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Biosecurity and herd health management practices on Canadian dairy farms
Abstract
The Canadian dairy industry has created national standards to support the adoption of biosecurity practices and to reduce disease risks across the country. There is, however, very little information on the adoption of these practices. The present study aimed to describe the adoption of biosecurity practices on Canadian dairy farms shortly after the creation of the national standards and to identify demographic factors associated with practice adoption. In 2015, 2 questionnaires (phase 1 and 2) were administered to Canadian dairy farmers during an extensive cross-sectional study. Associations between adoption of biosecurity practices as well as associations between adoption of these practices and demographic variables were tested using multiple correspondence analysis. A total of 1,157 questionnaires were completed in phase 1, and a subsample of 368 respondents was selected using stratified random sampling to complete phase 2 during visits to the farms. There was a lack of investigation into general disease syndromes such as a high prevalence of abortion or an unexplained death (38 and 22% of respondents, respectively). Biosecurity measures within herds and between herds to minimize the spread of infection were not widely adopted (e.g., 27% of the respondents never housed sick or lame animals in their calving pen, 41% had closed herds, and 25 and 48% of the open herds had no strategy for introducing new additions and reintroducing returning animals, respectively). Cleanliness of the cows before calving was always ensured by 29% of the respondents, and 27% of the respondents reported always sanitizing the calving pen after each calving. Less than 15% of the respondents had measures in place to limit or control visitors coming on their farm. Moreover, less than half of the respondents reported requiring family members, employees, and visitors to wear farm-designated or clean boots and coveralls. From the multiple correspondence analysis, 2 dimensions were retained and were summarized as "animal movement, calving area, and visitor biosecurity" and "employee biosecurity." Geographical region, type of housing, and milk production were associated with the "employee biosecurity" dimension. The present study demonstrates that many important biosecurity practices are not implemented on Canadian dairy farms; therefore, efforts to promote the adoption of these practices will be necessary to improve biosecurity in dairy herds.
... The segregation of sick animals can be considered a major component of on-farm disease prevention programs. In our study, 40% of the farmers reported keeping sick animals away from the rest of the herd, which is similar to Swedish dairy farmers (35-40% had a hospital pen; n = 198) [25], but much higher than Canadian dairy cattle farmers, of whom only 27% separated the lame and sick animals from the main herd (n = 1157) [26]. Additionally, it was reported that 40% of Wisconsin dairy farmers sell sick cows instead of culling them [12]. ...
... These researchers reported a lack of resources and inappropriate attitudes as the main reasons why these preventive measures were not implemented. By contrast, only a small proportion of Canadian dairy farmers (<5% of participants) used dead cattle as feed for carnivores (domesticated or wild) or left the body in the environment [26], while more than 90% asked a licensed professional (dead-stock collector) to collect and appropriately dispose of the cadavers. ...
... Borrowing tools from peers is a common practice among farmers across the world [26,41,42]. However, tools that have been contaminated by blood, mucus, or feces are an important source of disease transmission among and between farms [43]; hence, it is very important to clean and disinfect borrowed tools before using them [43,44]. ...
Preventing the spread of diseases between and within farms (biosecurity) is essential for minimizing animal mortality and morbidity, as well as for reducing the risk of spread of zoonotic diseases. These effects are even greater in countries such as Iran, which have to deal with multiple ongoing epidemics of infectious disease. However, there is currently no published information about biosecurity practices on sheep and goat farms in Iran in published research. The aim of this study was to collect such information and to identify some of the factors affecting biosecurity practices. Data were gathered using a checklist and in-depth interviews with 99 nomadic and semi-nomadic pastoralists. Regression analysis was used to identify the relationships between the collected variables and the biosecurity scores. The results showed that neither within- nor between-farm disease prevention measures were appropriately applied on most farms (median total score of total biosecurity was 37.3/90; Q1 = 29.0 and Q3 = 44.7). Almost all the farmers reported slaughtering animals on farms and nobody properly disposed of the bodies of the dead animals. Additionally, the majority of the participants did not disinfect the umbilical cords of newborns. Of the collected variables, the annual mortality rate was associated with most within-farm biosecurity practices. The increase in annual mortality rates was associated with the regular cleaning of troughs (p = 0.03), preventing feed and water from being contaminated by urine and feces (p = 0.02), providing a clean and dry place for animals to rest (p = 0.05) and disinfecting the navel cord (p = 0.03). The results of this survey suggest that there is a clear need for extension programs to enhance Iranian and sheep and goat farmers’ perceptions and practices regarding biosecurity measures.
... According to Leblanc et al., 75% of dairy cows that fall sick, fall sick in the first month postpartum, an interval where a series of hormonal and metabolic changes occur, making them highly susceptible to sickness [166]. (3) Biosecurity: It is crucial to prevent the introduction or spread of many multifactorial diseases within cows and within farms [180]. This control involves regular testing of the herd (serology, milk tank analyses, among others), quarantine and testing of purchased animals, hygiene and disinfection of spaces, and controlled visits to the farm, with the farm's own clothing [181]. ...
... Vaccination plans were introduced in dairy farms in 1970, to reduce the incidence and prevalence of various pathologies. Dairy farms with effective and strict vaccination programs have higher productivity, and better fertility indicators [180,[185][186][187]. It is in northern European countries that we see a greater adoption of vaccination and control protocols, with several national eradication programs successfully running. ...
This work aimed to review the important aspects of the dairy industry evolution at herd level, interrelating production with health management systems. Since the beginning of the industrialization of the dairy cattle sector (1950s), driven by the need to feed the rapidly growing urban areas, this industry has experienced several improvements, evolving in management and technology. These changes have been felt above all in the terms of milking, rearing, nutrition, reproductive management, and design of facilities. Shortage of labor, emphasis on increasing farm efficiency, and quality of life of the farmers were the driving factors for these changes. To achieve it, in many areas of the world, pasture production has been abandoned, moving to indoor production, which allows for greater nutritional and reproductive control of the animals. To keep pace with this paradigm in milk production, animal health management has also been improved. Prevention and biosecurity have become essential to control and prevent pathologies that cause great economic losses. As such, veterinary herd health management programs were created, allowing the management of health of the herd as a whole, through the common work of veterinarians and farmers. These programs address the farms holistically, from breeding to nutrition, from prevention to consultancy. In addition, farmers are now faced with a consumer more concerned on animal production, valuing certified products that respect animal health and welfare, as well as environmental sustainability.
... The influx of people, animals, and vehicles must be strictly controlled, and this is critical to preventing the introduction of pathogens to the area (BRENNAN & CHRISTLEY, 2012;DENIS-ROBICHAUD et al., 2019). Personnel not part of the staff should be prohibited, and eventual access by professional contractors and employees should be controlled. ...
... Clean and disinfected clothing and footwear must be provided to the staff and eventual visitors. Veterinarians and employees working on the property must change clothes and wear clean and work clothing during activities on the property, especially overalls and boots (BONATTI & MONTEIRO, 2008;DENIS-ROBICHAUD et al., 2019). Moreover, employees must be trained to correctly perform milking in order to maintain the quality of the milk, be aware of proper maintenance and cleaning of equipment, and be vigilant of possible changes in the teat and mammary gland of the animals (WILLIS et al., 2017). ...
The goat milk industry has unquestionably grown in recent years due to the high demand for dairy products, which are considered nutritious and hypoallergenic. As a result, security measures are required in the production chain to provide consumers with safe products, although the concept of biosecurity is still incipient in Brazilian goat farming. Therefore, this study aimed to review the main biosecurity measures applied to dairy goat farms and suggest a program that contemplates these measures to promote animal health and welfare, given that biosecurity bolsters environmental sustainability and improves this agricultural sector. Biosecurity programs (BP) are composed of a set of measures and procedures aimed at herd health and applied in all stages of animal husbandry, interacting with different sectors that make up the production system and providing a set of policies and operational norms to protect herds against potentially pathogenic agents. Thus, BP require planning, execution, monitoring, audits, updates, understanding of the procedures, and awareness of those involved in the production chain. In addition, it includes continuing education programs and the development of contingency plans for specific emergencies. The information included in this study provides input to dairy goat farms to implement practices that improve the productivity of this agricultural sector.
... The sampled farmers had a low level of information about endometritis diagnosis and management; hence, could not have applied some of the MIs on their farms. Recent studies conducted in Switzerland [46] and Canada [47] showed that farmers' awareness of the disease and a better understanding of the transmission of disease influence their perceptions on the effectiveness of biosecurity measures. Another study [48] with Indian farmers indicated that knowledge gaps about cattle diseases and how to prevent them limited the adoption of animal genetic improvement and health care practices. ...
... In Indonesia [49] and Ghana [50], studies concluded that insufficient VETs and lack of capital hindered farmers from accessing prompt veterinary services and adopting and implementing biosecurity measures. In Canada, a study indicated that farmers who discussed biosecurity measure with a VET were more likely to perceive biosecurity measure as more effective than farmers who did not [47]. This is an indication that it is the best practice that farmers regularly consult with the ANHS providers on a plan of dairy herd health management. ...
Background:
Endometritis is a prevalent uterine disease in postpartum cows. The disease reduces fertility performance and milk yield, and subsequently, productivity and profitability of dairy farms. The reduction in performance is associated with considerable economic losses on dairy farms. Smallholder farmers are likely to incur considerable economic losses from the disease where they lack knowledge of effective prevention and control measures for the disease. This study used farmer's perspectives to determine the effectiveness of different management interventions (MIs) for endometritis prevention and control on smallholder farms in Rwanda practicing dairy zero-grazing. The best-worst scaling (BWS) choice method was applied that relied on past 1 year recall data obtained from 154 farmers. These farmers were identified through snowball sampling in a cross-sectional study.
