[The non-vaccination policy in economic perspective].
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Animals↗
Biomedical subjects
A A Dijkhuizen
Publications and source records attributed to A A Dijkhuizen.
Repeatability in ranking of dairy farms on technical and economic performance over years.
Repeatability of farm average 305-day milk production and gross margin per 100 kg of milk was evaluated for 39 farms. Ranking of gross margin, its underlying factors (i.e. milk price, returns from cull cows and calves, costs of concentrates, and costs of roughage purchases per 100 kg of milk), and 305-day milk production was not completely random over the four years of the study. The coefficient of concordance ranged between 0.55 and 0.82. The costs of roughage purchased had the lowest concordance over time, and 305-day milk production had the highest concordance. For each year and each farm, the difference between average gross margin and farm-specific gross margin was calculated. The standard deviations (SD) of these values was calculated for each farm, and showed differences between farms in variability in gross margin over years (the farm-year-specific SD varied between farms from 0.56 to 5.73). All the underlying factors showed a deviation over years. So, variability of gross margin can be due to changes in all underlying factors. The impact on gross margin of purchased roughage was not of major importance because its absolute impact on the gross margin is small. We concluded that milk-production data over one year is a reliable indicator for the typical farm milk production. Because gross margin fluctuates considerably over time, however it is preferred to base economic research on data from more than one year.
Animals↗
Adaptive conjoint analysis to determine perceived risk factors of farmers, veterinarians and AI technicians for introduction of BHV1 to dairy farms.
A study was carried out to determine the possibility of a more-closed farming system for (Dutch) dairy farms. The objective of the study was to provide effective and economically profitable management advice for improving the animal-health status of farms. Management measures will only be successfully applied if supported by farmers and their advisors (such as veterinarians). Therefore, the perception of farmers and advisors of the importance of various risk factors for the introduction of diseases to a farm was determined by using bovine herpes virus type 1 (BHV1) as an example. As part of the study, an evening-long workshop was organized and run thrice. In total, 49 farmers, veterinarians and AI technicians participated in these workshops. The computerized questionnaire technique was based on adaptive conjoint analysis (ACA). ACA has the advantage that participants can work with a large number of risk factors in a relatively short period of time. Another advantage of ACA (compared with standard questionnaires) is that the answers from each participant can be checked with regard to consistency with respect to the importance assigned to them. Data from participants with inconsistent responses can be excluded from further analyses. The results of the ACA interview were compared with the risk factors reported in the literature as being associated with BHV1 status (e.g. purchase of cattle, participation in cattle shows) and with farmers' actual management to prevent the introduction of diseases. The workshop participants were all operating in the dairy sector and they seemed well aware of the risk of direct animal contacts for the introduction of BHV1. Farmers thought visitors to be more risky than did AI technicians and (especially) veterinarians. Farmers who purchased cattle or participated in cattle shows were of the opinion that the risks of direct animal contacts were more important than did farmers who were not involved in those practices. Farmers whose farms were BHV1-positive (and participated in cattle shows more often) thought the risk of participation smaller than did farmers with BHV1-negative farms.
Animal Husbandry↗
Quantifying characteristics of information-technology applications based on expert knowledge for detection of oestrus and mastitis in dairy cows.
Expert opinions were elicited about the characteristics at the commercial-farm level of on-line information technology (IT) applications that are able to detect oestrus and mastitis in dairy cows. Since actual data of these characteristics are not available, judgmental data provided an alternative means to interpret the implications of research results for commercial farms. Applications included were activity measurement, milk-production measurement, electrical conductivity of quarter milk, automated concentrate feeders and milk-temperature measurement. Sensitivity and specificity of detection of oestrus (OD), clinical-mastitis (CMD) and subclinical-mastitis (SCMD) were ascertained. Conjoint-analysis was used to assess the effect of each application indirectly by decomposing the evaluated overall detection characteristics of a predefined number of IT combinations. The individual experts were consistent in evaluating the alternatives, but there was variation in estimates among experts. Estimations of the main effects of the applications and important first-order interactions were incorporated into the detection models. Implementation of all applications under study resulted in overall sensitivities and specificities of 82% and 90%, 73% and 87%, 58% and 82% for OD, CMD and SCMD, respectively. Further research is necessary that should take into account costs and benefits of the different detection systems based on the current status of farm performance (e.g. OD and mastitis incidence) and farm structure (e.g. farm size, years in operation of the milking parlour and parlour layout). Research to do this is currently in progress.
