A.G.J. Velthuis

Invited review: Sensors to support health management on dairy farms

Since the 1980s, efforts have been made to develop sensors that measure a parameter from an individual cow. The development started with individual cow recognition and was followed by sensors that measure the electrical conductivity of milk and pedometers that measure activity. The aim of this review is to provide a structured overview of the published sensor systems for dairy health management. The development of sensor systems can be described by the following 4 levels: (I) techniques that measure something about the cow (e.g., activity); (II) interpretations that summarize changes in the sensor data (e.g., increase in activity) to produce information about the cows status (e.g., estrus); (III) integration of information where sensor information is supplemented with other information (e.g., economic information) to produce advice (e.g., whether to inseminate a cow or not); and (IV) the farmer makes a decision or the sensor system makes the decision autonomously (e.g., the inseminator is called). This review has structured a total of 126 publications describing 139 sensor systems and compared them based on the 4 levels. The publications were published in the Thomson Reuters (formerly ISI) Web of Science database from January 2002 until June 2012 or in the proceedings of 3 conferences on precision (dairy) farming in 2009, 2010, and 2011. Most studies concerned the detection of mastitis (25%), fertility (33%), and locomotion problems (30%), with fewer studies (16%) related to the detection of metabolic problems. Many studies presented sensor systems at levels I and II, but none did so at levels III and IV. Most of the work for mastitis (92%) and fertility (75%) is done at level II. For locomotion (53%) and metabolism (69%), more than half of the work is done at level I. The performance of sensor systems varies based on the choice of gold standards, algorithms, and test sizes (number of farms and cows). Studies on sensor systems for mastitis and estrus have shown that sensor systems are brought to a higher level; however, the need to improve detection performance still exists. Studies on sensor systems for locomotion problems have shown that the search continues for the most appropriate indicators, sensor techniques, and gold standards. Studies on metabolic problems show that it is still unclear which indicator reflects best the metabolic problems that should be detected. No systems with integrated decision support models have been found.

Financial consequences of the Dutch bluetongue serotype 8 epidemics of 2006 and 2007

This study calculates the financial consequences of the bluetongue serotype 8 (BTV8) epidemics of 2006 and 2007 in the Netherlands. We constructed a deterministic economic model that is compatible with the Dutch livestock production systems for cattle, sheep and goats. Two hundred cattle farms and 270 sheep farms were infected with BTV8 in the epidemic of 2006, whereas 30,417 cattle farms, 45,022 sheep farms and 35,278 goat farms were estimated to be infected in the epidemic of 2007. The net costs (costs minus benefits) of the BTV8 epidemic of 2006 (BT2006) was estimated at 32.4 million Euros. The net costs of the BTV8 epidemic of 2007 (BT2007) was valued at 164-175 million Euros, depending on the mortality and morbidity rates for cattle used. The losses account for 2%, 10% and 11% of the gross value of the primary production within Dutch pasture-based livestock farming that equals 1.6 billion Euros. Control measures accounted for 91% of the net costs of the BT2006, while diagnostic costs represented 7%. By contrast, for the BT2007 92% of the net costs were in the form of production losses and veterinary treatment fees, while only 6% were related to control measures. Furthermore, the control costs dropped from 29,630 in BT2006 to 10,990 in BT2007 mainly due to the costly indoor housing that was not obligatory during the BT2007 epidemic. The cattle sector suffered 88% and 85% of the net costs for the BT2006 and BT2007, respectively; the highest of all sectors.

Do farm audits improve milk quality

Milk quality is assessed using bulk milk analysis and by farm audits in the Netherlands. However, the extent of the effect that dairy farm audits have on milk quality is unknown. Data from over 13,000 audits performed on 12,855 dairy farms from February 2006 to April 2008 were merged with laboratory test results of 325,150 bulk milk samples collected 6 mo before and after the audit. A linear mixed model with the method of restricted maximum likelihood was conducted to study whether the total bacterial counts (TBC) of bulk milk were lower during the periods before and after the dairy farm audit. Results showed that TBC values were 2 to 6% lower (i.e., 0.010 to 0.026 log cfu/mL) for a period from 1.5 to at least 6 mo after an audit. Additionally, several variables were significantly associated with bulk milk TBC values: seasonality, total number of attention points (given if some checklist points were not appropriate), audit type, audit result, and the categories milking equipment maintenance, and utility room-tank maintenance. The TBC values increased with a higher level of attention points. Furthermore, the farms rejected based on the audit results had the highest average TBC values and the approved farms had the lowest values. If dairy farms had an overall negative audit assessment and consequently needed a re-audit in the following year, the TBC values of bulk milk were more likely to be higher. Auditing may provide dairy farmers the opportunity to receive advice about factors that influence bulk milk TBC values, for a period of at least 6 mo following the audit.

