Associations between farmer participation in veterinary herd health management programs and farm performance.

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 (+12d), 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.

Veterinary herd health management programs on dairy farms in the Netherlands: use, execution, and relations to farmer characteristics.

Veterinary herd health management (VHHM) programs are of growing importance to the dairy industry; they support farmers in the shift from curative to preventive health management, caused by increased herd sizes and quality standards in dairy farming. Farmers participating in VHHM are visited every 4 to 6 wk by their veterinarian, who checks the animals and herd management to intervene in a proactive way with problems regarding animal health and animal welfare. At present, no good overview exists of how VHHM is executed on Dutch dairy farms, and whether different farmers require different types of VHHM. Aims of this study were to (1) map out how many farmers participate in VHHM, (2) describe how VHHM is executed on the farms, and (3) see whether certain farmer characteristics are related to farmers' participation in VHHM. In 2011, a questionnaire was sent to 5,000 Dutch dairy farmers per e-mail. Part 1 of the questionnaire focused on participation in and execution of VHHM and part 2 focused on farmer characteristics regarding external information. Returned questionnaires (n=1,013) were summarized and statistically analyzed. In this study 68.6% of the responding farmers participated in any form of VHHM. The most important activities were fertility checks and advice about fertility; the least important were housing and claw health. Relationships between farmer characteristics (use of and trust in information) and participation in VHHM were found.

Short communication: influence of sampling interval on the accuracy of predicting bulk milk somatic cell count.

Although bulk milk somatic cell count (BMSCC) is, in most instances, not a good proxy for actual average herd somatic cell count (SCC), BMSCC is the only SCC parameter available to monitor trends in udder health for a large number of farms worldwide. The frequency of sampling BMSCC varies considerably between countries, and it is unknown to what extent the sampling interval of BMSCC or variation in BMSCC data itself influences the accuracy. The aim of this study was to assess the effect of sampling interval and variation of the BMSCC data on the accuracy to predict BMSCC. Because BMSCC is measured at regular time intervals, an artificial neural network (ANN) was used to determine both the effect of sampling interval and variation of the BMSCC data. The intervals examined in this study ranged from 4 to 14 d and were compared with the baseline of a standard 2-d sampling interval. The BMSCC data were collected every other day for a 24-mo period on 949 farms, and all series were created by exclusion of BMSCC data in between the original 2-d sampling interval series. The effect of variation of BMSCC was determined by comparing the error of the ANN model in 2 subsets of farms, those with the lowest SD (n=239) and those with a high SD of BMSCC data (n=236). No significant differences were found in any of the sampling intervals between the 2 cohorts of low and high SD in BMSCC. Overall, compared with the 2-d sampling interval, on average the error of the ANN model was 32,600 cells/mL for all farms included, ranging from 15,000 cells/mL (4-d interval) to 41,000 cells/mL (14-d sampling interval). Therefore, the length of the sampling interval greatly influences the usefulness of BMSCC data to monitor trends in udder health at the herd level.

Prediction of the herd somatic cell count of the following month using a linear mixed effect model.

An accurate prediction of the average somatic cell count (SCC) for the next month would be a valuable tool to support udder health management decisions. A linear mixed effect (LME) model was used to predict the average herd SCC (HSCC) for the following month. The LME model included data on SCC, herd characteristics, season, and management practices determined in a previous study that quantified the contribution of each factor for the HSCC. The LME model was tested on a new data set of 101 farms and included data from 3 consecutive years. The farms were split randomly in 2 groups of 50 and 51 farms. The first group of 50 farms was used to check for systematic errors in predicting monthly HSCC. An initial model was based on older data from a different part of the Netherlands and systematically overestimated HSCC in most months. Therefore, the model was adjusted for the difference in average HSCC between the 2 sets of farms (from the previous and current study) using the data from the first group of 50 farms. Subsequently, the data from the second group of 51 farms were used to independently assess this final model. A null model (no explanatory variables included) predicted 48 and 59% of the HSCC within the predetermined range of 20,000 and 30,000 cells/mL, respectively. The final LME model predicted 72 and 81% of the HSCC of the next month correctly within these 2 ranges. These outcomes indicate that the final LME model was a valid additional tool for farmers that could be useful in their short-term decisions regarding udder health management and could be included in dairy herd health programs.

[Evaluation of veterinary advice given to dairy farmers]. / Beoordeling van de bedrijfsadvisering door dierenartsen op rundveebedrijven.