Animals↗
An epidemiological and economic simulation model to evaluate the spread and control of infectious bovine rhinotracheitis in The Netherlands.
Bovine herpesvirus type I (BHV1), causing infectious bovine rhinotracheitis (IBR), was introduced in the Netherlands in 1971. In 1993, about 42% of the dairy cows had antibodies against BHV1. In the future, stricter requirements are anticipated regarding the health status of exported breeding cows and material. To support policymakers in their decisions on IBR eradication, a simulation model was developed in which the epidemiological and economic consequences of various control strategies were evaluated. This paper describes the model and provides an overview of some important outcomes. In the model, dairy herds were classified into different disease states based on (1) the reproduction ratio of the disease (R, defined as the number of secondary cases caused by one infectious animal) (2) the within-herd prevalence, within each value of R and (3) the expected number of infectious animals in an infectious herd within each prevalence range. The dynamic transition probability of a herd going from one state to another per week depends on direct contacts between animals, and other contacts such as transmission through fomites, indirect transmission through other species, airborne transmission and minor disease-specific routes such as venereal or iatrogenic transmission. Five control strategies, including both a voluntary vaccination program and a compulsory vaccination program for all dairy herds were evaluated. A voluntary vaccination program with 50% participation is not expected to lead to eradication of IBR. It appears that compulsory vaccination would be necessary to reach an IBR-free status.
Animals↗
[BVD outbreak can be costly: a case report].
The losses caused by an BVD-outbreak on a Dutch dairy farm with approximately 100 dairy cows were determined. In this particular farm, calves which were born around the same time as a detected carrier calf were not sampled. These carrier calves were kept on as replacement heifers and caused additional loss on top of the losses already caused by the primary outbreak. The total economic loss was more than f 96.000,- or nearly f 1000,-per cow. This case report illustrates the potential for serious economic loss when an BVD free herd is reinfected combined with less adequate control measures.
Animals↗
[Introduction of BHV1 on dairy farms. Risk assessment by cattle farmers and veterinarians].
A study is being carried out at Wageningen Agricultural University together with, among others, the Animal Health Service to determine the possibilities and economic consequences of a more closed farming system for (Dutch) dairy farms. Three identical workshops, held in the evening, were organized as part of the study. The opinion of farmers and their veterinarians on the importance of risk factors for the introduction of diseases on a farm was determined, using Bovine Herpes Virus type 1 (BHV1) as an example. In total, 27 farmers and 13 veterinarians participated in the workshops and completed a computerized questionnaire that was based on Adapted Conjoint Analysis (ACA). The results of the farmers and veterinarians were compared. Both farmers and veterinarians seemed well aware of the risk of direct animal contacts for introduction of BHV1. Farmers thought visitors to be of more risk than veterinarians. By making use of information obtained from the ACA workshops, it will be possible to improve the advice given to different groups in the dairy sector.
Animals↗
Exploratory study on the economic value of a closed farming system on Dutch dairy farms.
A closed farming system may prevent the introduction of infectious diseases on to dairy farms and could be a good starting point for the eradication of these diseases. In order to introduce a closed farming system, farmers need to be made aware of how these diseases are introduced into the herd. Farmers will be more likely to implement a closed farming system when the economic value is quantified and attractive. An exploratory study was carried out to investigate the technical and economic results of closed dairy farms. Farms that purchased cattle and/or shared pasture (defined as 'open' farms) differed in technical results from farms that did not ('closed' farms). The results of the discriminant analysis showed that the 'closed' farms incurred lower costs for veterinary services, had a lower average age at first calving and a higher birth rate per 100 dairy cows. A linear regression analysis was carried out to investigate the influence of the farming system on economic performance. Being 'closed' was found to increase the net profit by 0.31 Pound per 100 kg of milk, or approximately 25 Pounds per cow per year or 5 per cent of the typical net return to labour and management (1 Pound = Dfl 2.80 in November 1996).
Animal Husbandry↗
Risk factors for existence of Bovine Herpes Virus 1 antibodies on nonvaccinating Dutch dairy farms.
A more closed farming system may prevent introduction of infectious diseases on dairy farms and can be a good starting point for control of these diseases. Data were available on the presence of Bovine Herpes Virus 1 (BHV1) antibodies in bulk milk and/or blood samples of Dutch dairy farms. Furthermore, information about the possible risk factors for introduction of infectious diseases was collected on 214 of these dairy farms. Data of 107 farms which had been never vaccinated against BHV1 remained for the analysis. A positive BHV1 status on these 107 farms could only be caused by introduction of BHV1. Risk factors for introduction of BHV1 on the farms were quantified using logistic regression. BHV1-positive farms purchased cattle and participated in cattle shows more often compared with BHV1-negative farms. A BHV1-positive farm also had more (professional) visitors in the barn who used farm clothing less often. The BHV1-positive farms were found to be situated closer to other cattle farms compared with the BHV1-negative farms.
