for the change in peripheral chemoreflex sensitivity. In the second extension (model III), HVD is modeled as a combination of both the mechanisms of Painter et al. and a component that is independent of peripheral chemoreflex sensitivity. In all cases, a parallel noise structure was incorporated to describe the stochastic properties of the ventilatory behavior to remove the correlation of the residuals. Data came from six subjects from a study by D.A. Bascom, J.J Pandit, I.D. Clement, and P.A. Robbins (Respir. Physiol. 88: 299-312, 1992). For model II, there was a significant improvement in fit for two out of six subjects. The reasons for this were not entirely clear. For model III, the fit was again significantly improved in two subjects, but in this case the subjects were those who had the most marked undershoot and recovery of ventilation at the relief of hypoxia. In these two subjects, the chemoreflex-independent component contributed approximately 50% to total HVD. In the other four subjects, the chemoreflex-independent component contributed approximately 10% to total HVD. It is concluded that in some subjects, but not in others, there may be a component of HVD that is independent of peripheral chemoreflex sensitivity

Changes in peripheral chemoreflex sensitivity during sustained, isocapnic hypoxia.

One hypothesis concerning the origin of hypoxic ventilatory decline is that hypoxia acts centrally to depress peripheral chemoreflex loop activity. To investigate possible changes in peripheral chemoreflex loop activity during sustained, isocapnic hypoxia, the ventilatory responses to four one minute pulses of either extra hypoxia (45 Torr) or carbon dioxide (8 Torr above resting levels) were measured in man at minutes 2, 7, 12, and 17 of a 23 min isocapnic, hypoxic period (50 Torr). For hypoxia, the first pulse response (130%) was significantly greater (P less than 0.05) than the fourth response (74%). For CO2, pulse responses 2 and 3 (101 and 103%, respectively) were significantly greater (P less than 0.05) than the fourth response (91%). A central depression of peripheral chemoreflex loop activity should affect peripheral sensitivities to CO2 and hypoxia equally. Our results suggest that the peripheral sensitivity to hypoxia declined more than that to CO2, implying a peripheral chemoreceptor origin for hypoxic ventilatory decline

Effects of dopamine and domperidone on ventilation during isocapnic hypoxia in humans.

In order to investigate the role of dopamine in the ventilatory response to sustained, isocapnic hypoxia six subjects were studied three times in each of three pharmacological conditions: (1) in the absence of any drug administration, (2) during i.v. infusion of dopamine (3 micrograms.kg-1.min-1), and (3) after pretreatment with domperidone. Otherwise the experimental protocol was identical on each day and consisted of holding the subjects' end-tidal PO2 at 100 Torr for 10 min, then 50 Torr for 20 min and finally at 100 Torr again for 5 min. End-tidal PCO2 was held constant 2-3 Torr above normal throughout the experiment. Domperidone increased, and dopamine decreased the magnitudes of both the fast on- and off-responses, but neither drug affected the magnitude of the hypoxic ventilatory decline (HVD). The results of this study suggests: (1) that a peripheral dopaminergic mechanism is not involved in the genesis of HVD, and (2) the peripheral chemoreflex may be modulated peripherally to produce HVD

Effects of different levels of end-tidal PO2 on ventilation during isocapnia in humans.

The purpose of this investigation was to examine how the ventilatory decline observed during sustained, eucapnic hypoxia (HVD) is affected by different levels of hypoxia. Six subjects were each studied 3-6 times at each of 5 different levels of isocapnic hypoxia (end-tidal PO2 equal to 45, 50, 55, 65 and 75 Torr) in random order. The following variables were linearly related to saturation: (1) the rapid increase in ventilation at the onset of hypoxia; (2) the decline in ventilation over the period of hypoxia; and (3) the undershoot in ventilation below the pre-hypoxic control values at the relief of hypoxia. The rapid decrease in ventilation at the relief of hypoxia, however, was not linearly related to saturation. The mean time to peak ventilation was 2.13 +/- 0.07 min (+/- SE) at the onset of hypoxia, which was significantly longer (P less than 0.05) than the time to minimum ventilation at the relief of hypoxia of 1.23 +/- 0.18 min. The recovery from the undershoot in ventilation was 95% +/- 3% complete after 5 min, whereas the recovery in sensitivity to hypoxia was only 35% +/- 13% complete after 5 min of euoxia

A finite element modelling methodology for the non-linear stiffness evaluation of adhesively bonded single lap-joints. Part 1, Evaluation of key parameters

Reported in this paper is the development and verification of a finite element model with the fewest solid elements that can predict the non-linear stiffness characteristics of adhesively bonded single lap-joints in vehicle bodies. This work was driven by the need to significantly reduce computing hardware resources and run times for whole body analyses, and to achieve this goal the lap-joint needs to be modelled by a ‘small’ number of shell elements. It is well-known that the deformation of bonded lap-joints is dependent on seven key parameters, and that it is impractical to have a comprehensive characterisation of these by physical testing alone. To gain further understanding of the influence of these parameters on joint stiffness, over a wider range of variables than could be practically achieved in the laboratory, the ANSYS finite element code is used to simulate the highly non-linear (geometric and material) response of bonded joints. The authors use the laboratory results for joint stiffness from nineteen batches of laboratory specimens to aid the development, and verification, of numerical derived stiffness curves from a solid element model. Initially, a very refined mesh is used. This model is developed to have a ‘coarse’ solid element mesh that minimises run times without the calculated joint stiffness deviating by more than 10% from the batch mean of 10 measurements from laboratory testing. Numerical results from many simulations using the ‘coarse’ solid mesh model are used to show that, for the shell modelling methodology (reported in Part 2 on this work) to be successful, a representative model must account for the four key parameters of: adherend stress–strain relationship, adherend thickness, bond line thickness, and the over lap length. The ANSYS results also confirm that stiffness is directly proportional to joint width