Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

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Farm-level risk factors for bovine mastitis in Dutch automatic milking dairy herds
Deng, Z. ; Koop, G. ; Lam, T.J.G.M. ; Lans, I.A. van der; Vernooij, J.C.M. ; Hogeveen, H. - \ 2019
Journal of Dairy Science 102 (2019)5. - ISSN 0022-0302 - p. 4522 - 4535.
automatic milking system - mastitis - nonlinear principal component analysis - principal component regression - risk factor

Automatic milking systems (AMS) are installed on a growing number of dairy farms worldwide. Management to support good udder health might be different on farms with an AMS compared with farms milking with a conventional milking system, as risk factors for mastitis on farms using an AMS may differ. The aim of this study was to identify farm level factors associated with mastitis on Dutch dairy farms using an AMS. In 2008, risk factor data were collected using a questionnaire combined with on-farm recordings of cow, stall, and AMS hygiene on 135 farms. These risk factor data were linked to 4 udder-health-associated dependent variables: average herd somatic cell count (HeSCCav), variance of the average herd somatic cell count (SCC) on test days (HeSCCvar), the average proportion of new high SCC cases (NHiSCC), and the farmer-reported annual incidence rate of clinical mastitis (IRCM). We employed regression models using multiple imputation to deal with missing values. Due to the high dimensionality of the risk factor data, we also performed nonlinear principal component analysis (NLPCA) and regressed the dependent variables on the principal components (PC). Good hygiene of cows and of AMS were found to be related to a lower HeSCCav and less NHiSCC. Effective postmilking teat disinfection was associated with a lower NHiSCC. A higher bulk tank milk SCC threshold for farmers' action was related to more NHiSCC. Larger farm size was related to lower HeSCCvar but higher NHiSCC. Negative attitude of farmers to animal health, higher frequency of checking AMS, and more time spent on viewing computer data were all positively related to higher IRCM. An NLPCA with 3 PC explained 16.3% of the variance in the risk factor variables. Only the first 2 PC were associated with mastitis. The first PC reflected older and larger farms with poor cow hygiene and AMS hygiene, and was related to higher HeSCCav and NHiSCC, whereas the second PC reflected newly built smaller farms with poor cow hygiene and low milk production, and was associated with higher HeSCCvar and NHiSCC, but lower IRCM. Our study suggests that many of the risk factors on conventional milking system farms are applicable to AMS farms, specifically concerning hygiene of the cows and the milking machine, but on large AMS farms, udder health may need more attention than on smaller AMS farms. Multiple imputation is instrumental to deal with missing values and NLPCA is a useful technique to process high dimensional data in our study.

Does clinical mastitis in the first 100 days of lactation 1 predict increased mastitis occurrence and shorter herd life in dairy cows?
Hertl, J.A. ; Schukken, Y.H. ; Tauer, L.W. ; Welcome, F.L. ; Gröhn, Y.T. - \ 2018
Journal of Dairy Science 101 (2018)3. - ISSN 0022-0302 - p. 2309 - 2323.
generalized linear mixed models - herd life - mastitis - survival analysis

The objectives of this study were to estimate the direct effects of clinical mastitis (CM) occurring in early productive life (defined as the first 100 d of the first lactation) of Holstein dairy cows on the future rate of CM occurrence and on the length of total productive lifetime. Information on CM cases and other data occurring in 55,144 lactations in 24,831 cows in 5 New York State Holstein herds was collected from January 2004 until February 2014. For the first objective, a generalized linear mixed model with a Poisson distribution was used to study the effects of CM cases occurring in the first 100 d of a cow's first lactation, as well as farm indicator and number of days in the cow's lifetime, on the future lifetime rate of CM. Only cows that had completed their productive life [i.e., all had been culled (or sold) or had died; n = 14,440 cows] were included in this analysis. For the second objective, a Cox proportional hazards model was used to study the effects of CM cases occurring in the first 100 d of a cow's first lactation on the length of total productive lifetime. The model was stratified by farm. All 24,831 cows were included in this analysis with right censoring. Cows experienced between 0 and 4 CM cases in the first 100 d of lactation 1. Over their lifetime, cows experienced between 0 and 25 CM cases. During the study period, 10% of all cows died and nearly half of all cows were culled. The average length of productive life, including censored observations, was 2.0 yr after first calving. Compared with cows having no CM cases in the first 100 d of lactation 1, cows with 1 CM case in that time period had a 1.5 times higher rate of total number of CM cases over their lifetime. Cows with 2 (or 3 or more) CM cases in the first 100 d of lactation 1 had a 1.7 times (or 2.6 times) higher rate of total number of CM cases over their lifetime. For each additional CM case occurring in the first 100 d of lactation 1, the hazard rate of culling increased by 34%. Given economic conditions for preferentially culling mastitic cows, the study findings may help farmers make optimal decisions with regard to culling of such cows.