Results:
Of the 20 MIs evaluated, 12 scored highly for effectiveness. The top four most effective are: avoiding sharing equipment with neighbouring farms (45.5%), consulting animal health service provider about disease treatment (31.8%), keeping cows in a clean and dry shed (26.7%), and selecting sires based on calving ease (26.6%). The MIs considered least effective were: maintaining clean transition cow housing (35.1%), removal of fetal membrane immediately after passing (33.1%), disinfecting the equipment used in calving assistance before and after use (32.5%), and selecting sires with low percent stillbirths (29.2%).
Conclusion:
This study has demonstrated the application of BWS object case method in understanding the MIs that farmers consider are most effective in the prevention and control of endometritis disease in the dairy herds. The MIs are on-farm biosecurity and hygiene, seeking veterinary services for disease treatment and selecting sires for ease of calving. These MIs should be considered for prioritization in extension services and research to continuously improve and enhance their practical application on smallholder dairy farms.
... Therefore, it could be interesting to incorporate government veterinary services in future studies on biosecurity or related topics, as there is a tendency for farmers and veterinarians to question them, and this would give them the chance to share their own perspective. Better knowledge of all stakeholders' perspectives would also mean a better understanding of the psychosocial dynamics involved in such matters as heterogeneity in the routine implementation of biosecurity measures (9,(74)(75)(76). Furthermore, from a health perspective, stakeholders could also include public health professionals, especially in cases of zoonotic infectious diseases. ...
The implementation of biosecurity measures in livestock production systems can be affected by the psychosocial factors of its stakeholders, which can be observed through their knowledge, attitudes and perceptions/practices. In Spain, there are no regulations per se to promote biosecurity. Of all stakeholders, farmers and veterinarians have been addressed in previous biosecurity studies, but not veterinarians belonging specifically to the government services. This study explores this particular group’s perceptions of routine biosecurity in livestock production systems in north-western and north-eastern Spain, an understanding of which could help to improve the implementation of biosecurity measures on farms. Eleven interviews were conducted with veterinarians from different levels of the government services in Galicia and Catalonia, and were analysed through content analysis. Dairy cattle farms were considered as the reference livestock production systems. The respondents stress the limited availability of staff and time resources for biosecurity. The advisory role of government veterinarians is not well recognised among farmers, who feel that their services prioritise their sanctioning role. In fact, government veterinarians consider that farmers only implement biosecurity measures to avoid being sanctioned, and not because they are aware of the importance of biosecurity. Meanwhile, the participants comment that biosecurity regulations should be flexible and need to consider the contexts of the farms where biosecurity measures are implemented. Finally, government veterinarians are willing to attend biosecurity meetings together with all farm stakeholders, at which the government services could be informed about biosecurity issues on farms. The person who could take on the biosecurity advisory role should be defined, along with further discussion of such matters as the responsibilities of each stakeholder. Government veterinary services need to be considered in studies of biosecurity operations in order to improve their implementation. It is therefore concluded that government veterinarians are seeking to balance their own institutional perspective with that of farmers and veterinarians in the routine implementation of biosecurity measures.
... The percentage of explained variance (33.8%) in the present study is in-line with values found in similar works (Delpont et al., 2020;Denis-Robichaud et al., 2019). Values observed in multifactorial analyses are known to be lower than those found with principal component analysis, as in principal component analysis, only linear relationships are studied, whereas in multifactorial and clustering analyses, much more general relationships are studied (Husson et al., 2017). ...
The rapid intensification of the livestock sector in Southeast Asia has been found to be associated with an expanding use of antibiotics (ABU) and the rise of antimicrobial resistance (AMR) in both humans and livestock. This study aimed to explore the views and practices of commercial pig, poultry and fish farmers regarding antibiotics in Lao PDR, where data on antibiotic use and AMR remain scarce. A multistage cluster sampling method, based on the random selection of villages in two provinces of Vientiane, was used. A total of 364 farmers, corresponding to 454 farm units, were surveyed using a questionnaire and farm visits. This study found a widespread use of antibiotics (261 out of the 454 farm units used antibiotics). The predominance of antibiotics considered as critically important antibiotics for human medicine was of great concern. Results from a logistic regression model showed that antibiotics were found less frequently in fish farm units compared to pig and poultry farm units, and more frequently in specialized farms than in livestock‐fish farms. Multiple factor analysis and hierarchical cluster analysis revealed three profiles of farmers, each with distinct patterns on knowledge, attitudes and practices regarding ABU and AMR. Cluster 1 held a positive attitude regarding preventive measures and information about antibiotics. In cluster 2, there was a view that antibiotics should be used for prophylactic treatment such as disease prevention. Cluster 3 was characterized by farmers with weak knowledge who were unfamiliar with antibiotics and uncertain about details concerning antibiotic use. This cluster was associated with a significantly lower use of antibiotics than the two other clusters in the regression model. The results of this study may help the Laotian government to adapt strategies to control AMR by focusing on the use of critical antibiotics and prophylactic treatments and by tailoring measures to farmers’ profiles. This article is protected by copyright. All rights reserved
... Other on farm biosecurity management strategies include the reduction of interaction at wildlife-livestock interfaces. Recent studies have described the epidemiological relationships between wild and domestic species and concluded that wildlife presence within agricultural settings could promote the appearance of environmentally related diseases, such as the Mycobacterium tuberculosis complex and the persistence of Staphylococcus aureus [120][121][122][123][124]. Diseases and pathogens can also be transmitted through the various wild vectors including flies, ticks, rodents, mosquitoes [125]. ...
Farm biosecurity management includes a set of practical measures used to prevent and limit the spread of infections to humans and animals. Infections, predominantly caused by zoonotic agents, often occur due to a lack of safety standards monitoring on farms, but also because of the use of inappropriate antimicrobial products leading to bacterial resistance, tolerance to biocides and the emergence antimicrobial-resistant germs. To date, research was mainly focused on studying the antimicrobial resistance in bacterial biofilms and the mechanisms involved in their occurrence. At molecular level, the limited diffusion of biocides in the biofilm matrix, enzyme-mediated resistance, genetic adaptation, efflux pumps, and levels of metabolic activity inside the biofilm are some of the investigated biological mechanisms which can promote antimicrobial resistance in biofilms were also investigated. Interventions, based on the identification of novel antimicrobial compounds, that would exclude the occurrence of bacterial tolerance, including essential oils (oregano, cloves), organic acids (tannic & oleic acid) and natural plant compounds (e.g. alkaloids, flavonoids, tannins and coumarins) were also extensively studied and reviewed given their effectiveness against pathogen-produced biofilms. The aim of this review was emphasize the importance of biosecurity and farm management practices and to assess their impact on bacterial biofilm formation. Furthermore, we present the recent intervention strategies aimed at reducing and combating the formation of bacterial biofilms in livestock farms.
... The prevention of the introduction and spread of infectious diseases in animal production is the aim of management practices collectively termed biosecurity. Studies have shown biosecurity to be associated with reduced odds of diseases, improved productivity, and lower use of antimicrobials (8). Risks to the dairy industry can be reduced if dairy farmers proactively respond to specific changes, for instance, by stepping up their efforts to raise biosecurity and cut down the use of antimicrobials and hormones, while concurrently ensuring high standards of animal welfare (4). ...
Introduction
The aim of the study was to investigate the relationship between biosecurity as scored on the Italian National Animal Welfare Reference Centre (Centro di Referenza Nazionale per il Benessere Animale – CReNBA) checklist and the prevalence of Mycobacterium avium subsp. paratuberculosis , Chlamydophila abortus and Neospora caninum on dairy farms located in Ragusa, Italy.
Material and Methods
The checklist was used to assign an animal welfare score to 31 dairy farms. Twenty-one farms with a moderate score (>33%, <66%) formed group 1, and 10 farms with a high score (>66%) were group 2. Blood samples were collected from all cows on each farm to investigate the titres of antibodies against the relevant pathogens. Two-way analysis of variance was applied to assess differences between the two experimental groups and the Mann–Whitney test was applied to evaluate prevalence differences in the tested parasites between the groups.
Results
All tested farms had a score that classified them as either good or excellent. A higher incidence of Neospora caninum was observed in group 1. The incidences of the other two parasites were no different between the two groups.
Conclusion
The CReNBA checklist represents an impartial, reproducible, functional and smart instrument based on risk analysis and assigns a farm a mathematical animal welfare score. Among the parasites tested for, only Neospora caninum had prevalence influenced by biosecurity. Our preliminary results highlighted the positive associations between good animal welfare, high levels of biosecurity, and the prevention of the infectious diseases caused by the parasites in our focus, which are common on dairy farms.
... Despite this, only 38.5% of the respondent farmers (see Table S1) implemented quarantine measures when introducing animals. The movement of animals is the main cause of the spread of disease, and the introduction of new animals is a farm's highest risk of being infected with new diseases [55,56]. Moreover, important biosecurity practices, such as providing their own clothing to visitors or the use of footbaths, were not implemented at all in the farms surveyed on São Miguel Island. ...
