Biomedical subjects

R B Huirne

Publications and source records attributed to R B Huirne.

At least 19 recordsLinked to original sources

PubMed2001

Improving nutrient efficiency as a strategy to reduce nutrient surpluses on dairy farms.

Dutch nutrient policy aims at reducing leaching of agricultural nutrients by internalizing the negative externalities associated with inefficient nutrient use. This is done by taxation of nitrogen and phosphate surpluses that exceed a hectare-based threshold of maximum-allowed surpluses. One management strategy farmers may use to reduce the nutrient surpluses on their farms is to improve the nutrient efficiency of the agricultural production process. This study employs Data Envelopment Analysis (DEA) to calculate nitrogen and phosphate efficiencies and an overall nutrient efficiency measure for a 3-year panel of 114 Dutch dairy farms. Subsequent analyses show the impact of both farm intensity and nutrient efficiency on the nitrogen and phosphate surpluses. It appears that farm intensity has a positive effect on efficiency, but efficiency and intensity exert opposite influences on nutrient surpluses. This is especially the case for nitrogen. The magnitude of a possible reduction of nitrogen surpluses through a strategy of efficiency improvement is therefore limited by the intensity of the farming system, unless the technology with which nutrients are used by the farming system can be further improved or input/output ratios will be altered.

Animal Husbandry↗

PubMed2001

An economic model to calculate farm-specific losses due to bovine respiratory disease in dairy heifers.

This paper describes a personal-computer-based model estimating the economic losses associated with clinical bovine respiratory disease in replacement heifers raised on individual dairy farms. The model is based on the partial-budgeting technique, and calculates the losses for two types of the disease separately: calf pneumonia and a seasonal outbreak. Model input includes farm-specific data such as the incidence of bovine respiratory disease, prices, and effects of the disease on the heifers' productivity. The input database was linked directly with the economic model. For all input parameters, default values used are available to the user and can be modified easily. Losses considered by the model include treatment expenditures and costs associated with increased mortality, increased premature culling, reduced growth, reduced fertility and reduced milk production in first lactation. Uncertainty is taken into account for parameters related to disease incidence, mortality and culling.Basic calculations for a typical Dutch dairy farm with 60% of the heifers (<3 months) affected, indicated total annual losses due to pneumonia average 31.2 per heifer present on the farm (range 18.4-57.1). The estimated losses for one seasonal outbreak with heifers up to 15-months old affected were 27.0 per heifer present (range 17.2-43.1). For both BRD types, the model's outcome was most sensitive to the number of heifers affected. Most of the parameters that had a major impact on the total losses were related to treatment or to the effects on the heifers' productivity. The model is user-friendly and flexible, and can be used as an interactive tool by farmers and veterinarians in the (economic) decision-making process regarding on-farm prevention and control of bovine respiratory disease.

Animals↗

PubMed2001

Stochastic simulation of catastrophic hail and windstorm indemnities in the Dutch greenhouse sector.

A risk analysis was performed to examine the effect of changes in the Dutch greenhouse sector on the probability of occurrence and magnitude of indemnities induced by catastrophic natural hazards. Analyzed historical indemnities, which included direct and consequential losses resulting from severe hail and windstorms, were used as input in a stochastic simulation model. Applications of the stochastic simulation model were illustrated under alternative risk conditions. A comparison was made between the current structure of greenhouse production and the expected structure in the next decade that differs with respect to the spatial distribution and average size.

Agriculture↗

PubMed2000

Dairy-heifer management in the Netherlands.

The objective of this study was to describe the Dutch rearing performance of dairy heifers by the evaluation of performance indices at weaning, breeding and calving. The second objective was to determine the extent to which dairy farmers use pre-set rearing targets and data monitoring for the evaluation of their rearing results. A questionnaire was sent to 3000 randomly chosen dairy cattle farmers to survey their heifer-rearing practices. Almost a third of the farmers (n=959) completed and returned the questionnaire. Of the farms responding, 29% realised an age at first calving of < or =24 months, 51% from 25 to 27 months, and 20% of > or =27 months. The farmers indicated that the average body weight after calving was within the range 525-550 kg. Average wither height class was 141-145 cm. Most farmers estimated the body-condition score of their heifers at calving to be 3-3.5. In 29% of the cases, weaning occurred at an age of < or =8 weeks, 35% at 9-10 weeks of age and 36% at > or =11 weeks of age. Most farmers (81%) commenced breeding at an age of > or =15 months. Intermediate evaluation of the rearing policy by means of performance goals and measurements was limited, and many of the reported performance indices on age and body weight were outside the range of the recommended target values. These results indicated that the common Dutch heifer-rearing management system could be improved considerably.

