Ten years of bovine virus diarrhoea virus (BVDV) control in Norway: a cost-benefit analysis.

A retrospective cost-benefit analysis was carried out on the Norwegian bovine virus diarrhoea (BVD) control and eradication strategy, for the years 1993-2003. Information regarding the control cost input parameters was gathered from the cattle industry (TINE Norwegian Dairies, GENO Breeding and AI association, and GILDE Norwegian Meat), The National Animal Health Authorities and The Veterinary Institute. We accounted for variable costs (both direct costs associated with the control, and those costs carried by the farmers as a consequence of the control program). The benefit was estimated as the difference between the assumed losses without control - represented overall as 10% increase of the observed 1993 BVD virus infection level - and the observed losses during the control period. An estimate of the financial losses associated with the BVD virus (BVDV) infection was based on studies of the herd level effects on health, reproduction, and production in dairy herds with evidence of recent BVDV infection. We used a stochastic simulation model to account for the total uncertainty in both the control cost and financial loss estimates. The annual net benefits over the 10 years of BVD control were discounted to a 1993 net present value (NPV). The median NPV of the BVD control, nationally, was estimated at 130 million NOK with a distribution of the NPV ranging from +51 to +201 million NOK (5th and 95th percentiles, respectively). Out of the total control costs the farmers and the farmer-owned industries (the co-operatives) had carried about 62% of these costs; however, the farmers were also the main beneficiaries. The Norwegian experience shows a robust cost-efficiency for a BVDV eradication strategy; this stands in sharp contrast to earlier studies where the results were not supportive. Even though every cattle population and country is unique, the Norwegian findings and experiences should have wider implications.

The Norwegian Healthier Goats programme--a financial cost-benefit analysis.

The aim of this study was to evaluate the profitability to dairy goat farmers of participating in the Healthier Goats disease control and eradication programme (HG), which was initiated in 2001 and is still running. HG includes the control and eradication of caprine arthritis encephalitis (CAE), caseous lymphadenitis (CLA) and paratuberculosis (Johne's disease) in Norwegian goat herds. The profitability of participation was estimated in a financial cost-benefit analysis (CBA) using partial budgeting to quantify the economic consequences of infectious disease control through HG versus taking no action. Historical data were collected from 24 enrolled dairy goat herds and 21 herds not enrolled in HG, and supplemented with information from a questionnaire distributed to the same farmers. Expert opinions were collected to arrive at the best possible estimates. For some input parameters there were uncertainty due to imperfect knowledge, thus these parameters were modelled as PERT probability distributions and a stochastic simulation model was built. The CBA model was used to generate distributions of net present value (NPV) of farmers' net cash flows for choosing to enroll versus not enrolling. This was done for three selected milk quota levels of 30000L, 50000L and 70000L, and both for before and after the introduction of a reduced milk price for the non-enrolled. The NPVs were calculated over time horizons of 5, 10 and 20 years using an inflation-adjusted discount rate of 2.8% per annum. The results show that participation in HG on average was profitable over a time horizon of 10 years or longer for quota levels of 50000L and 70000L, although not without risk of having a negative NPV. If farmers had to pay all the costs themselves, participation in HG would have been profitable only for a time horizon beyond 20 years. In 2012, a reduced milk price was introduced for farmers not enrolled in HG, changing the decision criteria for farmers, and thus, the CBA. When the analysis was altered to account for these changes, the expected NPV was positive over five years for the 50000L quota, indicating an increased profitability of enrolling in HG. The sensitivity analysis showed that particular attention should be paid to work load and investment costs when planning for disease control programmes in the future.

Applying fractal analysis to heart rate time series of sheep experiencing pain.

