Search

Veterinarians have a long history of contributing to animal and human health; simultaneously, the veterinary medical profession has held the tenet of protecting public health. Veterinary education has shifted with societal needs over time and currently has curricula at US colleges of veterinary medicine (CVMs) largely focused on clinical practice and basic sciences. The focus of many veterinary curricula produces a veterinarian who meets the needs of the US pet owner. A void often exists in the knowledge and understanding of new veterinary graduates in the field of public practice and, in particular, public health. Students need to be able to find other learning environments and opportunities that help bridge this void. This article captures possible opportunities as best practices. Advising US veterinary students interested in public health and public health policy while considering these opportunities will help to enhance the likely experiences students have during their formal veterinary education. While no list of opportunities can be inclusive of all possibilities, the experiences listed here provide a solid foundation of options for students to include in the individualized aspects of their veterinary education.

Foot and mouth disease (FMD) is a primary transboundary livestock disease of international concern. Outbreaks of the disease have recently occurred in several countries that were previously FMD-free. For countries with limited direct experience of this disease, modelling is a useful tool for the study of a potential outbreak. The objectives of this study were to determine specific FMD risk parameters for Minnesota and the United States (USA) and to use these parameters to create a baseline FMD outbreak model for Minnesota. Of specific interest was to assess whether the type of herd in which the outbreak began (a dairy herd or a large-scale swine herd) influenced the basic model outcomes of outbreak size and duration, and to examine the effects of depopulation and movement controls. The mean values for disease duration, outbreak duration and number of farms and animals infected were larger in the scenario with a dairy index herd. The results of these two outbreak models demonstrated the entire spectrum of FMD outbreak types; that is, from limited, focal outbreaks to widespread, uncontrolled outbreaks. The findings from this study provide details of a baseline model that emergency preparedness planners can use to evaluate response strategies for a potential incursion of FMD into the USA. These findings are also of value for all countries as veterinary authorities develop or adjust their FMD emergency response plans.

Nucleos(t)ide analogues that inhibit hepatitis B virus (HBV) DNA replication are typically used as monotherapy for chronically infected patients. Treatment with a nucleos(t)ide analogue eliminates most HBV DNA replication intermediates and produces a gradual decline in levels of covalently closed circular DNA (cccDNA), the template for viral RNA synthesis. It remains uncertain if levels of cccDNA decline primarily through hepatocyte death, or if loss also occurs during hepatocyte mitosis. To determine if cccDNA survives mitosis, growing ducklings infected with duck hepatitis B virus (DHBV) were treated with the nucleoside analogue, Entecavir. Viremia was suppressed at least 10(5)-fold, during a period when average liver mass increased 23-fold. Analysis of the data suggested that if cccDNA synthesis was completely inhibited, at least 49% of cccDNA survived hepatocyte mitosis. However, there was a large duck-to-duck variation in cccDNA levels, suggesting that low level cccDNA synthesis may contribute to this apparent survival through mitosis., (Crown Copyright © 2013 Published by Elsevier Inc. All rights reserved.)

Foot and mouth disease (FMD) continues to be a disease of major concern for the United States Department of Agriculture (USDA) and livestock industries. Foot and mouth disease virus is a high-consequence pathogen for the United States (USA). Live animal trade is a major risk factor for introduction of FMD into a country. This research estimates the probability of FMD being introduced into the USA via the legal importation of livestock. This probability is calculated by considering the potential introduction of FMD from each country from which the USA imports live animals. The total probability of introduction into the USA of FMD from imported livestock is estimated to be 0.415% per year, which is equivalent to one introduction every 241 years. In addition, to provide a basis for evaluating the significance of risk management techniques and expenditures, the sensitivity of the above result to changes in various risk parameter assumptions is determined.

In the United States, the national policy for foot and mouth disease (FMD) vaccination lacks clarity. To better understand what potential Incident Commanders see as important 'triggers' or factors to consider for implementing vaccination as a control strategy, the authors presented seven such individuals with an FMD outbreak scenario that started in north-western Illinois and spread across state lines by the end of the fifth week. The scenario had four infected premises at the end of week one, 13 at the end of week two, and 60 (including both infected and previously depopulated premises) by the end of week five. Two individuals favoured vaccination the first week of the outbreak scenario, one did not want to vaccinate during the scenario, and the remainder wanted vaccination at some time during the scenario. Respondents ranked nine specific factors to take into consideration when deciding whether or not to vaccinate. Of these, the capability to manage the outbreak by stamping out ranked first. Many of the issues raised in this report are applicable to other countries that are currently FMD-free without vaccination.

To achieve further reductions in foodborne illness levels in humans, effective pre-harvest interventions are needed. The health status of food animals that are destined to enter the human food supply chain may be an important, although often overlooked, factor in predicting the risk of human foodborne infections. The health status of food animals can potentially influence foodborne pathogen levels in three ways. First, diseased animals may shed higher levels of foodborne pathogens. Second, animals that require further handling in the processing plant to remove affected parts may lead to increased microbial contamination and cross-contamination. Finally, certain animal illnesses may lead to a higher probability of mistakes in the processing plant, such as gastrointestinal ruptures, which would lead to increased microbial contamination and cross-contamination. Consequently, interventions that reduce the incidence of food animal illnesses might also help reduce bacterial contamination on meat, thereby reducing human illness. Some of these interventions, however, might also present a risk to human health. For example, the use of antibiotics in food animals can reduce rates of animal illness but can also select for antibiotic-resistant bacteria which can threaten human treatment options. In this study, we present a mathematical model to evaluate human health risks from foodborne pathogens associated with changes in animal illness. The model is designed so that potential human health risks and benefits from interventions such as the continued use of antibiotics in animal agriculture can be evaluated simultaneously. We applied the model to a hypothetical example of Campylobacter from chicken. In general, the model suggests that very minor perturbations in microbial loads on meat products could have relatively large impacts on human health, and consequently, small improvements in food animal health might result in significant reductions in human illness.