Economic optimization of selective dry cow treatment
Scherpenzeel, C.G.M. ; Hogeveen, H. ; Maas, L. ; Lam, T.J.G.M. - \ 2018
Journal of Dairy Science 101 (2018)2. - ISSN 0022-0302 - p. 1530 - 1539.
antimicrobial reduction - dry cow treatment - economics - linear programming - mastitis
The objective of this study was to develop a mathematical model to identify a scenario with the lowest costs for mastitis associated with the dry period while restricting the percentage of cows to be dried off with dry cow antimicrobials. Costs of clinical and subclinical mastitis as well as antimicrobial use were quantified. Based on data from a large field trial, a linear programming model was built with the goal to minimize the costs associated with antimicrobial use at drying off. To enable calculations on minimizing costs of dry cow treatment on herd-level by drying-off decisions in an “average” herd, we created an example herd. Cows were projected on 3 different types of herds, based on bulk tank somatic cell count, and were categorized in groups based on parity and somatic cell count from the last test recording before drying-off. Economically optimal use of antimicrobials was determined while restricting the maximum percentage of cows dried off with antimicrobials from 100 to 0%. This restriction reveals the relationship between the maximum percentage of cows dried off with antibiotics and the economic consequences. A sensitivity analysis was performed to evaluate the effect of variation in the most important input variables, with the effect of dry cow antimicrobials resulting in a lower or higher percentage of clinical and subclinical mastitis depending on being dried off with or without dry cow antimicrobials, respectively, and the milk price. From an economic perspective, blanket dry cow treatment seems not to be the optimal approach of dry cow therapy, although differences between approaches were small. With lower bulk tank somatic cell counts, more dry cow antimicrobials can be omitted without economic consequences. The economic impact of reducing the percentage of clinical mastitis was found to be much larger than reducing the bulk tank somatic cell count. The optimal percentage of cows to be dried off with antimicrobials depends on the udder health situation, expressed as the bulk tank somatic cell count and the incidence of clinical mastitis. For all evaluated types of herds, selective dry cow treatment was economically more beneficial than blanket dry cow treatment. Economic profits of selective dry cow treatment are greater if bulk tank somatic cell count and clinical mastitis incidence are lower. Economics is not an argument against reduction of dry cow antimicrobials by applying selective dry cow treatment.
Intramammary immunization with ultraviolet-killed Escherichia coli shows partial protection against late gestation intramammary challenge with a homologous strain
Pomeroy, B. ; Gurjar, A. ; Sipka, A. ; Klaessig, S. ; Salmon, S. ; Quesnell, R. ; Schukken, Y.H. - \ 2016
Journal of Dairy Science 99 (2016)11. - ISSN 0022-0302 - p. 9014 - 9026.
Escherichia coli - late gestation - mastitis - vaccination

The objective of this study was to evaluate the efficacy of intramammary immunization with UV-killed Escherichia coli ECC-Z on prevention of intramammary colonization after a challenge with a dose of the homologous E. coli ECC-Z live bacteria. A total of 10 cows were included in a study to evaluate the efficacy of intramammary immunization. All 10 cows received an intramammary immunization of 100 cfu of UV-killed E. coli ECC-Z bacteria into one hind quarter at the time of dry off. Approximately 2 wk before the anticipated calving date, both hind quarters of all cows were challenged with 100 cfu of live E. coli ECC-Z bacteria. Five of the cows were vaccinated parenterally with a commercial J5 bacterin, and 5 cows served as controls with no parenteral vaccination. The cows were then followed over time and infection risk, clinical scores, somatic cell count, and milk production were observed over time. The results of these 10 cows showed partial protection of intramammary immunization on the outcome of a subsequent homologous intramammary challenge. Immunization resulted in a lower probability of infection, a lower bacteria count, lower somatic cell counts and milk conductivity, a lower clinical mastitis score, and increased milk production compared with unimmunized control quarters. Once the analysis was corrected for immunization, parenteral J5 vaccination had no significant effect on any of the measured parameters. These results provide the first evidence that intramammary immunization may improve the outcome of an intramammary E. coli infection in late gestation and onset of mastitis immediately following parturition. Unlike systemic vaccination, which generally does not reduce the intramammary infection risk, the intramammary immunization did show a 5-times reduced odds of an established intramammary infection after challenge. Cytokine profiles indicated a local return of proinflammatory response after challenge as the data showed a more pronounced increase in in IFN-γ with a subsequent negative feedback due to a spike in the level of IL-10 in immunized quarters relative to nonimmunized quarters. Although these results are preliminary and obtained on only 10 cows, the results provide insight into the biological benefits of triggering mucosal immunity in the mammary gland.