The intensification of bovine milk production in the Azores has led farmers to increase farm size and specialization in grasslands, implementing confined and semi-confined production systems. Fixed milking parlours (FMP) have progressively gained more popularity, at the expense of conventional mobile milking systems (MMS). The present study aimed to evaluate the associations between production and health management in dairy cattle farms, with FMP or MMS, in grasslands (São Miguel, Azores), according to the farmers’ perspective. A total of 102 questions about production and health management were surveyed in 105 farms with >30 dairy cows each. Farms with FMP were associated (p ≤ 0.05) with larger herd size, better facilities, and specialized management, however, the adoption of preventive and biosecurity measures should be improved by these farmers. MMS farms implemented a lower level of disease prevention or control programs, less frequent transhumance, and showed a wider vocation to dual-purpose (milk and cross beef) than FMP farms. In conclusion, MMS and FMP farms tried to optimize yield and economic viability in different ways using grasslands. Several biosecurity and health prevention constraints were identified for improvement.
... Biosecurity is defined as the set of management practices implemented to avoid the introduction and spread of infectious diseases (1)(2)(3). Although it is clear that these practices have a beneficial impact on animal and herd heath, their adoption is relatively limited in dairy herds in Canada (4) and worldwide (5)(6)(7). To address this issue, the Canadian dairy industry has included biosecurity as one of the main pillars of the Canadian dairy producer Quality Assurance Program, the proAction initiative (8). ...
As part of the ProAction on-farm program to implement national biosecurity requirements on dairy farms, Canadian veterinarians are called upon to complete biosecurity risk assessments. The objective of the present study was consequently to understand veterinarians' perceptions of biosecurity, and to compare perceptions among producer-veterinarian pairs. Questionnaires were administered to 106 producers from Quebec and their veterinarians (n = 82), and the answers of the producer-veterinarian pairs were compared. While most veterinarians reported it was easy to discuss biosecurity with their clients, most veterinarians and producers did not report discussing biosecurity. Moreover, when producers or veterinarians reported discussing biosecurity topics, there was no agreement amongst pairs. Veterinarians also misjudged how their clients perceived the importance and usefulness of biosecurity. Finally, veterinarians reported they had the knowledge and opportunity to assess and discuss biosecurity on dairy farms but lacked skills for evaluating farms and communicating their knowledge.
Previous research has demonstrated that static monthly networks of between-herd dairy cow movements in Ontario, Canada were highly fragmented, reducing potential for large-scale outbreaks. Extrapolating results from static networks can become problematic for diseases with an incubation period that exceeds the timescale of the network. The objectives of this research were to: 1) describe the networks of dairy cow movements in Ontario, and 2) describe the changes that occur among network analysis metrics when conducted at seven different timescales. Networks of dairy cow movements were created using Lactanet Canada milk recording data collected in Ontario between 2009 and 2018. Centrality and cohesion metrics were calculated after aggregating the data at seven timescales: weekly, monthly, semi-annual, annual, biennial, quinquennial, and decennial. There were 50,598 individual cows moved between Lactanet-enrolled farms, representing approximately 75% of provincially registered dairy herds. Most movements occurred over short distances (median = 39.18 km), with fewer long-range movements (maximum = 1150.80 km). The number of arcs increased marginally relative to the number of nodes with longer network timescales. Both mean out-degree, and mean clustering coefficients increased disproportionately with increasing timescale. Conversely, mean network density decreased with increasing timescale. The largest weak and strong components at the monthly timescale were small relative to the full network (267 and 4 nodes), whereas yearly networks had much higher values (2213 and 111 nodes). Higher relative connectivity in networks with longer timescales suggests pathogens with long incubation periods and animals with subclinical infection present increased potential for wide-spread disease transmission among dairy farms in Ontario. Careful consideration of disease-specific dynamics should be made when using static networks to model disease transmission among dairy cow populations.
On-farm euthanasia is complicated in that farmers have to make the decision to end the life of an animal they are caring for. Studies have shown that some culling decisions are made too late, which results in animal welfare issues. However, information about on-farm euthanasia methods and the decision process leading to the euthanasia of an animal is limited. Additionally, emotions and feelings are involved in the decision and the act of euthanasia. The objectives of this study were to describe current practices related to on-farm euthanasia performed by Canadian dairy farmers and to assess the emotions and complex feelings surrounding the act. A cross-sectional study design was used to gather this information through an online questionnaire completed exclusively by Canadian dairy farmers. Data were analyzed descriptively using frequencies, and associations between the participants' characteristics and their practices and emotions regarding on-farm euthanasia were assessed using logistic regression models. A total of 479 dairy farmers from 5 provinces answered the survey. The most commonly used primary method of on-farm euthanasia was a firearm (>70%). Unacceptable euthanasia methods, such as standard 0.22-caliber long rifle for adult cows or no adjunct method following the use of captive bolt, were used by 25%, 18%, and 58% of the participants for calves, replacement animals, and dairy cows, respectively. Ninety-four percent of the participants reported that the farm owner was the person who always or often made the euthanasia decisions. In addition, 32% of the participants reported that the veterinarian always examined the animal before performing euthanasia, 51% reported at least one person received training to perform euthanasia, and 16% reported having a decision tree for euthanasia. Some participants (17%) were troubled with the responsibility for ending the life of their animals, and 19% perceived other people on the farm to be uncomfortable with performing euthanasia. Half of the participants reported that people performing euthanasia on the farm felt at least one related painful emotion or complex feeling, and half reported they had at least one reason to feel anxiety or unease concerning euthanasia. The results of this study showed gaps such as the limited use of acceptable euthanasia methods and decision trees by Canadian dairy farmers, low availability of on-farm training for euthanasia, and variable involvement of veterinarians.
The objective of this cross-sectional study was to evaluate the presence of infectious disease in newly arrived cattle on dairy farms in Ontario. Cattle that were more than 2 years old and arrived at dairy farms within the previous year were tested. A total 321 cattle from 56 dairy farms were sampled and had blood submitted to a diagnostic laboratory. Of all sampled cattle, 0.0%, 39.6%, 2.2%, and 1.3% tested positive for Anaplasma, bovine leukemia virus, Mycobacterium avium subsp. paratuberculosis, and Salmonella Dublin, respectively. Based on these results, it is imperative that dairy producers are vigilant to ensure they do not purchase animals with these important and untreatable infectious diseases.
A survey was conducted to investigate potential differences in biosecurity and health management practices on Irish dairy farms that sent their heifers for contract-rearing (source dairy farms, SDF; n = 62) and those rearing their own heifers (control farms, CF; n = 50). Participating farmers were surveyed by postal questionnaire between September and November 2018. The overall response rate was 93%. Results show that structurally, SDF were larger, less fragmented, and more specialized than CF. Outsourcing of labor-intensive activities to external contractors was more common among SDF than CF, exposing them to potentially increased biosecurity risks associated with animal movements, use of shared equipment, and increased frequency of farm visitors. The majority of SDF sent heifers to a single-origin rearing facility (70%), with heifers most commonly arriving at the rearing unit between 2 and 4 mo (53%) and returning to the dairy farm between 18 and 21 mo of age (56%). Despite the increased biosecurity risk associated with contract-rearing, implementation of disease prevention measures was not superior on SDF compared with CF. For both farm types, there was scope for improvement to visitor biosecurity protocols, quarantine procedures, colostrum feeding practices, and hygiene of calving areas. This research provides an overview of the demographics and farm management practices implemented by dairy farmers engaged in contract-rearing of replacement heifers, and will serve to inform farmers, veterinary advisors, and policy makers.
The impact of Covid-19 pandemic disrupts the supply chain for livestock breeds, feed, medicines, and others interfere sustainability of livestock businesses. This study aimed to determine the dairy cattle business’s changes during the pandemic at Business Group (KUB) Tirtasari Kresna Gemilang, Malang Regency, Indonesia. The data were obtained using the purposive sampling method. Respondents consisted of 17 dairy farmers (10%) of the total KUB members. The results showed that the farmer had been farming for 10-30 years with a population of three to eight cows. The average milk production of a cow can be maintained at 20 liters/head/day. Cows were given forage and concentrate (made by KUB) two to four times a day. The total cost of feed per month has not changed, which is around IDR 500,000 to IDR 3,000,000. The selling price of milk is IDR 5,400 before and during the pandemic. Health management methods include routine sanitation, injection vitamins, pre-dipping with warm water, and post-dipping with iodine. From this study can be concluded that the farmer of KUB Tirtasari Kresna Gemilang can survive with their management and farming experience, so they were able to sustain and have no problems with their business during the pandemic.
Regular veterinary visits to improve herd health and production management (HHPM) are important management components on many dairy cattle farms. These visits provide opportunities for constructive conversations between veterinarians and farmers and for shifting management from a reactionary approach to proactively optimizing health and welfare. However, little is known about the structure of HHPM farm visits and to what extent veterinarians provide assistance beyond purely technical services. Therefore, our aims in this cross-sectional study were to describe HHPM farm visit structure, determine which dairy-specific topics were discussed, and assess whether the focus of the visits aligned with farmers' priorities. Veterinary practitioners (n = 14) were recruited to record audio and video of regularly scheduled HHPM farm visits (n = 70) using an action camera attached to their chest or head. A questionnaire was distributed to farmers containing closed- and open-ended questions to assess their goals and perceptions related to farm management and HHPM farm visits. Descriptive statistics and negative binomial and Poisson regression models were used to study dairy-specific topics initiated by the farmer or veterinarian during various activities. A mean of 51% of the visit duration was dedicated to transrectal pregnancy and fertility diagnostics, and a considerable amount of time (30%) was spent on visit preparation, transitions between tasks, and leaving. A total of 488 discussions were initiated by either the veterinarian (55%) or the farmer (45%). Mean length of discussions was 2 min, and only 17% of the HHPM visit duration was spent discussing dairy-specific topics. Veterinarians initiated 62% of their discussions about herd issues, whereas farmer-initiated discussions revolved around herd health in 39% of the discussions. Discussion topics most frequently raised by participants included fertility, udder health, calf health and management, and transition diseases. Consistently, farmers' answers to a rank question regarding their main HHPM farm visit goals indicated that their priorities were to have transrectal pregnancy and fertility diagnostics performed and to improve herd fertility and general herd health. Answers to an open-ended question revealed that additional aims of many farmers were to receive information, have questions answered, and identify and discuss problems. A farmer's belief that HHPM farm visits were "absolutely" tailored toward his or her goals was positively associated with number of discussions during the visit and their conviction that they "always" voiced their wishes and needs to the veterinarian. Opportunities to broaden the focus of HHPM farm visits and improve communication between farmers and veterinarians should be identified and veterinarians should be trained accordingly, which would increase veterinarians' ability to add value during HHPM farm visits.