In this pilot study, the manner and effectiveness of advice given by four cattle practitioners was investigated during health management visits to 34 dairy farms. Farmers were asked about their satisfaction with the advice given, and an independent observer evaluated the manner in which practitioners carried out the farm visit. There were no major differences between the cattle practitioners, but there were minor differences in the way practitioners gave advice, in the duration of the herd visit, and in the subjects talked about. The farmers were positive about the manner in which advice was given and its effect. The method used in this pilot study could be used to gain insight into the manner in which veterinary advice is given by veterinary practitioners and veterinary practices, and may contribute to improving the quality of veterinary services provided.

Effect of herd characteristics, management practices, and season on different categories of the herd somatic cell count.

In this study, the contribution of management practices, herd characteristics, and seasonal variables to the herd somatic cell count (SCC) was quantified in herds with low (<150,000 cells/mL), medium (150,000-200,000 cells/mL), and high (>200,000 cells/mL) herd SCC (HSCC). Selection of the variables was performed using a linear mixed effect model; HSCC was calculated as the arithmetic mean of the individual cow's SCC. The data concerning management practices were derived from 3 questionnaires on mastitis prevention and management practices on 246 Dutch dairy farms. The monthly Dairy Herd Improvement test data of these 246 farms were used to calculate the herd characteristics and seasonal effects. None of the management practices were associated with HSCC in all 3 HSCC categories. Some variables only had a significant association with HSCC in one HSCC category, such as dry premilking treatment (-9,100 cells/mL in the low HSCC category) or feeding calves with high SCC milk (11,100 cells/ mL in the medium HSCC category). Others had an opposite effect on HSCC in different HSCC categories, such as average parity (-6,400 and 11,000 cells/mL in the low and medium HSCC category, respectively) and feeding calves with fresh milk (10,300 and -9,700 cells/ mL in the low and high HSCC category, respectively). We conclude that, given the individual Dairy Herd Improvement data and information on management practices of an individual farm, it is possible to provide quantitative insight into the contribution of these different variables to the HSCC of an individual farm. Being able to provide such insight is a prerequisite for interpretation, prediction, and control of HSCC on individual dairy farms.

Short communication: Comparison of bulk milk, yield-corrected, and average somatic cell counts as parameters to summarize the subclinical mastitis situation in a dairy herd.

In this study, the correlation was determined between the prevalence of high cow-level somatic cell count (SCC >250,000 cells/mL), a summary of the subclinical mastitis situation in a dairy herd, and 3 average herd SCC parameters: bulk milk SCC (BMSCC), yield-corrected test-day SCC (CHSCC), and the arithmetic average test-day SCC (HSCC) of the lactating herd. The herd prevalence of cows with an SCC of >250,000 cells/mL was calculated by using Dairy Herd Improvement data. Herds were included if BMSCC was sampled within 2 d of the Dairy Herd Improvement test day and if the BMSCC did not exceed 400,000 cells/mL. The interval between sampling, 0, 1, or 2 d, did not significantly influence the correlation between BMSCC and the prevalence of high SCC. The correlations between the prevalence of high SCC and BMSCC, yield-corrected test-day SCC, and HSCC, examined by using a linear regression model, were 0.64, 0.78, and 0.89, respectively. Therefore, it can be concluded that, based on the highest correlation, HSCC is a more appropriate parameter than BMSCC to summarize the average herd subclinical mastitis situation in a dairy herd.

[Veterinary herd health consultancy on dairy farms: guidelines for starters]. / Veterinaire advisering van melkveebedrijven: een leidraad voor starters.

This paper presents a guideline which can be used when setting up a professional veterinary herd health and production management advisory programme for dairy farms. Earlier research showed that dairy farmers prefer a structured professional programme and ask their veterinary surgeons to provide an optimal veterinary advisory programme for their dairy farms with a clear structure and contents, and well-planned activities. The guideline presented here should aid in providing the farmers with that clarity, structure, and planning. This should ultimately lead to a more professional implementation of veterinary advisory programmes.

An attempt to control lungworm disease and parasitic gastroenteritis on commercial dairy farms by the use of an adaptation of Michel's dose-and-move system.

On seven dairy farms an attempt was made to control lungworm disease in calves by turnout on a pasture grazed earlier by cows, followed by a move to aftermath and ivermectin treatment 2 months later. Transmission of lungworm was observed on all farms. Lungworm disease occurred on four farms at treatment. Coughing re-occurred on three of these farms in some animals 2 months later. Owing to poor performance between turnout and treatment, weight gain was below the norm on the farm with the highest infections and most severe respiratory signs. On the other farms respiratory signs did not result in poor weight gain. Gastrointestinal nematode infections remained low on all farms. The conclusion is that this dose and move scheme cannot be recommended for the control of lungworm.