The value of pathogen information in treating clinical mastitis
Cha, Elva ; Smith, Rebecca L. ; Kristensen, Anders R. ; Hertl, Julia A. ; Schukken, Ynte H. ; Tauer, Loren W. ; Welcome, Frank L. ; Gröhn, Yrjö T. - \ 2016
Journal of Dairy Research 83 (2016)4. - ISSN 0022-0299 - p. 456 - 463.
dairy - mastitis - Value of information

The objective of this study was to determine the economic value of obtaining timely and more accurate clinical mastitis (CM) test results for optimal treatment of cows. Typically CM is first identified when the farmer observes recognisable outward signs. Further information of whether the pathogen causing CM is Gram-positive, Gram-negative or other (including no growth) can be determined by using on-farm culture methods. The most detailed level of information for mastitis diagnostics is obtainable by sending milk samples for culture to an external laboratory. Knowing the exact pathogen permits the treatment method to be specifically targeted to the causation pathogen, resulting in less discarded milk. The disadvantages are the additional waiting time to receive test results, which delays treating cows, and the cost of the culture test. Net returns per year (NR) for various levels of information were estimated using a dynamic programming model. The Value of Information (VOI) was then calculated as the difference in NR using a specific level of information as compared to more detailed information on the CM causative agent. The highest VOI was observed where the farmer assumed the pathogen causing CM was the one with the highest incidence in the herd and no pathogen specific CM information was obtained. The VOI of pathogen specific information, compared with non-optimal treatment of Staphylococcus aureus where recurrence and spread occurred due to lack of treatment efficacy, was $20.43 when the same incorrect treatment was applied to recurrent cases, and $30.52 when recurrent cases were assumed to be the next highest incidence pathogen and treated accordingly. This indicates that negative consequences associated with choosing the wrong CM treatment can make additional information cost-effective if pathogen identification is assessed at the generic information level and if the pathogen can spread to other cows if not treated appropriately.

Bayesian integration of sensor information and a multivariate dynamic linear model for prediction of dairy cow mastitis
Jensen, Dan B. ; Hogeveen, Henk ; Vries, Albert de - \ 2016
Journal of Dairy Science 99 (2016)9. - ISSN 0022-0302 - p. 7344 - 7361.
Bayesian classifier - dynamic linear model - mastitis

Rapid detection of dairy cow mastitis is important so corrective action can be taken as soon as possible. Automatically collected sensor data used to monitor the performance and the health state of the cow could be useful for rapid detection of mastitis while reducing the labor needs for monitoring. The state of the art in combining sensor data to predict clinical mastitis still does not perform well enough to be applied in practice. Our objective was to combine a multivariate dynamic linear model (DLM) with a naïve Bayesian classifier (NBC) in a novel method using sensor and nonsensor data to detect clinical cases of mastitis. We also evaluated reductions in the number of sensors for detecting mastitis. With the DLM, we co-modeled 7 sources of sensor data (milk yield, fat, protein, lactose, conductivity, blood, body weight) collected at each milking for individual cows to produce one-step-ahead forecasts for each sensor. The observations were subsequently categorized according to the errors of the forecasted values and the estimated forecast variance. The categorized sensor data were combined with other data pertaining to the cow (week in milk, parity, mastitis history, somatic cell count category, and season) using Bayes’ theorem, which produced a combined probability of the cow having clinical mastitis. If this probability was above a set threshold, the cow was classified as mastitis positive. To illustrate the performance of our method, we used sensor data from 1,003,207 milkings from the University of Florida Dairy Unit collected from 2008 to 2014. Of these, 2,907 milkings were associated with recorded cases of clinical mastitis. Using the DLM/NBC method, we reached an area under the receiver operating characteristic curve of 0.89, with a specificity of 0.81 when the sensitivity was set at 0.80. Specificities with omissions of sensor data ranged from 0.58 to 0.81. These results are comparable to other studies, but differences in data quality, definitions of clinical mastitis, and time windows make comparisons across studies difficult. We found the DLM/NBC method to be a flexible method for combining multiple sensor and nonsensor data sources to predict clinical mastitis and accommodate missing observations. Further research is needed before practical implementation is possible. In particular, the performance of our method needs to be improved in the first 2 wk of lactation. The DLM method produces forecasts that are based on continuously estimated multivariate normal distributions, which makes forecasts and forecast errors easy to interpret, and new sensors can easily be added.