Analysis of Variance↗
A descriptive study of visits by animal health specialists in pig farming: type, frequency, and herd-health management factors.
This research was carried out to analyse the visits specialists of the Dutch Animal Health Service made to growing and fattening pig farms. The type and frequency of the visits and identified herd-health management factors that did not meet accepted standards were investigated. In total 373 visit reports were studied. The majority of the visits (n = 306 of 373) were made to investigate the cause of health, welfare, and performance problems ('problem-solving visits'). Respiratory disorders were the main reason for requesting a specialist to assess farm conditions and management (n = 156). In the other 67 of 373 visit reports the specialists screened for herd-health management factors that did not meet standards for the prevention of disease ('screening visits'). For both types of visits, the main factors detected were abrupt changes in feeding regimens (e.g. changes in feed type, feed composition or feed supplier) (37%), inadequate measures to prevent introduction of pathogens by people and trucks (83%), and incorrect adjustment of the ventilation system (58-60%). The specialists focusing on housing-climate management, identified the majority of factors in an equal number irrespective of whether the visit was a problem-solving visit or a screening visit. This implies that even on farms that appear not to have health or performance problems, factors that relate to disease are present and may cause problems sooner or later. Although veterinary practitioners and other farm advisors assist farmers in their management to optimize herd health, the findings of the research suggest that advisors could provide additional support in situations where environmental and managerial factors play a role in pig health and performance. The knowledge of advisors about integrated herd-health management can be broadened by means of textbooks, courses, or computer programs.
Animal Husbandry↗
Effects of information technology on dairy farms in The Netherlands: an empirical analysis of milk production records.
This study empirically quantified the effects of the adoption of an automated concentrate feeder, on-line measurement of milk production, and activity measurement on milk production and reproduction. The data comprised annual results of Dutch farms operating in a milk quota system from 1987 to 1996; data included both adopters and nonadopters as well as farm results before and after adoption. The use of an automated concentrate feeder improved the annual carrier production of milk, milk protein, and milk fat (102, 4.95, and 5.52 kg per cow, respectively). In contrast, on-line measurement of milk production did not significantly affect milk production records. Calving interval was shortened by 5.7 d after the adoption of an activity measurement system but was not affected by the adoption of an automated concentrate feeder or by the measurement of on-line milk production.
Animal Feed↗
Economic evaluation of national identification and recording systems for pigs in Belgium.
Four national identification and recording (I&R) systems for the Belgian pig industry were evaluated economically, using a computer simulation model. These systems were: (1) the previous system; (2) a revised system (based on the previous one); (3) a system based on electronic identification; (4) a system similar to (3) but which also allows electronic monitoring of individual pigs. The evaluation of the systems particularly concerned their use in the control of classical swine fever (CSF). Four factors have shown to be very influential in economic decision making with respect to I&R systems: (1) the economic losses per CSF epidemic; (2) the frequency of CSF epidemics; (3) the operational costs of the I&R system; (4) the possibility of additional use of the system besides CSF control. It was concluded that for the Belgian situation, replacement of the previous I&R system by the revised one is economically justifiable. Because of high operational costs, electronic identification systems are only economically feasible in very specific situations, e.g. when a higher degree of additional use is possible or with a relatively high frequency of CSF epidemics.
Animal Husbandry↗
Estimating the rate of pseudorabies virus introduction into pig-finishing herds at regional level.