Background
Good animal health is a notion that is germane to organic dairy production, and it is expected that such herds would pay significant attention on the health of their animals. However, it is not known if the applied animal disease management is actually more adequate in organic dairy cattle herds than in conventional dairy herds. A questionnaire study on biosecurity and animal disease management activities was therefore conducted among Swedish farmers with organic and conventional dairy cattle herds.
Results
A total of 192 useable questionnaires were returned; response rates of 30.3 and 20.2% for organic and conventional farmers, respectively. Herd characteristics of the two herd types were very similar, except that pipeline/tie-stall systems were less common in organic farms and that organic farmers had a higher education level than their conventional counterparts. Also, very few systematic differences in general or specific disease management activities were observed between the two types of farms. The main exceptions being how milk from cows during antibiotic treatment was used, views on policy actions in relation to antibiotic use, and attitudes towards calling for veterinary support. Using milk from cows during antibiotic treatment was more common in conventional herds, although it was mainly given to bull calves. Farmers of organic herds were more positive to policy actions to reduce the use and need for antibiotics, and they reported waiting longer before contacting a veterinarian for calves with diarrhoea and cows with subclinical mastitis.
Conclusions
The stated biosecurity and animal disease management was relatively equal in Swedish organic and conventional dairy herds. Our results thus indicate that animal health is as important in conventionally managed dairy herds in Sweden as in organically managed herds.
Infectious diseases in livestock can be transmitted through fomites: objects able to convey infectious agents. Between-farm spread of infections through fomites is mostly due to indirect contacts generated by on-farm visits of personnel that can carry pathogens on their clothes, equipment, or vehicles. However, data on farm visitors are often difficult to obtain because of the heterogeneity of their nature and privacy issues. Thus, models simulating disease spread between farms usually rely on strong assumptions about the contribution of indirect contacts on infection spread. By using data on veterinarian on-farm visits in a dairy farm system, we built a simple simulation model to assess the role of indirect contacts on epidemic dynamics compared to cattle movements (i.e. direct contacts). We showed that including in the simulation model only specific subsets of the information available on indirect contacts could lead to outputs widely different from those obtained with the full-information model. Then, we provided a simple preferential attachment algorithm based on the probability to observe consecutive on-farm visits from the same operator that allows overcoming the information gaps. Our results suggest the importance of detailed data and a deeper understanding of visit dynamics for the prevention and control of livestock diseases.
Biosecurity, defined as a series of measures aiming to stop disease-causing agents entering or leaving an area where farm animals are present, is very important for the continuing economic viability of the United Kingdom dairy sector, and for animal welfare. This study gathered expert opinion from farmers, veterinarians, consultants, academics, and government and industry representatives on the practicality and effectiveness of different biosecurity measures on dairy farms. The study used best-worst scaling, a technique that allows for greater discrimination between choices and avoids the variability in interpretation associated with other methods, such as Likert scales and ranking methods. Keeping a closed herd was rated as the most effective measure overall, and maintaining regular contact with the veterinarian was the most practical measure. Measures relating to knowledge, planning, and veterinary involvement; buying-in practices; and quarantine and treatment scored highly for effectiveness overall. Measures relating to visitors, equipment, pest control, and hygiene scored much lower for effectiveness. Overall, measures relating to direct animal-to-animal contact scored much higher for effectiveness than measures relating to indirect disease transmission. Some of the most effective measures were also rated as the least practical, such as keeping a closed herd and avoiding nose-to-nose contact between contiguous animals, suggesting that real barriers exist for farmers when implementing biosecurity measures on dairy farms. We observed heterogeneity in expert opinion on biosecurity measures; for example, veterinarians rated the effectiveness of consulting the veterinarian on biosecurity significantly more highly than dairy farmers, suggesting a greater need for veterinarians to promote their services on-farm. Still, both groups rated it as a practical measure, suggesting that the farmer-veterinarian relationship holds some advantages for the promotion of biosecurity.
Biosecurity is crucial for safeguarding livestock from infectious diseases. Despite the plethora of biosecurity recommendations, published scientific evidence on the effectiveness of individual biosecurity measures is limited. The objective of this study was to assess the perception of Swiss experts about the effectiveness and importance of individual on-farm biosecurity measures for cattle and swine farms (31 and 30 measures, respectively). Using a modified Delphi method, 16 Swiss livestock disease specialists (8 for each species) were interviewed. The experts were asked to rank biosecurity measures that were written on cards, by allocating a score from 0 (lowest) to 5 (highest). Experts ranked biosecurity measures based on their importance related to Swiss legislation, feasibility, as well as the effort required for implementation and the benefit of each biosecurity measure. The experts also ranked biosecurity measures based on their effectiveness in preventing an infectious agent from entering and spreading on a farm, solely based on transmission characteristics of specific pathogens. The pathogens considered by cattle experts were those causing Bluetongue (BT), Bovine Viral Diarrhea (BVD), Foot and Mouth Disease (FMD) and Infectious Bovine Rhinotracheitis (IBR). Swine experts expressed their opinion on the pathogens causing African Swine Fever (ASF), Enzootic Pneumonia (EP), Porcine Reproductive and Respiratory Syndrome (PRRS), as well as FMD. For cattle farms, biosecurity measures that improve disease awareness of farmers were ranked as both most important and most effective. For swine farms, the most important and effective measures identified were those related to animal movements. Among all single measures evaluated, education of farmers was perceived by the experts to be the most important and effective for protecting both Swiss cattle and swine farms from disease. The findings of this study provide an important basis for recommendation to farmers and policy makers.
The dairy industry in the developed world has undergone profound changes over recent decades. In this paper, we present an overview of some of the most important recent changes in the dairy industry that affect health and welfare of dairy cows, as well as the science associated with these changes. Additionally, knowledge gaps are identified where research is needed to guide the dairy industry through changes that are occurring now or that we expect will occur in the future. The number of farms has decreased considerably, whereas herd size has increased. As a result, an increasing number of dairy farms depend on hired (nonfamily) labor. Regular professional communication and establishment of farm-specific protocols are essential to minimize human errors and ensure consistency of practices. Average milk production per cow has increased, partly because of improvements in nutrition and management but also because of genetic selection for milk production. Adoption of new technologies (e.g., automated calf feeders, cow activity monitors, and automated milking systems) is accelerating. However, utilization of the data and action lists that these systems generate for health and welfare of livestock is still largely unrealized, and more training of dairy farmers, their employees, and their advisors is necessary. Concurrently, to remain competitive and to preserve their social license to operate, farmers are increasingly required to adopt increased standards for food safety and biosecurity, become less reliant on the use of antimicrobials and hormones, and provide assurances regarding animal welfare. Partly because of increasing herd size but also in response to animal welfare regulations in some countries, the proportion of dairy herds housed in tiestalls has decreased considerably. Although in some countries access to pasture is regulated, in countries that traditionally practiced seasonal grazing, fewer farmers let their dairy cows graze in the summer. The proportion of organic dairy farms has increased globally and, given the pressure to decrease the use of antimicrobials and hormones, conventional farms may be able to learn from well-managed organic farms. The possibilities of using milk for disease diagnostics and monitoring are considerable, and dairy herd improvement associations will continue to expand the number of tests offered to diagnose diseases and pregnancy. Genetic and genomic selection for increased resistance to disease offers substantial potential but requires collection of additional phenotypic data. There is every expectation that changes in the dairy industry will be further accentuated and additional novel technologies and different management practices will be adopted in the future.
Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
Antimicrobials are frequently used for treatment of bovine mastitis and few studies have examined modern treatment strategies on large US dairy farms. The objective of this study was to describe treatment practices for clinical mastitis occurring in cows on large dairy herds in Wisconsin. Treatments performed on 747 cows experiencing cases of mild, moderate, or severe symptoms of clinical mastitis were recorded on 51 Wisconsin dairy farms. Duplicate milk samples were collected from the affected quarter for microbiological analysis at the onset of clinical mastitis and 14 to 21 d after treatment ended. Cows were treated according to individual farm protocol. Drugs and doses used for treatments were recorded for each case. Among all herds, 5 intramammary (IMM) antimicrobials (amoxicillin, hetacillin, pirlimycin, ceftiofur, and cephapirin) were used to treat cows for clinical mastitis. Of 712 cows with complete treatment data, 71.6% were treated with IMM ceftiofur either solely or combined with other antimicrobials (administered either IMM or systemically). Of cows experiencing severe symptoms of clinical mastitis, 43.8% received IMM treatment concurrent with systemic antimicrobials. Of all cows treated, 23.1% received an additional secondary treatment (either IMM, systemic, or both) because of perceived lack of response to the initial treatment. The majority of IMM treatments were administered to cows with a microbiological diagnosis of no growth (34.9%) or Escherichia coli (27.2%). Half of the cows experiencing cases caused by E. coli were treated using systemic antimicrobials in contrast to only 6.8% of cows experiencing cases caused by coagulase-negative staphylococci. In conflict with FDA regulations, which do not allow extra-label treatments using sulfonamides, a total of 22 cows from 8 farms were treated with systemic sulfadimethoxine either solely or in combination with oxytetracycline. Antimicrobial drugs were used on all herds and many cows received extra-label treatments. Great opportunity exists to improve mastitis therapy on large dairy herds, but use of more diagnostic methodologies is necessary to guide treatments. Farmers and veterinarians should work together to create protocols based on the herd needs considering reduced inappropriate and excessive use of antimicrobials.