Failure and preventive costs of mastitis on Dutch dairy farms
Soest, Felix J.S. van; Santman-Berends, Inge M.G.A. ; Lam, Theo J.G.M. ; Hogeveen, Henk - \ 2016
Journal of Dairy Science 99 (2016)10. - ISSN 0022-0302 - p. 8365 - 8374.
dairy - economics - management - mastitis

Mastitis is an important disease from an economic perspective, but most cost assessments of mastitis include only the direct costs associated with the disease (e.g., production losses, culling, and treatment), which we call failure costs (FC). However, farmers also invest time and money in controlling mastitis, and these preventive costs (PC) also need to be taken into account. To estimate the total costs of mastitis, we estimated both FC and PC. We combined multiple test-day milk records from 108 Dutch dairy farms with information on applied mastitis prevention measures and farmers’ registration of clinical mastitis for individual dairy cows. The aim was to estimate the total costs of mastitis and to give insight into variations between farms. We estimated the average total costs of mastitis to be 240/lactating cow per year, in which FC contributed 120/lactating cow per year and PC contributed another 120/lactating cow per year. Milk production losses, discarded milk, and culling were the main contributors to FC, at 32, 20, and 20/lactating cow per year, respectively. Labor costs were the main contributor to PC, next to consumables and investments, at 82, 34, and 4/lactating cow per year, respectively. The variation between farmers was substantial, and some farmers faced both high FC and PC. This variation may have been due to structural differences between farms, different mastitis-causing pathogens, the time at which preventive action is initiated, stockmanship, or missing measures in PC estimates. We estimated the minimum FC to be 34 per lactating cow per yr. All farmers initiated some preventive action to control or reduce mastitis, indicating that farmers will always have mastitis-related costs, because mastitis will never be fully eradicated from a farm. Insights into both the PC and FC of a specific farm will allow veterinary advisors and farmers to assess whether current udder health strategies are appropriate or whether there is room for improvement from an economic perspective.

