Herd Type Research Articles

Herd typologies based on multivariate analysis of biosecurity, productivity, antimicrobial and vaccine use data from Danish sow herds

The use of antimicrobials in livestock constitutes an increasing global concern, and many countries pursue approaches to reduce the amount used, particularly in the pig production industry. The EU Commission has decided, due to environmental concerns, to phase out use of zinc oxide in pigs by 2022. This poses an additional challenge to efforts to reduce antimicrobial use (AMU) in European pig production.The pig production sector needs further information about how to comply with official AMU requirements without losing competitiveness. The most efficient approaches are likely to involve a combination of multiple factors. Therefore, the objective of this study was to explore multidimensional associations between biosecurity, productivity, vaccination and AMU.A cross sectional study was conducted using data from 160 Danish sow herds in 2014-2015. Biosecurity data were collected through computer-assisted telephone interviews using a pre-developed questionnaire (Biocheck.UGent®) supplemented with additional country-specific questions and translated into Danish. Herd-specific data, consisting of antimicrobial prescriptions, purchase of vaccines against five endemic infections, herd health status and one productivity measure (i.e. number of weaned piglets per sow per year) were extracted from various databases. Factor analysis was conducted on a subset of the data from 152 herds with sufficiently complete data. The identified factors were explained by evaluating data from herds with extreme loadings on the respective factor. The results were further discussed based on plots combining herd factor loadings on two factors at a time.Four factors were selected based on the break-point in the scree-plot. Factor 1 included herd type, herd size, and age of farm buildings. Factor 2 covered general biosecurity, including several internal and external biosecurity measures. Factor 3 represented preventive measures implying specific focus on avoiding introduction of ASF by foreign employees. Lastly, Factor 4 covered vaccination status, specifically regarding vaccination against Mycoplasma hyopneumoniae and Porcine Reproductive and Respiratory Syndrome virus. These factors were used to group the 152 sow herds into herd typologies. Feasible strategies aimed at improving health by reducing AMU without hampering animal welfare were identified and discussed for each typology.AMU and productivity correlated only weakly with other variables. This is probably due to limited variability in both these variables in study herds, which might be attributed to official restrictions on AMU, and a general high level of health and biosecurity in Danish sow herds.

Validation of a spatial liver fluke model under field conditions in Ireland.

Fasciola hepatica is the causative agent of fasciolosis, a global disease of a wide range of mammals, particularly sheep and cattle. Liver fluke infection causes annual losses estimated at around €2.5 billion to livestock and food industries worldwide. Various models have been developed to define risk factors and predict exposure to this liver fluke in ruminants in European countries, most of them based exclusively on data from dairy herds. The aim of this study was to validate a published theoretical baseline risk map of liver fluke exposure and cluster maps in Ireland, by including further explanatory variables and additional herd types that are spatially more widespread. Three approaches were employed: i) comparison of predicted and actual exposure; ii) comparison of cluster distribution of hotspots and coldspots; and iii) development of a new model to compare predicted spatial distribution and risk factors. Based on new survey data, the published baseline predictive map was found to have a sensitivity of 94.7%, a specificity of 5%, a positive predictive value of 60% and a negative predictive value of 38.2%. In agreement with the original model, our validation highlighted temperature and rainfall among the main risk factors. In addition, we identified vegetation indices as important risk factors. Both the previously published and our new model predict that exposure to Fasciola is higher in the western parts of Ireland. However, foci of high probability do not match completely, nor do the location of clusters of hotspots and coldspots.

Biosecurity and animal disease management in organic and conventional Swedish dairy herds: a questionnaire study

BackgroundGood 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.ResultsA 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.ConclusionsThe 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.

Quantifying the role of Trojan dams in the between-herd spread of bovine viral diarrhoea virus (BVDv) in Ireland

A compulsory national programme to eradicate bovine viral diarrhoea virus (BVDv) began in Ireland on 1 January, 2013. The objective of the current study was to quantify the role of Trojan dams (animal(s) not persistently infected (PI) with BVDv but carrying PI foetus(es) and introduced to the herd while pregnant with the PI foetus(es)) in the farm-to-farm spread of BVDv in Ireland, and to identify herd-level risk factors for producing or introducing a Trojan dam. The study population included all BVD+ calves born in Ireland between 1 January, 2013 and 31 December, 2015, along with their dams. BVD+ calves included all calves on the national programme database with an initial positive or inconclusive virus test, without a confirmatory re-test (status BVDPOS) and those with an initial positive or inconclusive test and a positive confirmatory test (status BVDPI). The Trojan status of dams was determined after considering their history of movement and of potential BVDV exposure, relative to a defined window of susceptibility (WOS; days 30–120 of gestation). During 2013–15, there were 29,422 BVD+ birth events to dams that were not themselves BVD+, including 2526 (8.6%) most-likely attributable to Trojan dams. The percentage of these birth events attributable to Trojan dams was significantly different (P < 0.001) between years, being 7.1% in 2013, 9.2% in 2014 and 10.6% in 2015. During 2013, in 9.9% of herds with one or more BVD+ birth to non-BVD+ dams, at least one of these births was attributed to a Trojan dam. In 2014 and 2015, the percentages were 11.8% and 13.3%, respectively. In 2013, in 7.8% of herds with one or more BVD+ birth to non-BVD+ dams, all of these births were attributable to Trojan dams. In 2014 and 2015, the percentages were 9.2% and 10.7%, respectively. A logistic GEE regression identified dam parity, herd size and an interaction between herd type and season as significant predictors for the birth of a BVD+ calf to a Trojan dam. Significant predictors for the sale of a Trojan dam from BVD+ herds included those selling more than one pregnant female and those with more than 2 BVD+ animals in the herd. Introduction of pregnant adult females is a potential source of BVD+ births in BVD-free herds and may add to the burden of infection in non-BVD-free herds. Addressing this route of transmission will be critical for herds that are now free of infection and wish to continue to purchase animals without introducing it.