A knowledge-based system for diagnosis of mastitis problems at the herd level. 1. Concepts.

Much specialized knowledge is involved in the diagnosis of a mastitis problem at the herd level. Because of their problem-solving capacities, knowledge-based systems can be very useful to support the diagnosis of mastitis problems in the herd. Conditional causal models with multiple layers are used as a representation scheme for the development of a knowledge-based system for diagnosing mastitis problems. Construction of models requires extensive cooperation between the knowledge engineer and the domain expert. The first layer consists of three overview models: the general overview conditional causal model, the contagious overview conditional causal model, and the environmental overview conditional causal model, giving a causal description of the pathways through which mastitis problems can occur. The conditional causal model for primary udder defense and the conditional causal model for host defense are attached to the overview models at the second layer, and the conditional causal model for deep primary udder defense is attached to the conditional causal model for the primary udder defense at the third layer. Based on quantitative user input, the system determines the qualitative values of the nodes that are used for reasoning. The developed models showed that conditional causal models are a good method for modeling the mechanisms involved in a mastitis problem. The system needs to be extended in order to be useful in practical circumstances.

[Pathogenic studies of Escherichia coli mastitis]. / Pathogenetisch onderzoek naar Escherichia coli mastitis.

In this paper research about the pathogenesis of Escherichia coli mastitis, executed by the Department of Herd Health and Reproduction, is reviewed. The use of experimental infection models to study the systemic clinical symptoms of an Escherichia coli mastitis and the effect of anti-inflammatory drugs on this symptoms are described. Additionally, correlations between pre-infection in vitro leucocyte function tests and the severity of an Escherichia coli infection are discussed. Finally, some future developments and their possible applications are revealed.

Role of the neutrophil leucocyte in the local and systemic reactions during experimentally induced E. coli mastitis in cows immediately after calving.

Mammary leucocytes are the major contributors to natural defence against mastitis after a microorganism has entered the gland. This paper reviews the role of the neutrophil granulocyte during acute coliform mastitis in cows in the periparturient period. Qualitative and quantitative aspects of several neutrophil cell functions before and during experimentally induced infections are briefly discussed.

Severity of experimental Escherichia coli mastitis in ketonemic and nonketonemic dairy cows.

The severity of experimental Escherichia coli mastitis in relation to in vitro chemotaxis of polymorphonuclear leukocytes was investigated in cows during negative energy balance. The negative energy balance was induced by feed restriction. Cows were classified into two groups, ketonemic and nonketonemic, based on the beta-hydroxybutyrate concentration in the peripheral blood at the moment of inoculation. Bacterial growth in the inoculated quarter was used as a parameter to indicate the severity of experimental mastitis. In the nonketonemic cows, experimental mastitis ranged from moderate to severe. Severity of experimental mastitis was negatively related to preinfection chemotactic response of polymorphonuclear leukocytes. In contrast, the course of experimental mastitis in the ketonemic group was relatively severe in all cows, regardless of preinfection chemotactic response.

Blood polymorphonuclear leukocyte chemotaxis during experimental Escherichia coli bovine mastitis.

The relationship between the severity of experimental Escherichia coli mastitis and the chemotactic response of blood polymorphonuclear leukocytes was investigated before and during mastitis. Experimental E. coli mastitis was induced in 10 healthy cows by inoculation of the rear right quarters with 10(3) cfu of E. coli. Cows were classified into two groups based on the severity of the mastitis. Bacterial growth in the inoculated quarter was used as parameter that indicated severity. Before and during experimental mastitis, the chemotactic response and the number of circulating polymorphonuclear leukocytes were greater for the moderately diseased cows than for the severely diseased cows. During the first 24 h of the experimental mastitis, the chemotactic response of polymorphonuclear leukocytes decreased in both groups. Recovery of the chemotactic response of white blood cells was more rapid in moderately diseased cows than in severely diseased cows. Possibly, the larger proportion of band neutrophils (the less chemotactically active band neutrophils) partially accounts for the lower chemotactic response of the circulating polymorphonuclear leukocytes during experimental mastitis in the severely diseased cows.

Automated feeding of milk replacer and health control of group-housed veal calves.