Gezonde uiers goed voor koe en portemonnee : Henk Hogeveen: 'kosten mastitis verdubbelen in post-quotumtijdperk'
Versteeg, D. ; Hogeveen, H. - \ 2015
Veeteelt 32 (2015)16. - ISSN 0168-7565 - p. 43 - 43.
melkveehouderij - mastitis - uiers - diergezondheid - ziektepreventie - dierenwelzijn - dierlijke productie - melkvee - dairy farming - udders - animal health - disease prevention - animal welfare - animal production - dairy cattle
Op veel bedrijven is mastitis een onderschatte kostenpost waarbij een bedrijfsspecifieke aanpak op basis van beschikbare data loont. Dit bleek tijdens de masterclass uiergezondheid voor dierenartsen, georganiseerd door Gezondheidsdienst voor Dieren en DeLaval in Steenwijk.
Effect of sensor systems for cow management on milk production, somatic cell count and reproduction
Steeneveld, W. ; Vernooij, J.C.M. ; Hogeveen, H. - \ 2015
Journal of Dairy Science 98 (2015). - ISSN 0022-0302 - p. 3896 - 3905.
dutch dairy farms - estrus detection - activity meters - detecting cows - mastitis - lameness - cattle - health
To improve management on dairy herds, sensor systems have been developed that can measure physiological, behavioral, and production indicators on individual cows. It is not known whether using sensor systems also improves measures of health and production in dairy herds. The objective of this study was to investigate the effect of using sensor systems on measures of health and production in dairy herds. Data of 414 Dutch dairy farms with (n=152) and without (n=262) sensor systems were available. For these herds, information on milk production per cow, days to first service, first calving age, and somatic cell count (SCC) was provided for the years 2003 to 2013. Moreover, year of investment in sensor systems was available. For every farm year, we determined whether that year was before or after the year of investment in sensor systems on farms with an automatic milking system (AMS) or a conventional milking system (CMS), or whether it was a year on a farm that never invested in sensor systems. Separate statistical analyses were performed to determine the effect of sensor systems for mastitis detection (color, SCC, electrical conductivity, and lactate dehydrogenase sensors), estrus detection for dairy cows, estrus detection for young stock, and other sensor systems (weighing platform, rumination time sensor, fat and protein sensor, temperature sensor, milk temperature sensor, urea sensor, ß-hydroxybutyrate sensor, and other sensor systems). The AMS farms had a higher average SCC (by 12,000cells/mL) after sensor investment, and CMS farms with a mastitis detection system had a lower average SCC (by 10,000cells/mL) in the years after sensor investment. Having sensor systems was associated with a higher average production per cow on AMS farms, and with a lower average production per cow on CMS farms in the years after investment. The most likely reason for this lower milk production after investment was that on 96% of CMS farms, the sensor system investment occurred together with another major change at the farm, such as a new barn or a new milking system. Most likely, these other changes had led to a decrease in milk production that could not be compensated for by the use of sensor systems. Having estrus detection sensor systems did not improve reproduction performance. Labor reduction was an important reason for investing in sensor systems. Therefore, economic benefits from investments in sensor systems can be expected more from the reduction in labor costs than from improvements in measures of health and production in dairy herds.
Dertig dagen droog voldoende
Drie, I. van; Knegsel, A. van; Lam, T.G.J.M. ; Koopmans, A. - \ 2015
Veeteelt 32 (2015)1. - ISSN 0168-7565 - p. 54 - 55.
melkveehouderij - melkkoeien - lactatie - gustperiode - strategisch management - mastitis - dairy farming - dairy cows - lactation - dry period - strategic management
De afronding van het project Why Dry van Wageningen Universiteit is aanleiding om stil te staan bij de droogstand. Wat is de ideale droogstandslengte? Is doormelken of het weglaten van de droogstand aan te raden en zorgt selectief droogzetten voor meer mastitisgevallen? Veeteelt zet aan de hand van zeven vragen de onderzoeksresultaten op een rij.
Characterization of Dutch dairy farms using sensor systems for cow management
Steeneveld, W. ; Hogeveen, H. - \ 2015
Journal of Dairy Science 98 (2015)1. - ISSN 0022-0302 - p. 709 - 717.
automatic milking system - estrus detection - activity meters - detecting cows - cattle - mastitis - lameness
To improve cow management in large dairy herds, sensors have been developed that can measure physiological, behavioral, and production indicators on individual cows. Recently, the number of dairy farms using sensor systems has increased. It is not known, however, to what extent sensor systems are used on dairy farms, and the reasons why farmers invest or not in sensor systems are unclear. The first objective of this study was to give an overview of the sensor systems currently used in the Netherlands. The second objective was to investigate the reasons for investing or not investing in sensor systems. The third objective was to characterize farms with and without sensor systems. A survey was developed to investigate first, the reasons for investing or not in sensor systems and, then, how the sensor systems are used in daily cow management. The survey was sent to 1,672 Dutch dairy farmers. The final data set consisted of 512 dairy farms (response rate of 30.6%); 202 farms indicated that they had sensor systems and 310 farms indicated that they did not have sensor systems. A wide variety of sensor systems was used on Dutch dairy farms; those for mastitis detection and estrus detection were the most-used sensor systems. The use of sensor systems was different for farms using an automatic milking system (AMS) and a conventional milking system (CMS). Reasons for investing were different for different sensor systems. For sensor systems attached to the AMS, the farmers made no conscious decision to invest: they answered that the sensors were standard in the AMS or were bought for reduced cost with the AMS. The main reasons for investing in estrus detection sensor systems were improving detection rates, gaining insights into the fertility level of the herd, improving profitability of the farm, and reducing labor. Main reasons for not investing in sensor systems were economically related. It was very difficult to characterize farms with and without sensor systems. Farms with CMS and sensor systems had more cows than CMS farms without sensor systems. Furthermore, farms with sensor systems had fewer labor hours per cow compared with farms without sensor systems. Other farm characteristics (age of the farmer, availability of a successor, growth in herd size, milk production per cow, number of cows per hectare, and milk production per hectare) did not differ for farms with and without sensor systems.
The relationship between farmers’ participation in veterinary herd health management programs and farm performance
Derks, M. ; Werven, T. van; Hogeveen, H. ; Kremer, W.D.J. - \ 2014
Journal of Dairy Science 97 (2014)3. - ISSN 0022-0302 - p. 1336 - 1347.
dutch dairy farmers - netherlands - mastitis - prevention - objectives - perception - attitudes - behavior - cattle - costs
In the past few decades, farms have increased in size and the focus of management has changed from curative to preventive. To help farmers cope with these changes, veterinarians offer veterinary herd health management (VHHM) programs, whose major objective is to support the farmer in reaching his farm performance goals. The association between farm performance and participation in VHHM, however, remains unknown. The aim of this paper was to compare farm performance parameters between participants and nonparticipants in VHHM and to differentiate within participation to evaluate the possible added value of VHHM on the farm. Five thousand farmers received a questionnaire about the level of VHHM on their farm. Farm performance parameters of these 5,000 farms were provided. For all respondents (n = 1,013), farm performance was compared between participants and nonparticipants and within level of participation, using linear mixed and linear regression models. Farmers who participated in VHHM produced 336 kg of milk/cow per year more and their average milk somatic cell count (SCC) was 8,340 cells/mL lower than farmers who did not participate in VHHM. Participating herds, however, had an older age at first calving (+12 d), a lower 56-d nonreturn rate percentage (-3.34%), and a higher number of inseminations per cow (+0.09 inseminations). They also had more cows culled per year (+1.05%), and a lower age at culling (-70 d). Participants in the most-extended form of VHHM (level 3) had a lower SCC (-19,800 cells/mL), fewer cows with high SCC (-1.70%), fewer cows with new high SCC (-0.47%), a shorter calving interval (-6.01 d), and fewer inseminations per heifer (-0.07 inseminations) than participants in the least-extended form of VHHM (level 1). Level 3 participants, however, also had more cows culled per year (+1.74%) and a lower age at culling (-103 d). Discussing specific topics with the veterinarian (milk production, fertility, and udder health) had only marginal effects on improving the farm performance parameters related to those topics. Given the relevance of fertility on the farm and the focus on longevity by society, it is important to determine underlying reasons for the negative associations of these topics with participation in VHHM. A longitudinal study could provide answers to this. For now, veterinarians should be aware of the associations. The increased milk production and milk quality could help the marketing of VHHM to farmers.