Animal Husbandry↗

PubMed2000

Optimization of dairy heifer management decisions based on production conditions of Pennsylvania.

We used a dynamic programming model to determine optimum rearing decisions of dairy replacements. Heifers were described in the model by age, season, body weight, pregnancy state, and prepubertal growth rate. Prices and parameters were chosen to represent the dairy population of Pennsylvania. We calculated monthly costs and revenues from calf value, feed costs, veterinary costs, semen costs, carcass value, and full-grown heifer value. The model considered a stochastic variation in the onset of puberty, conception, involuntary disposal, and a seasonal variation in the prices of calves, heifers, and feed. Based on a critical prepubertal average daily gain of 0.9 kg/d and a maximum achievable postpubertal growth rate of 1.1 kg/d, the optimum practice resulted in an average age at first calving of 20.5 mo at a body weight of 563 kg. Discounted net returns equaled $107 per heifer per year. The optimum rearing practice was not sensitive to seasonal variation in prices. Nevertheless, the economic results per season of birth varied considerably; the highest income per heifer was obtained from heifers born in December ($142/yr), whereas those born in May yielded the lowest ($100/yr). Sensitivity analyses demonstrated a considerable influence of growth rate restrictions and variation in reproductive performance on both the optimal rearing practices as the expected net returns.

Animal Feed↗

PubMed1999

A model to estimate the financial consequences of classical swine fever outbreaks: principles and outcomes.

A model is presented aimed at a financial analysis of a Classical Swine Fever outbreak. Financial consequences are calculated for affected parties, including governments (EU and national), farms, and related industries in the production chain. The model can be used to calculate the losses of a real outbreak as well as of a simulated one. In this article, the model is applied to the 1997/1998 outbreak of Classical Swine Fever in the Netherlands. Results show that total financial consequences of the outbreak are US $2.3 billion. Consequential losses for farmers and related industries are US $423 million and US $596 million respectively. Budgetary consequences for governments include less than 50% of the total losses calculated by the model. The model can be adapted easily to suit other diseases and countries.

Animal Husbandry↗

PubMed1999

Monte Carlo simulation of virus introduction into the Netherlands.

In order to improve the understanding of the risk of introducing classical swine fever (CSF) and foot-and-mouth disease (FMD) into the Netherlands, a Monte Carlo simulation model was developed. The model, VIRiS (Virus Introduction Risk Simulation model) describes virus introduction into the Netherlands from outbreaks in other European countries. VIRiS is aimed at supporting decision makers involved in disease prevention. The model is based on historical and experimental data, supplemented with expert judgement, and provides the expected number, location and cause of primary outbreaks in the Netherlands. The paper gives a detailed description of the design and behaviour of VIRiS. The default outcomes of VIRiS show that in the current situation, the western and northern regions of the Netherlands are most prone to outbreaks of CSF and FMD. Most outbreaks originate from the countries neighbouring the Netherlands and the countries of southern Europe. Several alternative prevention strategies were evaluated using a combination of the VIRiS model and models describing the spread and economic consequences of outbreaks. A considerable financial window is available for measures aimed at speeding up the detection of epidemics in countries from which a Dutch outbreak may originate. Complete elimination of the risk associated with the risk factor 'returning trucks' reduces the annual losses due to FMD and CSF epidemics by approximately US$ 9 million. The approach is general and could also be applied to other diseases and countries.

Animal Husbandry↗

PubMed1999

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↗

PubMed1998

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↗

PubMed1998

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↗

PubMed1998

[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↗

PubMed1998

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↗

PubMed1998

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↗

PubMed1998

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↗

PubMed1997

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↗

PubMed1997

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↗

PubMed1997

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↗

PubMed1996

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↗