As the demand for food-supply veterinarians changes, while the level of expertise necessary in this field markedly increases, there is a need to examine alternative modalities for delivering food-supply veterinary education. It seems clear that not all veterinary schools in the United States can sustain optimally sized facilities for the broad-based training in all species of food animals that the current and future food-supply veterinarian needs. An alternative model is for select schools to establish consortial centers of excellence in specific food-animal species, to which students from other schools can go for optimum final-year education. This alternative mode of food supply-veterinary medical education is discussed here.

Economics seeks to understand and explain the allocation of resources within society and to suggest appropriate policy to achieve goals such as optimal efficiency. Relating antimicrobial use and antibiotic resistance is a complex task and requires very clear and careful analyses of many relationships. To address these relationships, antibiotic use data must be linked with other basic data. Ideally, a complex relational database needs to be developed. These must include data on: antimicrobial usage, farm-level animal productivity, basic disease, basic farm management, consumer response, and antimicrobial resistance at multiple levels (farm, during process, on a variety of both animal, vegetable and grain-derived food products, from humans, from other animal species, and from the environment) among other data. Such a complex relational database can help with the attribution and risk assessment process. Also these linked data are needed in order to develop the economic production models and other economic models, as well as control for confounding so that there is both adequate and appropriate statistical control. Antimicrobial usage data may become economically important for reasons unrelated to animal productivity and animal health. With expanding global trade of animals and animal products, there have been changes in restrictions and regulations associated with the movement of products. Future trade opportunities may be linked to antimicrobial usage. The European Union banned the use of antimicrobials for growth-promoting purposes based on perceived risk and on public opinion. Monitoring antimicrobial use, disease occurrence, and resistance patterns following changes in usage that are a result of either policy changes or response to new information will help in the understanding of the complex relationships in microbial and disease ecology. There is a lot of evidence substantiating the productivity and profitability gains to producers from the use of antimicrobials. There is also evidence for the potential gains to consumers, both from an economic perspective as well as from a health perspective. Economists can help identify the implications of these relationships both at a micro- and macro-economic level; both relative to producer and to consumer welfare. We are at a pivotal time in history with sufficient analytical expertise and tools to address this complex issue from a scientific perspective. Linking various agencies so there can be coordination of data collection and data sharing is needed to successfully address this topic.

This paper discusses how economic tools can be targeted and combined to enhance their usefulness in analyses of animal disease problems. It briefly reviews the most commonly used economic modelling techniques to clarify the applicability of specific economic methods to different problems in animal health analysis. The paper then reviews applications of these methods in the literature and suggests how further research could integrate and improve different economic approaches and link epidemiological and economic methods to address a wider range of issues at different scales of analysis.

This paper demonstrates how currently underutilised economic modelling techniques can enrich the analysis of animal disease problems. Increasingly, analyses of animal health programmes are expected to address a range of economic and social questions. These expectations can be addressed by better integration of epidemiological modelling with economic techniques whose application to animal health has not been thoroughly discussed in past reviews. This paper describes a range of economic models that can be applied in animal health research and provides guidance for determining the appropriate method given the issues at hand. The complexity of some of these approaches underlines the importance of multidisciplinary research and education.

Salmonellosis in humans is a costly disease traditionally assumed to be associated with exposure to contaminated food. We have developed a farm-to-fork model that allows estimation of the human health costs and risks associated with Salmonella in pork. This analysis focuses on the stages of the pork production chain up to the point of producing a chilled pork carcass. The model predicts the number of human cases of salmonellosis associated with pork (mean, 99,430; 90% confidence interval, 20,970 to 245,560) and the corresponding social costs (mean, $81.53 million; 90% confidence interval, $18.75 million to $197.44 million). Sensitivity and scenario analyses suggest that changes in Salmonella status during processing are more important for human health risk and have a higher benefit:cost ratio when compared with on-farm strategies for Salmonella control. Specifically, benefit:cost ratios are less than 1 (indicating they are not likely to be profitable from a social economic perspective) for the on-farm strategies of vaccination and meal feeding, whereas rinsing carcasses at various temperatures with and without sanitizer all have benefit:cost ratios greater than 1 (indicating they are profitable from a social economic perspective). This type of modeling is useful for evaluation of the relative cost effectiveness of interventions at different points in the food chain when allocating limited food safety dollars and is best used for examining trends and alternative strategies rather than for providing definitive dollar value estimates of risk. The dollar value estimates must be considered in the context of the wide confidence intervals.