Financial aspects of veterinary herd health management programmes
Ifende, V.I. ; Derks, M. ; Hooijer, G.A. ; Hogeveen, H. - \ 2014
Veterinary Record 175 (2014)9. - ISSN 0042-4900
dutch dairy farms - netherlands - mastitis - cattle - cows - objectives - diseases - model
Veterinary herd health management (VHHM) programmes are meant to support herd health and farmers’ income (Brand and Guard 1996). They were introduced in the Netherlands in the 1970s (Sol and Renkema 1984) and at present many veterinarians provide them to farmers. VHHM comprises a basic structure of goal setting, planning, execution and evaluation. Farms are visited every four to six weeks, where the veterinarian inspects the animals, evaluates gathered data and provides advice (Brand and Guard 1996). Ideally, VHHM combines animal health, food safety, animal welfare and public health with farm management and economics (Noordhuizen and Wentink 2001, LeBlanc and others 2006). VHHM programmes are used not only in the Netherlands, but on a wider scale, for instance in the UK (Wassell and Esslemont 1992) and Denmark (Kristensen and Enevoldsen 2008). The farmers in Europe have to produce under strict, often expensive and laborious, regulations while competing with commercial farmers outside the EU who are not subjected to the same rules (Cannas de Silva and others 2006). As dairy farmers strive for further efficiency in production, driven by market economics, the risks and consequences of poor health and suboptimal production increase (Sibley 2006). VHHM programmes are meant to help farmers to produce products of high quality for a low cost price (Brand and Guard 1996). Its primary objectives include the optimisation of herd health, productivity, quality of products and profitability of the dairy enterprise (Blood and others 1978). In practice, some farms or veterinarians embrace the concepts of VHHM by active participation, while others do not (Derks and others 2012). Also, veterinarians are not always able to meet farmers’ requirements for VHHM (Hall and Wapenaar 2012, Derks 2013). Its efficiency is hard to determine. There is, for instance, no recent information on the cost implications of this programme with regard to perceived profitability in farms. A limited number of controlled studies were carried out in the early 1970s and 1980s to evaluate the effects of VHHM on farm performance (Williamson 1980, Sol and others 1984). It was shown that a VHHM programme produced considerable benefits to participating farmers. A follow-up study showed approximately 8 per cent increase in margin per cow compared with the initial margin, using 1974–1975 as a base year (Hogeveen and others 1992). Since that time, no economic studies were carried out on the effects of these programmes. This study evaluates the economic relationship between participation in a VHHM programme and farm performance on dairy farms and estimates the costs incurred by the participation in this programme as well as the net returns (NR), including factors that influence the NR on a farm.
Do farm audits improve milk quality?
Flores-Miyamoto, A. ; Reij, M.W. ; Velthuis, A.G.J. - \ 2014
Journal of Dairy Science 97 (2014)1. - ISSN 0022-0302 - p. 1 - 9.
bulk tank milk - total bacterial count - somatic-cell counts - product quality - risk-factors - food safety - level - contamination - mastitis - health
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. Key words bulk milk; certification scheme; second-party audit; hygiene
Genetic parameters for natural antibody isotype titers in milk of Dutch Holstein-Friesians
Wijga, S. ; Bovenhuis, H. ; Bastiaansen, J.W.M. ; Arendonk, J.A.M. van; Ploegaert, T.C.W. ; Tijhaar, E. ; Poel, J.J. van der - \ 2013
Animal Genetics 44 (2013)5. - ISSN 0268-9146 - p. 485 - 492.
immunoglobulin-a - innate immunity - laying hens - responses - mastitis - cattle - cows - lactation - survival
The objective of the present study was to estimate genetic parameters for natural antibody isotypes immunoglobulin (Ig) A, IgG1 and IgM titers binding the bacterial antigens lipopolysaccharide, peptidoglycan and the model antigen keyhole limpet hemocyanin in Dutch Holstein-Friesian cows (n = 1695). Further, this study included total natural antibody titers binding the antigens mentioned above, making no isotype distinction, as well as total natural antibody titers and natural antibody isotypes IgA, IgG1 and IgM binding lipoteichoic acid. The study showed that natural antibody isotype titers are heritable, ranging from 0.06 to 0.55, and that these heritabilities were generally higher than heritabilities for total natural antibody titers. Genetic correlations, the combinations of total natural antibody titers and natural antibody isotype titers, were nearly all positive and ranged from -0.23 to 0.99. Strong genetic correlations were found between IgA and IgM. Genetic correlations were substantially weaker when they involved an IgG1 titer, indicating that IgA and IgM have a common genetic basis, but that the genetic basis for IgG1 differs from that for IgA or IgM. Results from this study indicate that natural antibody isotype titers show the potential for effective genetic selection. Further, natural antibody isotypes may provide a better characterization of different elements of the immune response or immune competence. As such, natural antibody isotypes may enable more effective decisions when breeding programs start to include innate immune parameters.
Variance component and breeding value estimation for genetic heterogeneity of residual variance in Swedish Holstein dairy cattle
Rönnegård, L. ; Felleki, M. ; Fikse, W.F. ; Mulder, H.A. ; Strandberg, E. - \ 2013
Journal of Dairy Science 96 (2013)4. - ISSN 0022-0302 - p. 2627 - 2636.
generalized linear-models - nellore beef-cattle - somatic-cell score - phenotypic variability - milk-production - weight traits - selection - lactation - mastitis - records
Trait uniformity, or micro-environmental sensitivity, may be studied through individual differences in residual variance. These differences appear to be heritable, and the need exists, therefore, to fit models to predict breeding values explaining differences in residual variance. The aim of this paper is to estimate breeding values for micro-environmental sensitivity (vEBV) in milk yield and somatic cell score, and their associated variance components, on a large dairy cattle data set having more than 1.6 million records. Estimation of variance components, ordinary breeding values, and vEBV was performed using standard variance component estimation software (ASReml), applying the methodology for double hierarchical generalized linear models. Estimation using ASReml took less than 7 d on a Linux server. The genetic standard deviations for residual variance were 0.21 and 0.22 for somatic cell score and milk yield, respectively, which indicate moderate genetic variance for residual variance and imply that a standard deviation change in vEBV for one of these traits would alter the residual variance by 20%. This study shows that estimation of variance components, estimated breeding values and vEBV, is feasible for large dairy cattle data sets using standard variance component estimation software. The possibility to select for uniformity in Holstein dairy cattle based on these estimates is discussed.
Vaccineren tegen uierontsteking werkt
Livestock Research, - \ 2012
dairy farming - dairy cows - mastitis - vaccination - udders - cattle diseases - animal disease prevention - somatic cell count
Foot disorders in dairy cattle: impact on cow and dairy farmer
Bruijnis, M.R.N. ; Beerda, B. ; Hogeveen, H. ; Stassen, E.N. - \ 2012
Animal Welfare 21 (2012)suppl. 1. - ISSN 0962-7286 - p. 33 - 40.
holstein cows - claw disorders - lameness control - milk-yield - prevalence - associations - mastitis - heifers - england - health
This paper considers the economic consequences and the welfare impact of foot disorders in dairy cattle and the association between them, taking into account clinical and subclinical foot disorders. In dairy farming with cubicle housing and concrete floors, foot disorders are a major welfare problem with serious economic consequences. On average, foot disorders cost €53 per cow per year, of which indirect cost factors are the main cause. Subclinical foot disorders, which are the foot disorders not recognised by dairy farmers, account for 50% of the total welfare impact and 32% of the total costs. The consequences of foot disorders can be difficult to observe and more insight into these consequences is helpful in stimulating actions to improve dairy cow foot health. Digital dermatitis (DD), an infectious foot disorder, is the most serious foot disorder from both an economic and welfare perspective. The correlation between economics and animal welfare impact suggests that reducing the problem of foot disorders from an economic perspective will positively influence the welfare of dairy cows. Insight into economic and welfare consequences of the different foot disorders, including the association between them, can help make dairy farmers more aware and help with decision-making regarding measures to improve dairy cow foot health. Keywords: animal welfare, dairy cattle, economics, foot disorders, modelling, welfare impact
Genetic aspects of somatic cell count and udder health in the Italian Valle del Belice dairy sheep
Riggio, V. - \ 2012
Wageningen University. Promotor(en): Johan van Arendonk, co-promotor(en): Henk Bovenhuis; B. Portolano. - [S.l. : s.n. - ISBN 9789461732460 - 137
ovis - schapen - schapenziekten - uiers - mastitis - celgetal - genetica - melkveehouderij - dierveredeling - italië - ovis - sheep - sheep diseases - udders - mastitis - somatic cell count - genetics - dairy farming - animal breeding - italy