In addition to livestock movements, other between-farm contacts such as visitors may contribute to the spread of contagious animal diseases. Knowledge about such contacts is essential for contingency planning. Preventive measures, risk-based surveillance and contact tracing may be facilitated if the frequency and type of between-farm contacts can be assessed for different types of farms. The aim of this study was to investigate the frequency and types of visitors on farms with cloven-hoofed animals in Sweden and to analyse whether there were differences in the number of visitors attributable to region, season, and type of herd. Data were collected from Swedish farmers through contact-logs covering two-week periods during four different seasons.
In total, 482 (32%) farmers filled in the contact log for at least one period and the data represent 18,416 days. The average number of professional and non-professional visitors per day was 0.3 and 0.8, respectively. Whereas the number of professional visitors seemed to increase with increasing herd size, this relation was not seen for non-professional visits. The mean numbers of visitors per day were highest in the summer and in the farm category 'small mixed farm'. Reports of the visitors' degree of contact with the animals showed that veterinarians, AI-technicians, animal transporters and neighbours were often in direct contact with the animals or entered the stables and 8.8% of the repairmen were also in direct contact with animals, which was unexpected. In a multivariable analysis, species, herd size and season were significantly associated with the number of professional visitors as well as the number of visitors in direct contact with the animals.
In conclusion there was a large variation between farms in the number and type of contacts. The number of visitors that may be more likely to spread diseases between farms was associated with animal species and herd size.
A common approach to deal with missing values in multivariate exploratory data analysis consists in minimizing the loss function over all non-missing elements, which can be achieved by EM-type algorithms where an iterative imputation of the missing values is performed during the estimation of the axes and components. This paper proposes such an algorithm, named iterative multiple correspondence analysis, to handle missing values in multiple correspondence analysis (MCA). The algorithm, based on an iterative PCA algorithm, is described and its properties are studied. We point out the overfitting problem and propose a regularized version of the algorithm to overcome this major issue. Finally, performances of the regularized iterative MCA algorithm (implemented in the R-package named missMDA) are assessed from both simulations and a real dataset. Results are promising with respect to other methods such as the missing-data passive modified margin method, an adaptation of the missing passive method used in Gifi’s Homogeneity analysis framework.
Few studies have considered in detail the range of biosecurity practices undertaken on cattle farms, particularly within the UK. In this study, 56 cattle farmers in a 100 km² area of north-west England were questioned regarding their on-farm biosecurity practices, including those relating to animal movements, equipment sharing and companies and contractors visiting the farms.
There was great variation between farms in terms of the type of, and extent to which, biosecurity was carried out. For example, the majority of farmers did not isolate stock bought onto the farm, but a small proportion always isolated stock. Many farmers administered treatments post-movement, primarily vaccinations and anthelmintics, but very few farms reported carrying out any health checks after moving animals on. In addition, there appeared to be much variation in the amount of biosecurity carried out by the different companies and contractors visiting the farms. Deadstock collectors and contracted animal waste spreaders, although likely to have a high potential for contact with infectious agents, were reported to infrequently disinfect themselves and their vehicles.
These findings suggest that although certain biosecurity practices are undertaken, many are carried out infrequently or not at all. This may be due to many factors, including cost (in time and money), lack of proven efficacies of practices and lack of relevant education of veterinary surgeons, producers and other herd health specialists. Further research exploring the reasons for the lack of uptake is imperative if preventive medicine is to be utilised fully by the farming industry.
To implement biosecurity measures at farm-level is a motivational challenge to dairy farmers as emerging diseases and their consequences largely are unpredictable. One of the reasons for this challenge is that outcomes are more likely to benefit society than the individual farmer. From the individual farmer's point of view the impacts of zoonotic risk, international trade and welfare concerns appear less obvious than the direct costs at farm-level. Consequently, a social dilemma may arise where collective interests are at odds with private interests. To improve biosecurity at farm-level farmers must be motivated to change behavior in the 'right' direction which could provide selfish farmers with unintended possibilities to exploit the level of biosecurity provided by other dairy farmers' collective actions. Farmers' perception of risk of disease introduction into a dairy herd was explored by means of Q-methodology. Participating farmers owned very large dairy herds and were selected for this study because Danish legislation since 2008 has required that larger farms develop and implement a farm specific biosecurity plan. However, a year from introduction of this requirement, none of the participating farmers had developed a biosecurity plan. Farmers' perception of biosecurity could meaningfully be described by four families of perspectives, labeled: cooperatives; confused; defectors, and introvert. Interestingly, all families of perspectives agreed that sourcing of animals from established dealers represented the highest risk to biosecurity at farm-level. Farmers and policy-makers are faced with important questions about biosecurity at farm-level related to the sanctioning system within the contextual framework of social dilemmas. To solve these challenges we propose the development of a market-mediated system to (1) reduce the risk of free-riders, and (2) provide farmers with incentives to improve biosecurity at farm-level.
For 20 years, bovine tuberculosis (BTB) has been spreading in Great Britain (England, Wales and Scotland) and is now endemic in the southwest and parts of central England and in southwest Wales, and occurs sporadically elsewhere. Although its transmission pathways remain poorly understood, the disease's distribution was previously modelled statistically by using environmental variables and measures of their seasonality. Movements of infected animals have long been considered a critical factor in the spread of livestock diseases, as reflected in strict import/export regulations, the extensive movement restrictions imposed during the 2001 foot-and-mouth disease outbreak, the tracing procedures after a new case of BTB has been confirmed and the Government's recently published strategic framework for the sustainable control on BTB. Since January 2001 it has been mandatory for stock-keepers in Great Britain to notify the British Cattle Movement Service of all cattle births, movements and deaths. Here we show that movements as recorded in the Cattle Tracing System data archive, and particularly those from areas where BTB is reported, consistently outperform environmental, topographic and other anthropogenic variables as the main predictor of disease occurrence. Simulation distribution models for 2002 and 2003, incorporating all predictor categories, are presented and used to project distributions for 2004 and 2005.
A survey of Southland farms was conducted to assess the potential for foot-and-mouth disease dissemination through normal movement patterns of farm animals and materials over a period similar to what would be expected from the time the virus arrived on a property to the time of diagnosis. Each farmer participating in the survey was required to complete a diary, recording all movements of people, animals and materials on to or off a farm during a 14-day period. The mean number of movements recorded per farm was 50. The distribution of movement distances showed the majority of movements occurred within the immediate neighbourhood of the origin, with 31.5% and 59.5% of all movements occurring within 5 km and 10 km respectively. In order to contain 95% of all movements, an area where movement was controlled would have to have a radius of 100 km. The data was then used to construct a spatial simulation model to study the movements off a hypothetical index farm. When secondary movements off primary destinations were included in the model, the mean number of movements to be traced to contain the disease was 100 (range 77-160) for a 14-day simulation period. The area required to contain 95% of all movements tended to increase slightly, depending on the length of simulation run. The mean number of high risk movements that occurred over the 100 km radius was 3.4.
Quantitative assessments of animal welfare are increasingly being used in the dairy industry. It is important to have good precision and accuracy within and among assessors. This study explored the effectiveness of a 3-d training workshop for animal-based measures (ABM) of welfare in dairy cows, in which 14 people were trained to evaluate 6 ABM, specifically hock injuries (HI), lameness (LM), body condition score (BCS), and udder, flank, and leg cleanliness (collectively CLN). All scoring systems were modified to a dichotomous outcome, acceptable or unacceptable. Acceptable HI included no swelling or hair loss, unacceptable HI included swelling or scab; acceptable BCS was >2 on a 5-point scale, unacceptable BCS was ≤2. Acceptable CLN was up to minor splashing, unacceptable CLN was distinct plaques to a solid manure plaque. Lameness was evaluated using locomotion score or in-stall lameness score (SLS) in tiestalls; unacceptable LM was ≥3 (lameness score) on a 5-point scale, where 3 equals mild lameness or ≥2 of 4 behavioral in-stall lameness score indicators were detected. Classroom instruction took place on d 1 of training. Day 2 consisted of group assessment of LM (n = 25 cows), and HI, CLN, and BCS (n = 30 cows), and individual assessment of HI, CLN, and BCS (n = 20 cows) were performed. Day 3 included individual assessments of HI, CLN, and BCS (n = 33 cows), and individual video assessment of LM (n = 27 cows). An additional training video for LM was sent to trainees 3 wk after the workshop, and another follow-up assessment of LM took place via video (n = 37 cows). Repeatability and accuracy of the trainees was assessed using Fleiss's κ (FK) and Byrt's κ (BK) to examine group-level inter-rater agreement and expert-trainee agreement, respectively. The kappa systems use a scale of poor (<0), slight (0.01 to 0.20), fair (0.21 to 0.40), moderate (0.41 to 0.61), substantial (0.61 to 0.80), or almost perfect (0.81 to 1.00). At the conclusion of the workshop, FK was 0.66 for HI and 0.43 for LM, and BK mean (and range) was 0.85 (0.63 to 1.00) for HI and 0.66 (0.56 to 0.85) for LM. Each trainee achieved perfect agreement for BCS [BK mean = 1.00 (1.00 to 1.00)] and each trainee achieved almost perfect agreement for CLN [BK mean 0.90 (0.82 to 0.94)]. After the follow-up video and 3 wk of experience, trainees achieved a FK of 0.66 and a BK mean of 0.74 (0.62 to 0.89) for LM. In conclusion, multiple assessors can achieve substantial agreement for ABM with adequate training.