The objective assessment of pain is difficult in animals and humans alike. Detrended fluctuation analysis (DFA) is a method which extracts "hidden" information from heart rate time series, and may offer a novel way of assessing the subjective experience associated with pain. The aim of this study was to investigate whether any fractal differences could be detected in heart rate time series of sheep due to the infliction of ischaemic pain. Heart rate variability (HRV) was recorded continuously in five ewes during treatment sequences of baseline, intervention and post-intervention for up to 60 min. Heart rate time series were subjected to a DFA, and the median of the scaling coefficients (alpha) was found to be alpha=1.10 for the baseline sequences, 1.01 for the intervention sequences and 1.00 for the post-intervention sequences. The complexity in the regulation of heartbeats decreased between baseline and intervention (p approximately 0.03) and baseline and post-intervention (p approximately 0.01), indicating reperfusion pain and nociceptive sensitization in the post-intervention sequence. Random time series based on Gaussian white noise were generated, with similar mean and variance to the HRV sequences. No difference was found between these series (p approximately 0.28), pointing to a true difference in complexity in the original data. We found no difference in the scaling coefficient alpha between the different treatments, possibly due to the small sample size or a fear induced sympathetic arousal during test day 1 confounding the results. The decrease in the scaling coefficient alpha may be due to sympathetic activation and vagal withdrawal. DFA of heart rate time series may be a useful method to evaluate the progressive shift of cardiac regulation toward sympathetic activation and vagal withdrawal produced by pain or negative emotional responses such as fear.

Modelling sources of variation and risk factors for spinal deformity in farmed Atlantic salmon using hierarchical- and cross-classified multilevel models.

Sources of variation and risk factors for spinal deformity were investigated in a 2002-2004 year-class database of farmed Atlantic salmon using multilevel modelling. The prevalence of spinal deformity, recorded on subsamples of Atlantic salmon at individual days of harvest, was used as the outcome variable in the study. The dataset consisted of a multilevel structure with days of harvest (n=1441) nested within sea water pens (n=544), which were nested within sea water sites (n=39), which again were cross-classified with fresh water plants (n=21). A four level combined hierarchical- and cross-classified linear mixed model was built in MLwiN using Markov chain Monte Carlo (MCMC) estimation of variance components and fixed effects. Results revealed that a large part of the variance could be explained as sampling and classification random errors, accounting for 32% of the variation in the random intercept model and 41% of the variation in the final mixed effect model. Of the remaining "biological variation" in the random intercept model, 33% was explained by fixed effects where both the use half-year and 1.5 year old photo-manipulated autumn smolts (compared to using one year old spring smolt), and the use of six component vaccines (compared to using four and five component vaccines), were significantly associated with spinal deformity. The results suggest that the physiological changes at time of smoltification make Atlantic salmon susceptible to stressors causing vertebral deformation and that this is most evident in photo-manipulated fish smoltifying when temperature and growth is at its peak. The study further shows the potential of using multilevel modelling in epidemiological studies based on data from industrial aquaculture.

Exploring non-invasive methods to assess pain in sheep.

The aim of this study was to determine whether changes in eye temperature, measured using infrared thermography (IRT), and heart rate variability (HRV) can detect moderate levels of pain in sheep. Six ewes received the following treatments: 1) noxious ischaemic stimulus by application of a forelimb tourniquet (S), 2) noxious ischaemic stimulus and flunixin meglumine (S+F), and 3) flunixin meglumine (F). Maximum eye temperature, HRV, mechanical nociceptive threshold, blood pressure and behaviour were recorded for up to 60 min, including 15 min of baseline, 30 min during intervention and 15 min post-intervention. There was a tendency towards a decrease in the heart rate variability parameters RMSSD (the root mean square of successive R-R intervals) and SDNN (the standard deviation of all interbeat intervals) in treatment S compared to treatment F, and a significant increase in the same parameters between test day 1 and 3. A reduction in eye temperature was detected for all treatments during intervention, but no difference was found between S and F and S+N and F during intervention. The eye temperature decreased more in test day 2 and 3 compared to test day 1 during intervention. A significant reduction for both lip licking and vocalisation was observed between test day 1 and 3, and forward facing ears was the ear posture most frequently recorded in test day 1. We suggest that HRV is a sensitive, non-invasive method to assess mild to moderate pain in sheep, whereas IRT is a less sensitive method.