Mastitis is an inflammation of the udder, which leads to economic loss, mainly consisting of discarded milk, reduced milk production and quality, and increased health costs. Somatic cell count (SCC), and therefore somatic cell score (SCS), is widely used as indicator of mastitis. In this thesis, I focus on the genetic parameters of SCS as indicator of mastitis, and on the possibilities of using this trait for selection for mastitis resistance in the Valle del Belice dairy sheep.

In Chapter 1, mastitis and SCS are defined and introduced. Chapter 2 deals with the estimation of genetic parameters for SCS and milk production traits in primiparous Valle del Belice ewes. Heritability estimates ranged from 0.09 to 0.14 for milk, fat and protein yields and contents. For SCS, the heritability of 0.14 was relatively high. SCS was genetically positively correlated to milk, fat and protein yields and contents. However, correlations were not extreme, so simultaneous improvement for milk yield and SCS seems possible. In Chapter 3, the level of SCC is included in a survival analysis to evaluate the effect of SCC on functional longevity. Results showed that an increase in SCC was associated with an increase in culling rate.Elevated SCC, therefore, play an indirect role in the culling decisions of Valle del Belice dairy sheep farmers, although, at present, farmers do not directly select for reduced SCC. In Chapter 4, the genetic parameters of the infection status and SCS, according to whether the samples were bacteria negative or positive are reported. Moreover, the impact of imperfect sensitivity and specificity on variance component estimates was investigated. The heritability was 0.10 for bacteria negative SCS, 0.03 for bacteria positive SCS, and 0.09 for infection status, on the liability scale. The genetic correlation between bacteria negative and bacteria positive SCS (0.62) suggests that they may be genetically different traits, confirming that SCSfrom healthy and infected animals should be analyzed separately. Moreover, a positive genetic correlation between bacteria negative SCS and liability to mastitis was found, suggesting that the approach of selecting animals for decreased SCS will help to reduce the prevalence of mastitis. The results also showed that the imperfect diagnosis of infection has an impact on estimated genetic parameters,which may reduce the efficiency of selection strategies aiming at distinguishing between bacteria negative and bacteria positive SCS. In Chapter 5, the diagnostic ability of SCCand California Mastitis Test (CMT) to detect intramammary infectionswas evaluated by using the Receiver-Operating Characteristic(ROC) curves, in order to identify a SCCthreshold that better discriminated healthy from infected udders. The results indicate that the CMT can only discriminate the udders infected from major pathogens. Nevertheless, in general SCS was the best indirect test for the bacteriological status of the udder.