The objective of this study was to estimate Canadian national milk quality parameters and estimate the bulk tank milk (BTM) prevalence of 4 mastitis pathogens, Staphylococcus aureus, Streptococcus agalactiae, Mycoplasma bovis, and Prototheca spp., on Canadian dairy farms. A questionnaire was sent to all Canadian dairy producers. Of the 1,062 producers who completed the questionnaire, 374 producers from across the country were visited and milking hygiene was assessed. Farm-level milk quality data for all Canadian dairy producers was collected from the provincial marketing boards and combined with the questionnaire and farm visit data. In addition, a BTM sample was collected either during the farm visit or by the marketing board in November of 2015 and was tested for 4 major mastitis pathogens using the PathoProof Mastitis Major 4 PCR Assay (Thermo Fisher Scientific Inc., Waltham, MA). Apparent herd-level prevalence was 46% for S. aureus, 6% for Prototheca spp., 0% for M. bovis, and 0% for Strep. agalactiae. Due to the low prevalence of M. bovis and Strep. agalactiae and a lack of significant factors associated with farms testing positive for Prototheca spp., an association analysis could only be carried out for Staph. aureus-positive farms. Factors associated with Staph. aureus-positive farms were not fore-stripping cows before milking (odds ratio = 1.87), milking with a pipeline system (odds ratio = 2.21), and stall bases made of a rubberized surface (mats and mattresses), whereas protective factors were using blanket dry cow therapy (odds ratio = 0.49) and applying a tag or visible mark on cows known to have chronic mastitis infections (odds ratio = 0.45). The Canadian national production-weighted geometric mean somatic cell count was determined to be 208,000 cells/mL. This is the first national dairy study conducted in Canada. Participating farms had higher milk yield; were more likely to have a loose housing system, parlor, or automated milking system; and had lower weighted mean BTM somatic cell count than the national level. Sampling larger farms with better milk quality means the apparent prevalence of the 4 mastitis pathogens likely underestimates the true levels.
The relationship between biosecurity and digital dermatitis (DD) was evaluated in 8,269 cows from a convenience sample of 39 freestall dairy herds. The hypothesis was that poor implementation of biosecurity was associated with higher within-herd prevalence of DD. All lactating cows were scored as negative or positive for DD at the hind legs during milking in the milking parlor. Information about biosecurity was obtained through questionnaires addressed to farmers, on-farm observations, and information from the Danish Cattle Database (www.seges.dk). These assessment tools covered potential infection sources of DD pathogens to susceptible cows (e.g., via animals, humans, manure, vehicles, equipment, and facilities). External and internal biosecurity measures were explanatory variables in 2 separate logistic regression models, whereas within-herd DD prevalence was the outcome. Overall DD prevalence among cows and herds were 24 and 97%, respectively; the within-herd DD prevalence ranged from 0 to 56%. Poor external biosecurity measures associated with higher prevalence of DD were recent animal purchase, access to pasture, lack of boots available for visitors, farm staff working at other dairy farms as well, hoof trimming without a professional attending, and animal transporters having access to cattle area. For internal biosecurity, higher DD prevalence were associated with infrequent hoof bathing, manure scraping less than 8 times a day, manure removal direction from cows to heifers, animal pens' exit without water hoses, manure-handling vehicle used in other activities, and water troughs contaminated with manure. These findings showed that improvements on biosecurity may be beneficial for controlling DD in dairy herds. The study is relevant for farmers facing problems with DD, as well as hoof trimmers, advisors, and veterinarians, who can use the results for optimized recommendations regarding biosecurity in relation to DD. Furthermore, our results might be considered by future studies investigating DD pathogen reservoirs and transmission routes.
The objectives of this study were to (1) quantify current reproduction management practices, and (2) assess the association between these practices and herd reproductive performance on dairy farms in Canada. A bilingual survey was developed, validated, and administered from March to May 2014 to collect general and reproduction management and performance measures [annual 21-d pregnancy rate (PR), 21-d insemination rate (IR), and conception risk (CR)]. Associations between management practices and reproductive performance measures were tested using linear regression models. A total of 832 questionnaires were completed online and by mail, representing a response rate of 9%. On average, farms had 77 lactating cows (median = 50) and 13 dry cows (median = 10), and Holstein was the most common breed (92% of herds). Lactating cow housing was tiestall on 61% of the farms, freestall on 37%, and bedded pack on 2%. The average voluntary waiting period was 58 d in milk (DIM). The main reproduction management practice per farm was defined as the means employed for >50% of inseminations. Farms reported their main reproduction management practice for first and subsequent inseminations, respectively, as visual estrus detection (51 and 44% of herds), timed AI (21 and 23% of herds), automated activity monitoring (AAM; 10 and 10% of herds), other management practice (bulls; 2 and 2% of herds), and a combination of management practices (16 and 21% of herds). On farms using visual estrus detection, cows were observed for signs of estrus on average 3.5 times per day, for an average total of 36 min/d. The most common use of reproductive hormones was to synchronize ovulation using Ovsynch (58% of the farms). Average PR, IR, and CR were 17.6, 44.1, and 40.5%, respectively. In linear regression analyses adjusted for confounders, pregnancy rate was significantly associated with geographic region, housing (tiestall: PR = 15.4%, freestall: PR = 17.6%), herd size (<50 lactating cows: PR = 16.2%, 50–100 cows: PR = 16.5%, >100 cows: PR = 17.8%), voluntary waiting period (≤60 DIM: PR = 17.6%, >60 DIM: PR = 15.9%), and frequency of insemination per day (once daily: PR = 16.6%, twice or more daily: PR = 18.1%). The main reproduction management practice at first and subsequent inseminations was divergently associated with IR and CR, but not with PR (visual heat detection: PR = 17.4%, timed AI: PR = 18.4%, AAM: PR = 17.1%, combined practices: PR = 18.2%).
Implementation of specific management strategies on dairy farms is currently the most effective way to reduce the prevalence of Johne's disease (JD), an infectious chronic enteritis of ruminants caused by Mycobacterium avium subspecies paratuberculosis (MAP). However, dairy farmers often fail to implement recommended strategies. The objective of this study was to assess perceptions of farmers participating in a JD prevention and control program toward recommended practices, and explore factors that influence whether or not a farmer adopts risk-reducing measures for MAP transmission. Semi-structured interviews were conducted with 25 dairy farmers enrolled in a voluntary JD control program in Alberta, Canada. Principles of classical grounded theory were used for participant selection , interviewing, and data analysis. Additionally, demographic data and MAP infection status were collected and analyzed using quantitative questionnaires and the JD control program database. Farmers' perceptions were distinguished according to 2 main categories: first, their belief in the importance of JD, and second, their belief in recommended JD prevention and control strategies. Based on these categories, farmers were classified into 4 groups: proactivists, disillusionists, deniers, and unconcerned. The first 2 groups believed in the importance of JD, and proactivists and unconcerned believed in proposed JD prevention and control measures. Groups that regarded JD as important had better knowledge about best strategies to reduce MAP transmission and had more JD risk assessments conducted on their farm. Although not quantified, it also appeared that these groups had more JD prevention and control practices in place. However, often JD was not perceived as a problem in the herd and generally farmers did not regard JD control as a " hot topic " in communications with their herd veterinarian and other farmers. Recommendations regarding how to communicate with farmers and motivate various groups of farmers according to their specific perceptions were provided to optimize adoption of JD prevention and control measures and thereby increase success of voluntary JD control programs.
Johne's disease (JD) is a chronic, infectious disease in cattle. Between 2010 and 2013, a voluntary JD control program was successfully launched in Ontario, Canada, including a Risk Assessment and Management Plan (RAMP) and JD ELISA testing of the entire milking herd. Over the last decade, the organic dairy sector has been growing. However, organic farming regulations and philosophies may influence the risk for JD transmission on Ontario organic dairy farms. The aim of this cross-sectional study was to investigate differences in JD ELISA test positive prevalence, risk factors for JD and recommendations for JD prevention between organic and conventional dairy herds in Ontario. RAMP results (i.e. RAMP scores and recommendations) and ELISA results were available for 2103 dairy herds, including 42 organic herds. If available, additional data on milk production, milk quality, and herd characteristics were gathered. Organic and conventional herds had a similar herd-level JD ELISA test-positive prevalence (26.2% and 27.2%, respectively). Organic herds (4.2%) had a higher within-herd JD ELISA test-positive prevalence compared to conventional herds (2.3%) if they had at least one JD test-positive animal on the farm. Organic farms had lower risk scores for biosecurity (9 points lower), and higher scores in the calving (7 points higher) and the calf-rearing management areas (4 points higher). After accounting for RAMP score, organic farms received fewer recommendations for the calving management area (Odds Ratio=0.41) and more recommendations in the adult cow management area (Odds Ratio=2.70). A zero-inflated negative binomial model was built with purchase of animals and the herd size included in the logistic portion of the model. Herd type (organic or conventional), colostrum and milk feeding practices, average bulk tank somatic cell count, and presence of non-Holstein breeds were included in the negative binomial portion of the model. Organic farms had a higher number of test positive animals (Count Ratio=2.02). Further research is necessary to investigate the apparent disconnect between risk factors and recommendations on organic dairy farms.