The behaviour, growth rate, feed intake, health and slaughter quality of group-housed veal calves fed automatically with milk replacer were compared with those of veal calves kept in individual crates and bucket-fed the same milk replacer. The growth rate and feed intakes of the group-housed calves were lower than those of the calves in individual crates. Their feed conversion rates were similar and there were no significant differences in carcase conformation. The meat of the group-housed calves was paler in colour. The feeding behaviour of the group-housed calves was studied to see whether sick animals could be identified at an early stage but behaviour alone provided an inadequate detection system. Intensive health controls in one of the trials showed that infectious respiratory and digestive diseases may be a greater problem in group-housed veal calves than in veal calves kept in crates.

Preinfection chemotactic response of blood polymorphonuclear leukocytes to predict severity of Escherichia coli mastitis.

Experimental mastitis was induced by inoculating rear right quarters of 10 healthy cows with 10(3) cfu of Escherichia coli. The chemotactic responses of peripheral blood polymorphonuclear leukocytes at d-6, -5, -2, -1, and immediately prior to inoculation were measured. Chemiluminescence of polymorphonuclear leukocytes was measured immediately prior to inoculation. Severity of the experimental mastitis was assessed by bacterial growth in the inoculated quarters. Results of this study indicated that severity of the experimental mastitis may be predicted by the chemotactic response in vitro of polymorphonuclear leukocytes isolated from the peripheral blood at d 2, d 1, and immediately prior to inoculation. The number of circulating polymorphonuclear leukocytes immediately prior to inoculation also showed a negative relationship with the severity of mastitis. No relationship existed between preinfection chemiluminescence of polymorphonuclear leukocytes and the severity of the experimental mastitis.

Classification of newly calved cows into moderate and severe responders to experimentally induced Escherichia coli mastitis.

In the present study newly calved cows were tentatively classified as moderate and severe responders to experimentally induced Escherichia coli mastitis based upon the reactive oxygen species (ROS)-generating capacity of their blood neutrophils before infection. The groups differed in blood and milk composition prior to infection. This initial classification was supported by the corresponding variation in clinical symptoms and in the changes in milk production and composition measured during mastitis. Responses of newly calved cows to Esch. coli challenge varied from mild to severe symptoms of inflammation in infected glands and differed in the intensity of systemic disturbances and general illness. Losses in milk yield and compositional changes were most pronounced in inflamed glands and in severe responders. In inflamed glands milk yield and composition did not return to preinfection level in either moderate or severe responders. The yields of lactose, alpha-lactalbumin, casein and fat followed the same pattern as milk yield. It is concluded that the severe and long lasting systemic disturbances observed in severe responders can be ascribed to absorption of endotoxin from infected glands into circulation, indicating the important role of endotoxin in the pathology of coliform mastitis in periparturient cows. Evaluation of the ROS-generating capacity of blood neutrophils and blood and milk composition before infection might help to predict the cow's sensitivity to Esch. coli mastitis.

[Mycotic mastitis in cattle]. / Mycotische mastitis bij het rund.

The literature on aetiology, diagnosis, symptoms, therapy and prognosis of mycotic mastitis in cows is reviewed. The importance of identification of the causative agent for the prognosis is discussed. Some cases of (candida) mastitis recover spontaneously: however, spontaneous recovery or recovery after therapy for mastitis caused by Cryptococcus or Prototheca is rare. Frequent milking of infected teats is important during treatment of mycotic mastitis. If supportive pharmacotherapy is desired, antimycotic drugs could be appropriate, however there is no clear evidence of the effectiveness of this therapy.

A procedure for parallel isolation of white blood cells, granulocyte and purified neutrophil suspensions from the peripheral blood of cattle.

A rapid method is described for parallel isolation of white blood cells, granulocytes and purified neutrophils from peripheral blood of normal cattle. The mean recovery (+/- S.D.) of white blood cells, granulocytes and purified neutrophils isolated from peripheral blood of 13 cows was 66.4 +/- 12.6%, 68.7 +/- 20.0% and 38.0 +/- 20.9%, respectively. The mean purity of the isolated granulocyte and neutrophil suspensions was 94.0 +/- 3.8% and 95.0 +/- 6.0%, respectively. Viability of isolated cells was more than 97%.

Host defence and bovine coliform mastitis. Host defence mechanisms and characteristics of coliform bacteria in coliform mastitis in bovine: a review.

This paper reviews the microbial properties that underlie the virulence of coliform microorganisms causing bovine mastitis. The interaction between the coliform bacteria and teat-duct defence, humoral defence and phagocytic cells is discussed. The functioning of these host-defence mechanisms seems to exert a major role in the course of a coliform infection of the udder.