Thirty swine production units in the midwestern United States were studied to assess the relationship of herd-level prevalence of Salmonella on the farm prior to slaughter versus at slaughter. Fecal samples were collected from 30 pigs on each farm within 48 h of slaughter, and 30 ileocecal lymph node samples were collected in the same shipment cohort at slaughter. Samples were cultured by conventional methods, and Salmonella identity was confirmed by serotyping. Overall, 11.7% (n = 105) of the fecal samples and 14.9% (n = 133) of the ileocecal lymph node samples were positive for Salmonella. Seventeen of the farms (56.7%) had one or more positive fecal samples, and 24 (80.0%) had one or more positive ileocecal lymph node samples. Twenty-four recognized serotypes and three additional distinct antigenic types were identified. Among all isolates, 56.5% had serotypes that were duplicated both on the farm and at slaughter for a particular cohort, whereas the remaining samples lacked a duplicate serotype in the other sample type. There was a positive correlation in the prevalence of Salmonella between fecal samples and ileocecal lymph node samples (Spearman's p = 0.75; 95% confidence interval [CI], 0.62 to 0.89). Linear regression analysis was used to identify two farms that biased the regression estimates. Excluding these farms, 62% of the variance in farm slaughter Salmonella prevalence was accounted for by on-farm prevalence. The analyses suggest that the prevalence of Salmonella spp. at slaughter can be predicted from preslaughter on-farm sampling and vice versa.

The effects of a single-dose Mycoplasma hyopneumoniae vaccine was studied in growing pigs. Each of 24 vaccinated cohorts of approximately 1200 pigs reared in separate barns was matched by time, farm site, and sex with unvaccinated cohorts. Pigs were naturally exposed to M. hyopneumoniae and porcine reproductive respiratory syndrome virus (PRRSv). Daily weight gain was 42 g per pig per day higher and mortality rate was 15.2/1000 pigs lower for vaccinated cohorts. Age at PRRSv onset was associated with mortality rate, but did not modify vaccine effects. M. hyopneumoniae vaccination was effective in promoting growth in spite of concurrent PRRSv infection.

Antimicrobial resistance is an issue of increasing global concern. Several investigators have suggested that antibiotic use in food-producing animals is a major contributor to the increasing incidence of antimicrobial-resistant organisms causing illness in humans (F. J. Angulo, K. R. Johnson, R. V. Tauxe, and M. L. Cohen, Microb. Drug Res. 6:77-83, 2000; P. D. Fey, T. J. Safranek, M. E. Rupp, E. F. Dunne, R. Efrain, P. C. Iwen, P. A. Bradford, F. J. Angulo, and S. H. Hinrichs, N. Engl. J. Med. 342:1242-1249, 2000; S. A. McEwen and P. J. Fedorka-Cray, Commun. Infect. Dis. 34(Suppl. 3):S93-S106, 2002; D. L. Smith, A. D. Harris, J. A. Johnson, E. K. Silbergeld, and J. G. Morris, Jr., Proc. Natl. Acad. Sci. USA 99:6434-6439, 2002; D. G. White, S. Zhao, R. Sudler, S. Ayers, S. Friedman, S. Chen, P. F. McDermott, D. D. Wagner, and J. Meng, N. Engl. J. Med. 345:1147-1154, 2001; W. Witte, Science 279:996, 1998). In this paper, we discuss this and other assumptions relevant to a quantitative risk assessment model for salmonellosis in humans. We also discuss other important aspects of modeling food safety and food-associated antimicrobial resistance risk to humans. We suggest that the role of food-producing animals in the origin and transmission of antimicrobial resistance and "foodborne" pathogens has been overestimated and overemphasized in the scientific literature; consequently, nonfoodborne transmission, including pet-associated human cases, has been underemphasized. Much evidence exists for the potential contribution to infectious disease that may be of human or pet origin (that may contact humans through food but not be of a food origin). Risk analyses that do not acknowledge the potential for these sources of cross-contamination will understate the contribution that origin has in the realm of foodborne and food-associated diseases (e.g., Salmonella) and the resulting uncertainty levels in the food system, thus leading to biased inferences. We emphasize the importance of evaluating both the foodborne and nonfoodborne transmission risk for salmonellosis and outline the basics of an analytical modeling approach in food safety with examples to illustrate strengths and limitations in the modeling. Examples illustrate, on a simplistic level, how varying assumptions and other inputs can influence the output of food-associated quantitative risk models.

A survey was distributed by mail to a random selection of Illinois pig farmers marketing 1,000 or more pigs in 1998 to assess their knowledge, attitude and behavior regarding on-farm food safety. Valid responses were received from 353 of the 946 surveys mailed (37.3%). Pork production accounted for more than 50% of gross agricultural revenues among 65.0% of respondents, and 91.2% were classified as "owner-operators." Knowledge of food-borne pathogens was mixed, with correct responses to questions as follows: Trichina, 80.4%; Salmonella, 58.5%; Toxoplasma, 19.9%; and Campylobacter, 12.8%. Producers strongly agreed that food safety was a shared responsibility at every level of the food chain, including the farm level, with an average score for all steps in the pork chain of 4.5 on a scale from 1 (not important) to 5 (very important). When asked whether third party verification of on-farm practices was important, 51.2% agreed and 48.8% either disagreed or neither agreed nor disagreed. Associations between demographic categories and knowledge of and attitudes toward food safety were detected for herd size, proportion of agricultural receipts from pig production, grower versus birth-to-market production, age categories, and whether the respondent owned the pigs or facilities. Many (53.4%) were willing to apply a suggested food safety practice, even if there was no net profit for the practice. Findings suggest that Illinois pork producers accept an important role in pork food safety and express a willingness to participate but have knowledge gaps that should be filled.