Design and analysis of an Actinobacillus pleuropneumoniae transmission experiment

This paper describes a methodology to quantify the transmission of Actinobacillus (A.) pleuropneumoniae from subclinically infected carrier pigs to susceptible contact pigs, and to test the effect of possible interventions on the transmission. The methodology includes the design of a transmission experiment, and a method with which A. pleuropneumoniae transmission can be quantified and with which the effect of an intervention on the transmission can be tested. The experimental design consists of two parts. First, subclinically infected carrier pigs are created by contact exposure of specific-pathogen-free pigs to endobronchially inoculated pigs. Second, transmission is observed from the group of carrier pigs to a second group of susceptible contact pigs after replacing the inoculated pigs by new contact pigs. The presented analytical method is a generalised linear model (GLM) with which the effect of an intervention on the susceptibility and infectivity can be tested separately, if the transmission is observed in heterogeneous populations. The concept of the experimental transmission model is illustrated by describing an A. pleuropneumoniae transmission experiment in which the effect of vaccination on the susceptibility is quantified. Although it could not be demonstrated that vaccination has an effect on the susceptibility of pigs, it was demonstrated that nasal excretion of A. pleuropneumoniae is related to the infectivity of pigs.

Towards an Integrated Approach in Supporting Microbiological Food Safety Decisions

Decisions on food safety involve consideration of a wide range of concerns including the public health impact of foodborne illness, the economic importance of the agricultural sector and the food industry, and the effectiveness and efficiency of interventions. To support such decisions, we propose an integrated scientific approach combining veterinary and medical epidemiology, risk assessment for the farm‐to‐fork food chain as well as agricultural and health economy. Scientific advice is relevant in all stages of the policy cycle: to assess the magnitude of the food safety problem, to define the priorities for action, to establish the causes for the problem, to choose between different control options, to define targets along the food chain and to measure success.

Costs of Rabies Control: An Economic Calculation Method Applied to Flores Island

Background Rabies is a zoonotic disease that, in most human cases, is fatal once clinical signs appear. The disease transmits to humans through an animal bite. Dogs are the main vector of rabies in humans on Flores Island, Indonesia, resulting in about 19 human deaths each year. Currently, rabies control measures on Flores Island include mass vaccination and culling of dogs, laboratory diagnostics of suspected rabid dogs, putting imported dogs in quarantine, and pre- and post-exposure treatment (PET) of humans. The objective of this study was to estimate the costs of the applied rabies control measures on Flores Island. Methodology/principal findings A deterministic economic model was developed to calculate the costs of the rabies control measures and their individual cost components from 2000 to 2011. The inputs for the economic model were obtained from (i) relevant literature, (ii) available data on Flores Island, and (iii) experts such as responsible policy makers and veterinarians involved in rabies control measures in the past. As a result, the total costs of rabies control measures were estimated to be US

A Systematic Scoping Study of the Socio-Economic Impact of Rift Valley Fever: Research Gaps and Needs

1.12 million (range: US

Financial Evaluation of Different Vaccination Strategies for Controlling the Bluetongue Virus Serotype 8 Epidemic in the Netherlands in 2008

0.60–1.47 million) per year. The costs of culling roaming dogs were the highest portion, about 39 percent of the total costs, followed by PET (35 percent), mass vaccination (24 percent), pre-exposure treatment (1.4 percent), and others (1.3 percent) (dog-bite investigation, diagnostic of suspected rabid dogs, trace-back investigation of human contact with rabid dogs, and quarantine of imported dogs). Conclusions/significance This study demonstrates that rabies has a large economic impact on the government and dog owners. Control of rabies by culling dogs is relatively costly for the dog owners in comparison with other measures. Providing PET for humans is an effective way to prevent rabies, but is costly for government and does not provide a permanent solution to rabies in the future.

Cost Analysis of Various Low Pathogenic Avian Influenza Surveillance Systems in the Dutch Egg Layer Sector

Rift Valley fever (RVF) is a severe mosquito‐borne disease affecting humans and domestic ruminants. RVF virus has been reported in most African countries, as well as in the Arabic Peninsula. This paper reviews the different types of socio‐economic impact induced by RVF disease and the attempts to evaluate them. Of the 52 papers selected for this review, 13 types of socio‐economic impact were identified according to the sector impacted, the level and temporal scale of the impact. RVF has a dramatic impact on producers and livestock industries, affecting public and animal health, food security and the livelihood of the pastoralist communities. RVF also has an impact on international trade and other agro‐industries. The risk of introducing RVF into disease‐free countries via the importation of an infected animal or mosquito is real, and the consequent restriction of access to export markets may induce dramatic economic consequences for national and local economies. Despite the important threat of RVF, few studies have been conducted to assess the socio‐economic impact of the disease. The 17 studies identified for quantitative analysis in this review relied only on partial cost analysis, with limited reference to mid‐ and long‐term impact, public health or risk mitigation measures. However, the estimated impacts were high (ranging from

Process audits versus product quality monitoring of bulk milk

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