The final chapter explores and discusses the opportunities to use SCS as indicator of mastitis in a selection scheme to improve mastitis resistance for the Valle del Belice dairy sheep breed.

Lungworm outbreaks in adult dairy cows: estimating economic losses and lessons to be learned
Holzhauer, M. ; Schaik, G. van; Saatkamp, H.W. ; Ploeger, H.W. - \ 2011
Veterinary Record 169 (2011)19. - ISSN 0042-4900
virus serotype 8 - dictyocaulus-viviparus - cattle - infection - resistance - mastitis - immunity - costs - herds
Two lungworm outbreaks in dairy herds were investigated in order to estimate the resulting economic costs. On the two farms, with 110 and 95 cows, total costs were estimated at (sic)159 and (sic)167 per cow, respectively. Overall, milk production reduced by 15 to 20 per cent during the outbreaks. Five cows died on one farm, while on the other farm seven cows died as a result of the lungworm outbreak. On one farm, 51.7 per cent of the total costs was due to reduced milk production and 33.1 per cent was due to disposal of dead animals. On the other farm, it was 36.3 and 50.9 per cent, respectively. The remaining 13 to 15 per cent of the total costs were due to extra inseminations, laboratory diagnosis and treatments. The history and development of the outbreaks are described. One lesson from these outbreaks is that recognising that potentially lungworm-naive animals are to be introduced into the adult herd allows for timely measures (for example, vaccination) to prevent a lungworm outbreak.
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