Objective: To compare serologic testing with slaughter evaluation in assessing effects of subclinical infection on average daily weight gain (ADG) in pigs., Design: Cohort study., Animals: 18 cohorts (30 to 35 pigs/cohort) of pigs on/farms., Procedure: Blood samples were collected, and pigs were weighed at 8, 16, and 24 weeks of age. Sera were tested for antibodies to porcine reproductive and respiratory syndrome virus (PRRSV), swine influenza virus (SIV), transmissible gastroenteritis virus (TGEV), pseudorabies virus, Mycoplasma hyopneumoniae, and Actinobacillus pleuropneumoniae. At slaughter, skin, nasal turbinates, lungs, and liver were examined. Associations between ADG and results of serologic testing and slaughter evaluation were examined by use of multiple linear regression., Results: Pathogens that had a significant effect on any given farm during any given year and the magnitude of that effect varied. However, at 16 and 24 weeks of age, a higher antibody titer was consistently associated with a lower ADG. Mean differences in ADG between seropositive and seronegative pigs were 18 g/d (0.04 lb/d) for SIV, 40 g/d (0.09 lb/d) for PRRSV, 38 g/d (0.08 lb/d) for M hyopneumoniae, and 116 g/d (0.26 lb/d) for TGEV. Of the evaluations performed at slaughter, only detection of lung lesions was consistently associated with a decrease in ADG., Conclusions and Clinical Relevance: Results suggest that subclinical infection with any of a variety of pathogens commonly found in swine herds was associated with a decrease in ADG. Serologic testing was more effective than slaughter evaluation in assessing the impact of subclinical infection on ADG in these pigs.

An epidemiologic model of pseudorabies virus (PRV) in swine was developed. This model was used to project future herd-to-herd disease transmission under alternative eradication or control programs over 20 years (1993 to 2012). With current PRV eradication program funding, it was projected that prevalence would be 23% in higher-risk states in the United States, 10% in moderate-risk states, and 1% in lower-risk states. Increased funding for the PRV eradication program was projected to reduce PRV prevalence substantially. Productivity and economic impacts of PRV also were estimated for the average size farrow-to-finish operation. These impacts included mortality for preweaning, nursery, growing/finishing, and breeding hogs; market weights and number of market hogs sold; farrowing rates, number of live pigs per litter, and number of litters per sow-year. Profitability was estimated to be $6/cwt less for PRV-infected herds than for uninfected herds. Aggregate effects of PRV eradication programs were estimated by use of economic welfare analysis. For all PRV eradication program alternatives analyzed, consumers were the major beneficiaries of the program because of reduced prices and increased consumption of pork. Estimates of the value of economic welfare impacts under the current program with an assumed parallel supply-curve shift were determined: consumers gained $336.5 million; producers gained $35.9 million; government expenditures were $197.1 million; and the benefit/cost ratio of the program was 1.89. Economic welfare measures were projected to increase substantially with increased PRV eradication program funding. Economic welfare measures also were estimated under other assumptions.

Supplementation of selenium and vitamin E to enhance disease resistance in dairy cattle has become common, particularly to prevent periparturient reproductive disorders and mastitis. To establish reference values for serum vitamin E and selenium concentrations in postparturient dairy cattle and to determine whether serum concentrations of these micronutrients varied with season and stage of lactation, cows from a stratified random sample of 50 herds were studied for 1 year. Blood samples were collected from each of the 50 study herds twice, from the 10 most recently parturient cows or from 10% of the herd, whichever was greatest. Mean concentration of vitamin E and selenium was 2.55 micrograms/ml and 78.12 ng/ml, respectively. Vitamin E concentrations were significantly (P < 0.05) higher during the summer and fall than during the winter and spring. Selenium concentrations were significantly (P < 0.05) lower during the summer and fall than during the winter and spring. Herd, season of blood sample collection, and time since parturition were significant (P < 0.02) in explaining variation in vitamin E and selenium concentrations.

Productivity and economic effects of pseudorabies were estimated for a mean-size, farrow-to-finish swine enterprise. A Delphi technique was used to elicit productivity effects from an expert panel. Enterprise budgets for pseudorabies-infected and noninfected herds were constructed by use of these productivity estimates, as well as by use of economic data from secondary sources. Data examined to determine effects on productivity included preweaning, nursery, and growing/finishing pig mortality; breeding hog mortality; feed conversion; labor; and veterinary services and medication expenses. Results indicated that profitability was lowered in infected herds by approximately $6/cwt of swine produced.

Epidemiologic modeling of the likely herd-to-herd transmission of pseudorabies virus (PRV) was developed to assess the progress and potential for the PRV-eradication program in the United States. The herd-to-herd transmission of PRV over a 20-year period (1993 to 2012) in the United States was simulated under various scenarios, which included variable program-funding levels and variable prevalences. A transition model (Markov process model) was used to predict yearly changes in herd prevalence of PRV infection. Five mutually exclusive states of nature for herds were assumed: uninfected and not vaccinated; uninfected and vaccinated; known to be infected and not vaccinated; known to be infected and vaccinated; and infected, but not known to be infected. Three prevalences for states in the United States were assumed: higher prevalence, moderate prevalence, and lower prevalence. Three funding levels were assumed: no eradication program, continued funding at the current level, and increased funding of 25%. Estimates made by an expert panel for determining probabilities in the state-transition matrices were used. A model also was developed, and was considered to be the most optimistic scenario likely under increased funding of 25%. The most optimistic estimates of the probabilities that still lay within the range of estimates made by the expert panel were used for this model. Only the optimistic transmission matrices allowed for total eradication of PRV.(ABSTRACT TRUNCATED AT 250 WORDS)