The objectives of this study were to describe the characteristics and motivations of producers who had implemented automated activity-monitoring (AAM) systems and to compare herd reproductive performance before and after the implementation of an AAM system and between herds with AAM and herds managing reproduction based on timed artificial insemination (TAI) or based on other programs. Freestall dairy herds located in Ontario and the western provinces of Canada and enrolled in Dairy Herd Improvement were surveyed through a mail questionnaire between April and July 2010. The data describe the characteristics and reproductive management practices of herds using AAM systems. A total of 505 questionnaires (29%) were returned. On average, 21-d pregnancy risk, conception risk, and 21-d insemination risk did not differ between herds managing reproduction based on an AAM system (18, 39, and 50%, respectively) or a TAI-based program (17, 38, and 49%, respectively). Herds that implemented an AAM system had a significant increase in annual pregnancy risk, from 15 to 17%, and insemination risk increased from 42 to 50%, whereas conception risk was unchanged (37 and 35%) following adoption of the system. The majority of respondents with AAM systems first used the system to manage reproduction in lactating cows. Most herds with AAM were performing artificial insemination twice per day, most commonly with an interval from the estrus alarm to artificial insemination of 7 to 12 h. The most commonly reported reason to adopt an AAM system was a desire to improve reproductive performance. These results support the findings from randomized trials that AAM-based programs can yield comparable reproductive performance to TAI-based programs.
Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.
Biosecurity at farm-level can often be poorly implemented, and lack of information has been cited by many studies as a potential explanation. Veterinary practitioners (VPs) and dairy advisors (DAs) play a central role in the provision of animal health and management services to dairy farmers. The objective of this study was to document and compare biosecurity-related practices and opinions across VPs and Das in Ireland. A selection of veterinary experts (VEs) from outside of Ireland was also surveyed.
Questionnaires were completed and response rates of 47% (VPs), 97% (DAs), and 65% (VEs) were achieved. Significant differences were identified in the promotion and implementation of biosecurity between VPs and DAs, with a higher proportion of VPs regularly receiving requests from (P = 0.004), and dispensing advice to (P < 0.0001), their farm clients. Communication between DAs and VPs was sub-optimal with over 60% of each group not in regular communication with each other. With regard to the main farmer motivation for biosecurity implementation, the majority of VPs (62%) prioritised external factors such as ‘economic benefit’ and ‘mandatory obligation’, while the majority of DAs prioritised health/animal-related factors (69%), which were similar to those of farmers (83.1%), although they remained significantly less likely (OR = 1.8) than farmers to choose such motivators (P = 0.005). Inconsistencies in the implementation of, and in opinions relating to, farm biosecurity were highlighted across all the groups surveyed emphasising the need for standardised information and improved communication.
The biosecurity status of 95 breeder-finisher pig herds was quantified using a risk-based weighted scoring system. Data relating to herd-, farmer- and production-characteristics and to the prophylactic use of antimicrobials were also collected. The average external biosecurity score (measures to prevent pathogens from entering a herd) was 65 (range, 45-89) and the average internal score (measures to reduce the within-herd spread of pathogens) was 52 (range, 18-87). External scores were positively associated with herd size, while internal scores were negatively associated with both 'age of buildings' and 'years of experience of the farmer', indicating that biosecurity is generally better implemented in larger herds, in more modern facilities and by younger farmers. External and internal biosecurity scores were positively associated with daily weight gain and negatively associated with feed conversion ratio of fattening pigs. Internal scores were negatively associated with disease treatment incidence, suggesting that improved biosecurity might help in reducing the amount of antimicrobials used prophylactically. This study demonstrates and quantifies a clear link between biosecurity and both production- and antimicrobial treatment-related criteria in pig herds.
A computer-based on-farm surveillance system of dairy cow abortion was presented as a means of improving diagnosis and knowledge of bovine abortion. Abortion was defined as fetal death between 42 and 260 days of gestation. Three measures of abortion were used: abortion density, estimated proportion aborting and age-specific hazard of fetal death. All three measures considered changes in the size of populations at risk due to censoring and abortion. Secular and seasonal rates and the testing of hypotheses concerning abortion were illustrated with data from seven California dairies that used on-farm computers. Potential biases and other considerations in abortion surveillance were discussed.
The objective of this study was to determine the herd-level effect of bovine leukemia virus (BLV) infection on dairy production, culling, and cow longevity. During routine herd testing, Dairy Herd Improvement Association technicians collected milk samples from about 40 cows from each of 104 randomly selected Michigan dairy herds averaging ≥120 milking cows and 11,686 kg of milk/yr. Milk samples were analyzed for the presence of anti-BLV antibodies by ELISA, and herd- and lactation-specific estimates of BLV prevalence were computed to determine which were the most predictive of herd milk production, culling rate, and cow longevity (proportion of cows in their third or greater lactation). On this basis, the herd BLV index (an unweighted mean BLV prevalence rate for lactation number 1, 2, 3, and ≥4) was selected as the measure of BLV prevalence that was the most highly associated with BLV economic impact. Step-down multivariate analysis was used to determine the extent to which any of 19 herd-level management variables may have confounded the association of BLV index and measures of herd economic impact (milk production and cow longevity). The BLV index was not associated with the 12-mo culling rate, but was negatively associated in the final multivariable model with the proportion of cows that were ≥third lactation, and was negatively associated with herd milk production. In summary, increased prevalence of BLV within Michigan dairy herds was found to be associated with decreased herd milk production and decreased cow longevity. Our results provide evidence that BLV infection is associated with herd-level economic impacts in high-performing dairy herds.
The objective of this cross-sectional study was to describe the application of management practices known to be associated with the prevention of bovine viral diarrhea virus (BVDV) infection on Indiana dairy farms and to determine the extent of BVDV vaccine use within Indiana dairy herds. The population in this study was Indiana dairy producers enrolled under the Indiana Premise ID list by the Indiana State Board of Animal Health (n=1600). During the fall of 2008 a questionnaire was mailed to Indiana dairy producers. Returned questionnaires were entered into a database and descriptive statistics were performed. A total of 208 questionnaires were found useful for analysis. Small herds (<100 head) constituted 60% of the sample population, 33% farms were categorized as medium herds (100-499 head) and finally 7% were large herds (>500 head). Most of the herds (68%) acquired their replacements from external sources (open herds); however, preventive measures against the introduction of BVDV into the farm such as purchased animal history, quarantine and BVDV testing were not commonly performed. Even though producers commonly reported the use of BVDV vaccines, not all animals groups were vaccinated within herds. This study highlights the aspects of management practices of BVDV control on Indiana dairy farms that need reinforcement. In particular, dairy producers should be made aware that vaccination should be complementary to a comprehensive biosecurity program.
Principal Component Analysis (PCA) Data - Notation - Examples Objectives Studying Individuals Studying Variables Relationships between the Two Representations NI and NK Interpreting the Data Implementation with FactoMineR Additional Results Example: The Decathlon Dataset Example: The Temperature Dataset Example of Genomic Data: The Chicken Dataset Correspondence Analysis (CA) Data - Notation - Examples Objectives and the Independence Model Fitting the Clouds Interpreting the Data Supplementary Elements (= Illustrative) Implementation with FactoMineR CA and Textual Data Processing Example: The Olympic Games Dataset Example: The White Wines Dataset Example: The Causes of Mortality Dataset Multiple Correspondence Analysis (MCA) Data - Notation - Examples Objectives Defining Distances between Individuals and Distances between Categories CA on the Indicator Matrix Interpreting the Data Implementation with FactoMineR Addendum Example: The Survey on the Perception of Genetically Modified Organisms Example: The Sorting Task Dataset Clustering Data - Issues Formalising the Notion of Similarity Constructing an Indexed Hierarchy Ward's Method Direct Search for Partitions: K-means Algorithm Partitioning and Hierarchical Clustering Clustering and Principal Component Methods Example: The Temperature Dataset Example: The Tea Dataset Dividing Quantitative Variables into Classes Appendix Percentage of Inertia Explained by the First Component or by the First Plane R Software Bibliography of Software Packages Bibliography Index
Critical to changing biosecurity practices on the farm is an individual assessment of those practices contributing to disease transmission. The purpose of this project was to assess, implement, and refine a biological risk management survey for use on large western United States dairy farms. Assessment tools developed by Iowa State University Center for Food Security and Public Health (Ames, IA) were refined using a focus group process and by testing them on 40 dairy herds in California. Each question was evaluated using standard criteria and producer responses. Some survey questions required refinement for clarity and others were considered unnecessary. New questions were added based on a biosecurity literature review, resulting in a new set of questions that can be used by extension educators and food animal veterinarians to help identify disease risk areas and educate dairy producers.
When designing mastitis-prevention and control programs, it is important to know the level of adoption of mastitis-prevention management practices and control programs and the herd-level prevalence of contagious mastitis pathogens. Our objectives were to estimate: (1) adoption of recommended mastitis-preventive management on Canadian dairy farms; (2) herd-level prevalence of contagious mastitis pathogens on Canadian dairy farms; and (3) associations of certain management practices with the isolation of Staphylococcus aureus from the bulk tank milk from Canadian dairy farms.
A retrospective cohort study involving 137 dairy herds randomly selected from all 390 participating in the Victorian Test and Control Program for bovine Johne's disease was undertaken to gain insight into the relationships between calf rearing practices and the occurrence of bovine Johne's disease on infected dairy farms. Each study farm was visited between July 2005 and January 2006 and a structured survey examining herd management and calf rearing practices was completed. The resultant data, along with information from annual herd testing for Johne's disease and records of clinical Johne's disease diagnosed in the herd, from May 1990 to March 2008, were analysed. Factors associated with time to the birth of the animal that was the first home-bred clinical case of Johne's disease or ELISA positive animal born after the second annual whole herd test in the herd were investigated using survival analysis methods. The publicly-subsidised Test and Control Program commenced in 1996. On the 1st of July 2003 the program was modified with more rigorous and externally audited calf rearing requirements introduced for all participants. The more stringent calf rearing requirements introduced in July 2003 appear to have translated into significantly reduced disease transmission within the infected study herds.