From February to June 1995, 5-12 blood samples were collected in each Dutch pig herd and tested for antibodies against pseudorabies virus (PRV). The percentage of PRV-seropositive pig-finishing herds in three regions with more than 1,000 pigs/km2 (regions 2, 4 and 7) was 6% (region 2), 12% (region 7), and 25% (region 4). The percentage of PRV-seropositive pig-finishing herds in five regions with fewer than 1,000 pigs/km2 (regions 1, 3, 5, 6, and 8) was 3% (region 1), 9% (region 3), 6% (region 5), 0% (region 6), and 4% (region 8). The small sample size allows only the detection of major outbreaks and the percentages of PRV-seropositive herds therefore under-estimate the actual virus circulation in the regions. The fraction of PRV introductions that will result in a major outbreak depends on the herd immunity and thus on the vaccination programme of the herds. By combining for each herd the occurrence or absence of a major outbreak with the herd immunity induced by the vaccination programme, we estimated the average rate at which PRV was introduced into finishing herds in the eight regions. The average number of PRV introductions per finishing herd per finishing period (16 weeks) in the pig-dense regions was estimated at 0.20 in region 2, 0.83 in region 4, and 0.48 in region 7. In the less densely populated regions this rate was estimated at 0.08 in region 1, 0.34 in region 3, 0.17 in region 5, 0.00 in region 6, and 0.09 in region 8. The eight regions could be classified into four areas with a statistically different (P < 0.05 in Mann Whithey U test) rate of PRV introduction: i) regions 1, 6, and 8; ii) regions 2 and 5; iii) regions 3 and 7; and iv) region 4.
Animals↗
Risks and economic consequences of introducing classical swine fever into The Netherlands by feeding swill to swine.
An effective animal disease prevention and eradication programme is of great importance for meat-exporting countries such as the Netherlands. If a serious outbreak of disease were to occur, the eradication measures required by the European Union and a possible ban on meat exports would have severe economic consequences. However, historical and experimental information on which these programmes can be based is scarce. Furthermore, until recently, an integrated approach which combined the various aspects of outbreaks and risks with economic consequences was lacking. This paper describes a project based on such an integrated approach. The project covered the elicitation of expert knowledge and the development of the virus introduction risk simulation model (VIRiS). VIRiS integrates objective and subjective information concerning risks and consequences of virus introduction, and thus presents policy-makers with a useful tool for the evaluation of existing prevention programmes and possible alternatives. VIRiS is illustrated for classical swine fever. A comparison is made between the current situation and a hypothetical situation where the risk factor 'swill feeding' is completely eliminated.
Animal Feed↗
Technical and economic models to support heifer management decisions: basic concepts.
To maximize herd profits, dairy farmers are faced with the complex dilemma of minimizing costs that are associated with rearing heifers while ensuring or enhancing lifetime economic productivity. Decisions about heifer management interact with underlying biological aspects of growth, thereby influencing future profitability. A thorough understanding of these biological interactions is lacking. Studies based on models could be useful in the evaluation of various rearing strategies. Currently available models for dairy cattle primarily focus on the dairy cow. In a dairy farm production system, management decisions concerning the rearing of livestock and the replacement of dairy cows strongly influence each other. In a model that describes the dairy herd as a multiple-component system, opportunity is greater to coordinate rearing and replacement policies. Expected benefits of such a model are discussed.
Animals↗
[I&R (identification and registration) system cattle: an analysis of its use during a foot-and-mouth-disease outbreak in The Netherlands].
The performance of the Dutch cattle I&R system was analysed, with emphasis on the potential use of the system for the control of an outbreak of foot and mouth disease (FMD). The analysis showed that not all mutations were centrally registered within the three working days that are allowed to pass between the actual change and the obligatory report. In particular, young calves and cattle heading for slaughter were reported too late. During an outbreak of FMD, the best strategy to trace animals off a farm seems to be first to identify all animals on the farm, using a preprocessed list of the animals that should be present on the farm according to the I&R system. Then all the animals that have left the farm during the last month can be traced in the central I&R computer or by asking the person to whom the farmer sold the cattle (the next owner). In the present study, 54% of the animals were localized within one day, and 94% within one week. Finally, some suggestions for improvement for the system are given.
Animal Husbandry↗
Basic framework for the economic evaluation of animal health control programmes.
The further integration of international markets means that co-ordinated policies against contagious animal infections have become increasingly important, and stricter demands for control and eradication should be expected in the future. To meet these demands, it would be desirable to create a computer simulation environment in which 'what if?' scenarios could be performed, in order to explore the epidemiological and economic effects of various infections and control strategies. The authors propose a flexible economic framework and illustrate this framework with an example. The framework has four elements: changes in the percentage of infectious herds, changes in product quantities, changes in product prices and economic integration. Each element is specifically defined and has its own input and output data, depending on the control strategy under consideration. In an illustration of the framework, probability distributions of the different control strategies are compared and the optimal strategy is chosen, according to the attitude of the decision-maker towards risk. Such a framework can be considered as a new standardised approach for comparing and selecting animal health control strategies, by integrating technical and economic data and principles.
Animal Diseases↗
[The financial consequences of tolerating or controlling IBR].
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Animal Husbandry↗