A stratified random sample of 50 Ohio dairy herds, monitored for 1 year between March 1988 and May 1989, was used to estimate the component costs of clinical mastitis per cow-year overall and by organism, the component costs of an episode of clinical mastitis overall and by organism, and the incidence of clinical mastitis by organism. Each herd was visited monthly by a veterinarian who conducted on-farm interviews and completed standardized data-collection forms designed to elicit economic information about the on-farm costs of clinical mastitis and mastitis prevention. Producers collected milk samples prior to treatment of clinical mastitis cases. Culturing methods allowed identification of 18 specific mastitis pathogen classifications. Annual costs estimated were on a per cow-year and clinical episode basis. The monthly mean population of cows monitored was 4,068. Mastitis prevention cost $14.50/cow-year, whereas the cost incurred by producers because of clinical cases of mastitis was $37.91. Organisms prevalent in the cows' environment caused the most costly types of mastitis. Disregarding contaminated samples and episodes for which no milk samples were taken, mastitis for which 2 organisms were isolated accounted for 35.5% of costs of clinical mastitis, followed by cases for which Escherichia coli (21.3%) was isolated, cases for which culturing yielded no growth (8.6%), and cases for which esculin-positive Streptococcus spp (6.4%), Klebsiella spp (5.7%), esculin-negative CAMP-negative Streptococcus spp (5.1%), Enterobacter spp (4.8%), coagulase-negative Staphylococcus spp (4.1%), coagulase-positive Staphylococcus spp (3.0%), S agalactiae (2.5%), and Bacillus spp (1.2%) were isolated.(ABSTRACT TRUNCATED AT 250 WORDS)

A cross-sectional study of 1,032 dairy herds in Ohio was conducted to determine the prevalence of the major contagious pathogens of mastitis (Streptococcus agalactiae and Staphylococcus aureus) and the use of common mastitis control measures. Herd owners were surveyed by mail concerning their use of mastitis control measures. The survey focused on treatment of nonlactating cows, postmilking teat dipping, culling practices, milking machine maintenance, treatment for clinical mastitis, and premilking hygiene practices. Nearly 90% of questionnaires were returned. The prevalence of Streptococcus agalactiae and Staphylococcus aureus was determined by use of bulk-tank milk samples. Most herds (n = 802) met the criteria for classification into 1 of 4 groups: (1) Free of contagious pathogens, as determined by inability to isolate coagulase positive staphylococci (CPS) and esculin-negative CAMP positive streptococci (ENCPS) from 3 bulk-tank milk samples, (2) CPS, but not ENCPS, isolated from at least 1 sample, (3) ENCPS, but not CPS, isolated from at least 1 sample, (4) both ENCPS and CPS isolated from at least 1 sample. The number of herds in which both ENCPS and CPS were isolated was low; therefore, these herds were grouped with herds in which ENCPS alone was isolated for the evaluation of mastitis control practices related to herd pathogen status. Herd somatic cell count (SCC) was determined using Dairy Herd Improvement Association data by calculating the geometric mean SCC from individual cow test day SCC. Twelve months of SCC data from 741 herds were included in this study.(ABSTRACT TRUNCATED AT 250 WORDS)

Various nutritious nutritional-supplement gels are being marketed for use in veterinary medicine. This study was designed to determine whether serum calcium, phosphorous, or magnesium concentrations were different between cows given a gel containing calcium chloride as its active ingredient (treated) and cows given inert carrier gel (control). The study revealed a significant (P < 0.01) increase in serum total calcium concentration within 5 minutes of administration of a calcium gel given to cows within 1 hour of parturition. Serum total calcium concentration had returned to baseline value by 24 hours after calcium gel administration. Serum inorganic phosphorus concentration also increased significantly (P < 0.05) after treatment. Significant changes in serum magnesium concentrations were not detected.

The value of the marginal product (VMP) for veterinary services and medical supplies (VETMED), and the profit maximizing level of VETMED were estimated for dairy producers. Data from the Pennsylvania Farmers Association-Dairy Farm Business Analysis system during the years of 1986 to 1990 were used to evaluate the functional relationship between production and expenditures for VETMED. Other input variables examined were man-year equivalents of labor, asset values, value of feed fed, and culling rate. Data were screened to reflect economically viable dairy farms in Pennsylvania, and 173 such farms participated for each of the 5 years analyzed. The VMP was estimated for 1990. Profit maximizing levels for VETMED were estimated for 1990 holding other input variables at their mean values. Mean expenditures for VETMED were $2,606/farm, or $43/cow in 1990. The VMP for VETMED was estimated to be $3.22 or $4.98, depending on the method of calculation. In other words, the marginal dollar spent on VETMED generated $3.22 ($4.98) in additional revenue from milk production. The profit maximizing level of expenditures for VETMED was $138/cow, substantially more than the mean, indicating the potential for farms in this data set to improve profitability through additional expenditures on VETMED.

Forty-eight herds participating in the 1988/1989 Ohio National Animal Health Monitoring System dairy project were monitored for 1 year to determine the effects of environment and management on mortality in preweaned calves. Environmental factors were evaluated by veterinarians during monthly visits to the herds. Management procedures were measured through the use of a questionnaire administered near the end of the project. Mortality in preweaned calves was calculated for each herd by using data from project records on calf mortality and animal inventory, which were collected monthly by veterinarians. Relationships between the management/environment variables and calf mortality were examined by use of analysis of covariance. Herd size, days on a nipple feeder, navel disinfection, type of housing, and whether each calf observed with diarrhea was treated with antibiotics were the variables that had an impact on herd mortality. These variables explained approximately 39% of the variation in mortality among herds.