On-farm biosecurity is important for preventing the spread of several contagious animal diseases. In this study, biosecurity routines among Swedish farmers with livestock (cattle, pigs, sheep or goats) were examined through questionnaires posted by mail. Moreover, the use of protective clothing among professionals visiting farms, such as animal transporters and veterinarians, were investigated through assessments made by the farmers. Questionnaires were completed, partly or fully, by 518 farmers (overall response rate 34%). Possible associations between biosecurity routines and livestock species, geographic location and herd size were analysed. Large variations in biosecurity routines were found, both within and between groups, and some farms appeared to have a relatively high level of biosecurity. However, <40% of the farmers reported that they provide protective clothing for visitors, and 50% of farmers buying live animals introduced these directly into the herd without prior isolation. In general, a higher level of biosecurity was reported by farmers with herds with only pigs, when compared to farmers with cattle, sheep/goats or mixed species. A higher level of biosecurity was also reported by larger farms compared to hobby farms. Inconsistent biosecurity routines were reported, which was interpreted as a lack of knowledge of how different infections can spread and how this can be prevented. Furthermore, some replies indicated that the farmers perceived the risk of introduction of disease as low. According to the farmers' assessments, the use of protective clothing among professionals visiting farms varied considerably, both among different professions and within the same profession. On average, veterinarians and artificial insemination (AI) technicians got high scores in this assessment, while salesmen, repairmen and animal transporters were reported to seldom use protective clothing. Based on the findings, there is room for improvement of on-farm biosecurity. There is also a need to further investigate the motivators and constraints for altered routines among both Swedish livestock farmers and professionals visiting farms.
A better understanding of the epidemiology and pathogenesis of bovine virus diarrhoea virus (BVDV) has emerged in recent years. Fetal infections and in particular those resulting in birth of persistently infected calves are of central importance for the epidemiology of BVDV. A prevalence of persistently infected, viraemic animals of about 1% is found in Denmark and elsewhere by examination of randomly collected blood samples. A recent field study shows that 53% of randomly selected herds in an area in Denmark where BVDV is endemic had one or more persistently infected animals. Persistently infected cows may breed and will always transmit the infection to the calf. Such familial occurrence of persistent infection seems to be a fairly common phenomenon. Persistently infected cattle are important sources of infection to other cattle. Transiently infected cattle following experimental exposure will usually not transmit the infection by contact but this may not always apply to cattle after natural infection. Knowledge of the occurrence and potential for spread of virus from persistently infected bulls is reviewed. Virus is excreted with semen of both persistently and transiently infected bulls and BVDV may be transmitted by use of infected semen for insemination. The potential for spread of the infection through embryo transfer should be avoided by the use of adequate testing and controls.
To estimate direct and indirect contact rates on livestock facilities and distance traveled between herd contacts.
320 beef, dairy, goat, sheep, and swine herds, 7 artificial insemination technicians, 6 hoof trimmers, 15 veterinarians, 4 sales yard owners, and 7 managers of livestock-related companies within a 3-county region of California.
A questionnaire was mailed to livestock producers, and personal and telephone interviews were conducted with individuals.
Mean monthly direct contact rates were 2.6, 1.6, and 2.0 for dairies with < 1,000, 1,000 to 1,999, and > or = 2,000 cattle, respectively. Mean indirect contact rates on dairies ranged from 234 to 743 contacts/mo and increased by 1 contact/mo as herd size increased by 4.3. Mean direct monthly contact rate for beef herds was 0.4. Distance traveled by personnel and vehicles during a 3-day period ranged from 58.4 to 210.4 km. Of livestock arriving at sales yards, 7% (500/7,072) came from > or = 60 km away, and of those sold, 32% (1,180/3,721) were destined for a location > or = 60 km away. Fifty-five percent (16/29) of owners of large beef herds observed deer or elk within 150 m of livestock at least once per month.
Direct and indirect contacts occur on livestock facilities located over a wide geographic area and at a higher frequency on larger facilities. Knowledge of contact rates may be useful for planning biosecurity programs at the herd, state, and national levels and for modeling transmission potential for foot-and-mouth disease virus.
The overall purpose of this study was to provide information on animal and occupational health associated with the infection of a diary herd with Salmonella Muenster that would be useful in the management of dairy herds so infected. This retrospective, longitudinal report records a 2-year infection of a 140-cow dairy herd with S. Muenster, which was likely introduced by additions to the herd. Six cows aborted or had diarrhea due to salmonellosis in the last trimester of pregnancy. Additions to the herd and the presence of animals that had not received an Escherichia coli bacterin-toxoid were risk factors for salmonellosis. One neonate died, and 24 of 36 calves born between November 1998 and May 1999 had diarrhea by 1 mo of age. Initially, over 60% of the cows were fecal positive; within 6 months, all cows but I had become infected. The intermittent shedding of the organism and the eventual zero prevalence highlight the inappropriateness of extensive culling as an eradication strategy. Cultures of the bulk-tank milk filters were more sensitive than cultures of the bulk-tank milk samples at detecting S. Muenster. Two months after the index case, S. Muenster was cultured from the milk of 7.8% of the cows. Positive fecal or milk cultures were not associated with impaired health or production. The herd's milk was a zoonotic risk, but contact with infected animals was not. The organism spread easily between operations, likely via manure-contaminated clothing and footwear.
Recent world events have heightened awareness for the need to safeguard our livestock industries from disease agents. Biosecurity is the outcome of all activities undertaken to preclude introduction of disease agents into an animal population. The concepts of biosecurity are not new. Activities directed at ensuring biosecurity include controlling exposure and optimizing resistance. Programs for biosecurity must be individually tailored to specific situations to account for varying risks and perceptions of risk by decision makers. It is important for practitioners to take a holistic approach to disease control, considering the epidemiology of the disease in addition to the available vaccines and therapeutics.
An understanding of the driving forces of BVDV transmission can be gained by considering the reproductive rate, between individuals and between herds. The former determines the prospects for eliminating the infection from herds, and the latter is the key to persistence at the population level. In this paper, the relation between these two characteristics, their underlying parameters and measures and priorities for BVDV control are discussed. A general model for BVDV control is outlined, with bio-security, virus elimination and monitoring as three necessary consecutive elements, and with immunization as an optional step. A distinction is made between systematic and non-systematic approaches to BVDV control (where the former refers to a monitored and goal-oriented reduction in the incidence and prevalence of BVDV infection and the latter to where measures are implemented on a herd-to-herd decision basis and without systematic monitoring in place). Predictors of progress for systematic control approaches in general are discussed in terms of the abilities: to prevent new infections, to rapidly detect new cases of infection, to take action in infected herds and to gain acceptance by stakeholders. We conclude that an understanding not only of the biology, but also of the social factors - human behavior, the motives that makes stakeholders follow advice and the cultural differences in this respect - are important factors in forming recommendations on alternative strategies for BVDV control.
The aims of this study were to describe antibiotic use and biosecurity practices among Washington State dairy producers and to evaluate the effectiveness of a collaborative approach to promoting judicious antibiotic use on dairy farms. In collaboration with a statewide industry group, Washington State dairy producers participated in a written, self-administered survey in 2003. They were then provided several educational interventions followed by a second written survey in 2005. Sixty-five percent (381) of dairy producers completed the 2003 survey. The most commonly cited drugs used for disease treatment were penicillin, ceftiofur, and oxytetracycline. Participants also indicated significant preventive uses with 28% using medicated milk replacer. Most producers appeared to consider intramammary infusion at dry-off to be a treatment rather than a preventative practice. Twenty-three percent of initial respondents indicated at least one extra-label use of antibiotics, yet only half routinely consulted with a veterinarian when doing so. Most agreed that using written protocols for disease treatment could reduce errors, but less than one-third had protocols. After the educational intervention there was a tendency toward reduced use of antibiotic medicated milk replacer: 51% of producers who originally reported using medicated milk replacer discontinued this practice, whereas 12% of producers began using medicated milk replacer between the 2003 and 2005 surveys. Most reported that the resources and educational materials were useful. Areas where additional work is needed include reducing the use of medicated milk replacer, increasing veterinary involvement in antibiotic use decisions, implementing treatment protocols, enhancing biosecurity, and ensuring optimal cow and calf immunity.
Biosecurity for Canadian dairy farms: National standard. CFIA P0836-13
CFIA (Canadian Food Inspection Agency). 2013a. Biosecurity for Canadian dairy farms: National standard. CFIA P0836-13. Canadian
Food Inspection Agency, Ottawa, ON, Canada.
Biosecurity for Canadian dairy farms: Producer planning guide. CFIA P0862E-13
CFIA (Canadian Food Inspection Agency). 2013b. Biosecurity for Canadian dairy farms: Producer planning guide. CFIA P0862E-13.
Canadian Food Inspection Agency, Ottawa, ON, Canada.
Internet, Mail, and Mixed-Mode Surveys: The Tailored Design Method
- D A Dillman
- J D Smyth
- L M Christian
Dillman, D. A., J. D. Smyth, and L. M. Christian. 2008. Internet,
Mail, and Mixed-Mode Surveys: The Tailored Design Method. 3rd
ed. Wiley, Hoboken, NJ.