To estimate herd prevalence of Salmonella spp, fecal specimens were obtained for culture from neonatal calves of 47 Ohio dairy herds. Of the 452 calves tested, 10 calves from 7 farms were culture-positive. Salmonella serotypes isolated were S dublin, S typhimurium, S enteritidis, S agona, S mbandaka, and S montevideo. Bulk tank milk filters from these dairies were also submitted for culture. Salmonella sp was isolated from 1 of the 50 filters, and 2 calves from this herd were found to be shedding Salmonella sp of the same serotype.

Dairy herds in Ohio were selected by stratified random sampling for participation in a disease-monitoring study to relate Streptococcus agalactiae intramammary prevalence to herd management and environmental conditions. Of 48 herds studied, 27 herds had at least 1 cow infected with this pathogen. Management and environmental conditions were assessed by direct observation as well as by an interview with the dairy producers. One-way ANOVA or chi 2 analysis, with presence or absence of Streptococcus agalactiae as the dependent variable, was used to test each of 70 independent variables. Variables found significant at P less than 0.20 were further evaluated by use of logistic regression. Our sample size permitted only 4 independent variables to be simultaneously evaluated by logistic regression. The most predictive risk factors were identified as poor teat and udder hygiene, poor environmental sanitation, large herd population, and use of a shared washcloth for premilking cleaning of teats and udders.

A hospital-based case-control study was conducted to evaluate and compare risk factors for abomasal volvulus (AV) and left displaced abomasum (LDA) in cattle. Medical record abstracts were derived from 17 North American veterinary schools by the Veterinary Medical Data Program for all cattle admitted between Jan 1, 1977 and Dec 31, 1986, and for those with a diagnosis of AV or LDA. From a total of 108,956 individual cattle records, 1,036 cases of AV and 7,695 cases of LDA were identified, with a ratio of LDA to AV cases of 7.4 to 1. In-hospital mortality was 23.5% for AV and 5.6% for LDA. Age, breed, gender, and season each had significant (P less than 0.05) effects on risk for AV and LDA. Risk for AV and LDA increased with increasing age, with greater risk in cattle aged 4 to 7 years. Dairy cattle were at higher risk of developing AV (adjusted odds ratio, 36.4) and LDA (adjusted odds ratio, 95.2) than were beef cattle. The odds of AV in Brown Swiss cattle were significantly (P less than 0.0001) lower, and the odds of LDA in Guernsey cattle were significantly (P less than 0.0001) higher than those in Holstein cattle. Female cattle were also at higher risk of developing AV (adjusted odds ratio, 3.3) and LDA (adjusted odds ratio, 29.1) than were male cattle. The odds of AV and LDA varied considerably throughout the year, with the lowest number of cases observed in autumn. Seasonal development of AV differed significantly (P less than 0.0001) from that of LDA, with the odds of AV and LDA being highest in January and March, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of pseudorabies in a commercial farrow-to-finish operation on selected production and economic values was estimated. Pseudorabies was first diagnosed in this herd by circle testing done in March 1988, as a required part of follow up from another herd that had been diagnosed with pseudorabies in the area. A pseudorabies virus vaccination program was initiated in the herd at that time. The mean litter size of pigs born alive varied from 9.26 to 10.02 pigs/litter throughout the study period; however, there was a twofold increase in suckling pig mortality and a 2.6-fold increase in nursery pig mortality when the months of the epizootic were compared with pre-epizootic months. In the 6-month period following the epizootic, suckling pig mortality was three-fold higher than that reported in the preepizootic months. Total net loss for this operation was estimated at $99,700 from when the epizootic started until eradication, when calculating losses directly. The major economic losses (76.5% of total loss) were related to suckling pig mortality, which was $16,240 during the epizootic or $24/inventoried sow/week; $19,395 in the 6 months following the epizootic or $3.8/inventoried sow/week; and $40,628 thereafter until eradication 26 months later or $0.37/inventoried sow/week. Nursery pig mortality losses were 12.6% of total net losses; $754 during the epizootic, $357 in the 6 months after the enzootic, and $11,444 thereafter until eradication 26 months later. Sow culling and deaths accounted for 9.4% of net losses that took place from 6 months after the epizootic until eradication.(ABSTRACT TRUNCATED AT 250 WORDS)

Forty-eight dairy herds in Ohio were selected as a stratified random sample for participation in a disease monitoring study to relate the prevalence of IMI with coliform and environmental streptococci to herd management and environmental conditions. Management and environmental conditions were assessed by farm inspection and by an interview with the dairy producers. A separate analysis for each independent variable identified many potential disease determinants. A multivariable analysis of a covariance model to predict the prevalence of coliforms had 6 model df (R2 = .47). Increased prevalence of coliform infection was associated with an increased amount of milk remaining in the udder after milking, use of free stalls, regular use of a running water wash, increased person hours per cow spent milking, and poor sanitation. The multivariable model for environmental streptococci used 5 model df (R2 = .51). Increased prevalence of environmental streptococci was associated with poor sanitation, increased number of days dry, use of tie stalls, no use of a shared wash cloth, and no use of an individual dry cloth.

Fecal samples were collected from 450 neonatal calves, ranging from 1 to 30 days old, between May, 1988 and May, 1989 to estimate the prevalence of bovine group A rotavirus in a stratified random sample of Ohio dairy herds. Calves were from 47 dairy herds chosen to be representative of Ohio herds. Bovine group A rotavirus was detected in fecal samples by a cell culture immunofluorescence test (CCIF) and ELISA. Of 450 samples tested, 46 (10%) were positive by CCIF and 67 (15%) were positive by ELISA. The agreement beyond chance between the 2 assays was good (kappa = 0.65). The overall prevalence rate of rotavirus shedding was 16.4% (74/450). Forty-three percent (29/67) of the samples positive by ELISA were subgroup 1, none were subgroup 2, and the remaining 57% (38/67) could not be assigned to either subgroups 1 or 2. Thirty herds (62.5%) had at least 1 group A rotavirus-positive calf (mean number of samples per positive herd = 12.4), and 17 herds (37.5%) had no rotavirus-positive calves (mean number of samples per negative herd = 6.0). A live oral rotacoronavirus vaccine was used in neonatal calves of only 1 herd and 3 of 17 (17.6%) calves from this herd were positive for group A rotavirus. The percentage of the rotavirus-positive fecal samples from all calves (n = 450) when stratified by fecal consistency was as follows: 28.3% (13/46) had liquid feces; 25.6% (10/39) had semiliquid feces; 23.4% (22/94) had pasty feces; and 10.7% (29/271) had firm feces.(ABSTRACT TRUNCATED AT 250 WORDS)

The use of a single bulk tank milk culture and a single milk filter culture was studied for their suitability as screening tests for coagulase-positive staphylococci and Streptococcus agalactiae . Bulk tank and bulk tank milk filter cultures were compared to quarter milk cultures taken from individual cows at 49 Ohio dairy herds selected from all Ohio dairy herds by a stratified random sampling scheme. Individual cow quarter milk samples were collected from a sample of all milking cows using a sampling scheme designed to detect an organism present in 2% of quarters, with 95% confidence intervals between 1 and 3%. Seventeen (35%) herds had one or more cows positive for S. agalactiae and 34 (69%) had one or more cows positive for coagulase-positive staphylococci. Using the results of individual cow sampling as the standard, the sensitivity for S. agalactiae was estimated as 23.5% for a single milk filter sample and 35.3% for a single bulk tank milk sample. The sensitivity for coagulase-positive staphylococci was estimated as 52.9% for a single milk filter culture and 41.2% for a single bulk tank milk culture. Based on these results and those of others, it appears that a single bulk tank or milk filter sample has a relatively low sensitivity for both coagulase-positive staphylococci and S. agalactiae , making these poor screening tests for the presence of these pathogens within a dairy herd.

Efforts to reduce the prevalence of Staphylococcus aureus intramammary infection were monitored in 3 Ohio dairy herds. Bacteriologic culturing of milk from all lactating cows in each herd was completed multiple times to identify infected cows and monitor reduction. Partial budgeting techniques were used to determine the economic outcome of the reduction program. Of particular emphasis was the economic impact of culling to maintain or achieve milk quality premium payments on the basis of bulk tank somatic cell counts. The prevalence of S aureusinfected cows was reduced in each herd. Culturing of milk from all lactating cows appeared to be an effective method to identify infected cows. Although numbers were limited, it also appeared that culturing of composite quarter samples was effective as a herd screening test to identify S aureus-infected cows. Bacteriologic culturing had a negative financial impact in all 3 herds. Using partial budgeting to assess the economic impact of the programs, it was determined that 2 herds experienced negative financial impacts as a result of an excess culling rate when compared with a 12-month baseline period prior to the initiation of the project. All herds had increased milk production per cow during the study as measured by the mature-equivalent method. However, when actual production was considered, increased milk production in each herd was not as great as that of other Ohio herds enrolled on Dairy Herd Improvement Association testing programs.(ABSTRACT TRUNCATED AT 250 WORDS)

Cows with three hundred and sixteen cases of clinical mastitis were sampled by microbiologic culture during a 6-mo period on a 1700-cow Michigan Holstein dairy farm. Daily milk weights were obtained on all cows before clinical onset and for 60 d after onset. Predicted post-mastitis production, projected on the basis of premastitis production and the lactation curves of contemporary non-mastitic herdmates, was compared with actual daily milk production during the 60 d following clinical onset. Cows experiencing clinical mastitis produced approximately 341 kg less salable milk during the 60 d after clinical onset compared with projected production. This milk loss included both decreased production and milk withheld from market following antibiotic treatment. Pluriparous cows lost 2.06 times as much milk as first lactation cows, and cows with mastitis occurring before 150 d in lactation lost 1.40 times as much milk when compared with other cows. Cows with mastitis occurring in the winter showed a milk loss 1.37 times greater than cows with mastitis in summer. The identity of the mastitis agent isolated from the clinical case was not strongly associated with the drop in milk production in the 60 d following clinical onset.

For efficient disease management in dairy production, the influence of disease prevention strategies on farm profitability must be known. A survey of mastitis control practices, milking machine function and maintenance, and cow environmental conditions was conducted with 406 dairy producers on the Michigan Dairy Herd Improvement-somatic cell counting program responding. These survey data, in conjunction with Dairy Herd Improvement production data, were used to develop a model estimating the marginal value products of mastitis control practices. Lost milk production associated with increased somatic cell count was calculated for each herd. Mastitis control practices, milking machine function and maintenance, and cow environmental conditions were used as independent variables in an analysis of covariance model with lost milk production as the dependent variable. Variables significant in explaining changes in production from increased somatic cell count were the use of teat dip, use of sanitizer in the wash water, milking cow bedding, summer nonlactating cow housing, summer calving locations, type of regulator, alternating pulsation, and rolling herd average milk production. The marginal value product (change in revenues received) from the use of iodine, chlorhexidine, and quaternary ammonium-type teat dips were $13.79, $16.09, and $22.17/cow/year, respectively, and these changes were statistically significant. However, sanitizer in the wash water was associated with a decrease in production. Management practices that have previously been shown to be economical and did not appear in the final model included nonlactating cow therapy and single-use paper towels.

The established association between milk production and SCC in dairy cattle is increasingly used to estimate lost production due to mastitis. Such cost estimates are used to make decisions regarding cost effective mastitis prevention and control. It is therefore important to verify the relationship between SCC and milk production using data from different areas of the country and by using different analytical methodology. Our study used the 1985 to 1986 Michigan DHIA data base and analyzed daily milk production records rather than lactation summary records as used in the past. One advantage to our approach was that it did not give equal weight to all lactations, regardless of their duration. Also, it enabled inclusion of cows that had incomplete lactations caused by culling, or had other reasons for removal from the herd. A statistical model was constructed to predict milk production on the basis of herd, cow within herd, stage in lactation, month of calving, lactation, and SCC. The data base contained 397,172 milk test records obtained from Michigan DHIA from 504 Holstein herds in Michigan's lower peninsula. Our final model predicted 78% of the variation in milk production. Prediction of milk loss for each herd was highly correlated (r = .98) with the prediction model adopted by most DHIA organizations. Our model predicted that the mean herd lost a mean of 1.17 kg of milk/cow per d associated with SCC.

A telephone survey was conducted of 50 randomly selected Ohio-licensed veterinarians engaged in dairy practice. The survey's purpose was to determine the extent of mastitis control services offered by practitioners and to assess their utilization of milk somatic cell count (SCC) data on individual cows available from the Dairy Herd Improvement Association (DHIA). During the preceding year, 96% (48/50) of practitioners surveyed had performed bacteriologic culture of milk samples. Practitioners were twice as likely to have performed culture on milk from mastitic cows that failed to respond to treatment as they were to have performed culture for purposes of identifying pathogen trends within a herd. Veterinarians in predominantly dairy practices were more likely to have completed bacteriologic examination of milk in their own laboratories than were veterinarians who were engaged in less than 50% dairy practice (P = 0.016). Most veterinarians (83%) reported that coagulase test results were available or that Staphylococcus aureus was differentiated from other staphylococcal species. Streptococcus agalactiae was not differentiated from other streptococcal species by 35% of practitioners surveyed. For veterinarians with clients enrolled in the DHIA, 91% (43/47) reported looking at, discussing, or otherwise using the DHIA records. Eighty-one percent (35/43) of veterinarians who had clients using services from the DHIA reported that clients also received individual cow milk SCC results. Veterinarians engaged in predominantly, dairy practice expressed a greater familiarity with the linear score method of SCC reporting than did veterinarians whose practices were less than 50% dairy (P = 0.085); however, both groups reported a preference for raw SCC data.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of pseudorabies in a 150-sow farrow-to-finish operation on selected production and economic values was estimated. Mean litter size remained the same throughout the observation period; however, there was a 2-fold increase in suckling pig mortality and a 3.5-fold increase in stillbirths when the months of the epizootic were compared with pre-epizootic months. Following the epizootic, suckling pig mortality was 13.7% greater (P less than 0.05) than that observed in the months preceding the epizootic, whereas stillbirth rate was 71% higher (P less than 0.01) than that reported in the pre-epizootic months. Total net loss for this operation was estimated at +48,175. The major economic losses (approximately 88% of the total loss) were related to breeding herd removal/repopulation and production downtime.

A telephone survey was conducted of 149 current recipients of the Ohio DHIA SCC option, 30 past recipients of the SCC option, and 30 producers who had never received the SCC option. Producers were questioned to ascertain their knowledge of mastitis, how they used SCC information, their treatment and prevention of mastitis, and their use of veterinary services. Producers' perceptions of mastitis indicated a high awareness of the consequences of mastitis. However, 10% of producers on DHI still did not practice postmilking teat dipping, and 16% did not handle mastitic cows any differently during milking. Current recipients of SCC data used the data more frequently than did past recipients of the SCC data to evaluate mastitis treatment or control, choose cows to cull, identify cows to dry off early, indicate herd infection, and evaluate mastitis control. The major reason given by nonrecipients for never having enrolled in the SCC program was that they did not perceive a need for it. Further educational programs explaining SCC and its use to producers seems warranted.

Data collected by the National Animal Health Monitoring System in Ohio for a 12-month period during 1986 and 1987 were used to determine the relative magnitude of costs associated with mastitis in the following categories: milk production loss, veterinary services, drugs, producer labor, and "other" factors. The cost of milk loss associated with mastitis that was reported by producers cooperating in the National Animal Health Monitoring System program was compared with estimates based on bulk tank somatic cell counts and individual cow milk somatic cell counts. Using producer-reported estimates, milk loss accounted for about one third of the total cost associated with mastitis. When estimates of milk loss were replaced by estimates based on bulk tank somatic cell counts, milk loss accounted for over 80% of the total cost of mastitis. Estimates of the cost of milk loss based on studies relating milk yield to somatic cell counts differed considerably. Consequently, it was unclear how to best estimate the relative magnitude of the milk loss component of mastitis costs.

Decreased feed efficiency and increased days to market often occur together causing an increase in production costs. By mathematical modeling, the effect of decreased feed efficiency on the growth of an animal is given and the resulting formulas for increased days to market are derived. The most general model discussed incorporates the effects on days to market weight of variable feed efficiency (above or below normal for that species) and weight loss with a subsequent growth set-back. The resulting predicted increased days to market compares well with experimental data and examples using published data are discussed. This modeling allows a good estimate of the increased costs of production due to finishing unthrifty animals, which takes into account all the variable daily costs, not just the increased total feed consumption during the period of growth to market weight.