Modeling livestock population structure: a geospatial database for Ontario swine farms

BackgroundInfectious diseases in farmed animals have economic, social, and health consequences. Foreign animal diseases (FAD) of swine are of significant concern. Mathematical and simulation models are often used to simulate FAD outbreaks and best practices for control. However, simulation outcomes are sensitive to the population structure used. Within Canada, access to individual swine farm population data with which to parameterize models is a challenge because of privacy concerns. Our objective was to develop a methodology to model the farmed swine population in Ontario, Canada that could represent the existing population structure and improve the efficacy of simulation models.ResultsWe developed a swine population model based on the factors such as facilities supporting farm infrastructure, land availability, zoning and local regulations, and natural geographic barriers that could affect swine farming in Ontario. Assigned farm locations were equal to the swine farm density described in the 2011 Canadian Census of Agriculture. Farms were then randomly assigned to farm types proportional to the existing swine herd types. We compared the swine population models with a known database of swine farm locations in Ontario and found that the modeled population was representative of farm locations with a high accuracy (AUC: 0.91, Standard deviation: 0.02) suggesting that our algorithm generated a reasonable approximation of farm locations in Ontario.ConclusionIn the absence of a readily accessible dataset providing details of the relative locations of swine farms in Ontario, development of a model livestock population that captures key characteristics of the true population structure while protecting privacy concerns is an important methodological advancement. This methodology will be useful for individuals interested in modeling the spread of pathogens between farms across a landscape and using these models to evaluate disease control strategies.

An epidemiological investigation of the early phase of the porcine epidemic diarrhea (PED) outbreak in Canadian swine herds in 2014: A case-control study

The first case of porcine epidemic diarrhea (PED) in Canada was diagnosed in January 2014 in Ontario, approximately 9 months after PED emerged in the United States. An early investigation of the Canadian outbreak suspected that the probable source of the virus was contaminated feed. The objective of this study was to evaluate the role of feed and other possible factors in the early phase of the PED outbreak in Canadian swine herds. The study period of interest for this case-control study was January 22nd to March 1st, 2014. A case herd was defined as a swine herd with a confirmed positive laboratory diagnostic test (RT-PCR) results for PED virus, along with pigs exhibiting typical clinical signs at the herd level during the study period.A questionnaire was administered to participating producers from the 22 Canadian swine herds enrolled (n = 9 case and n = 13 control herds). Case herd producers were asked to provide information from the initial day of onset of clinical signs and 30 days prior to that day. Control herds were matched to a case herd on the basis of province, herd type and approximate size. The period of interest for a control herd was matched to the initial day of clinical signs of PED for the case herd, along with the 30 days prior to this day. The questionnaire questions focused on herd demographics, biosecurity protocols, live animal movements onto and off sites, deadstock movements, feed and people movements for both the case and control herds. The questionnaire for control herds were based on their matched case’s period of interest, and together with case herds formed a matched stratum. Multivariable exact conditional logistic regression and mixed multivariable logistic regression models, with the matched stratum as a random effect, were used to assess the association between various risk factors and the odds of PED introduction into a herd. After adjusting for biosecurity practices, the odds of a PED occurrence was 38.1 (95% CI: 2.7–531.3) times greater for herds receiving feed from a single feed company that provided potentially contaminated feed (P = 0.007) than herds that did not. The number of live pigs delivered onto sites, semen deliveries and the frequency of deadstock pickups were not associated with PED status during the initial phase of the outbreak in univariable analyses. This study supports the role of potentially contaminated feed from a single feed company as a significant risk factor for PED viral introduction during the early phase of the Canadian outbreak.

Economic optimization of selective dry cow treatment

The objective of this study was to develop a mathematical model to identify a scenario with the lowest costs for mastitis associated with the dry period while restricting the percentage of cows to be dried off with dry cow antimicrobials. Costs of clinical and subclinical mastitis as well as antimicrobial use were quantified. Based on data from a large field trial, a linear programming model was built with the goal to minimize the costs associated with antimicrobial use at drying off. To enable calculations on minimizing costs of dry cow treatment on herd-level by drying-off decisions in an "average" herd, we created an example herd. Cows were projected on 3 different types of herds, based on bulk tank somatic cell count, and were categorized in groups based on parity and somatic cell count from the last test recording before drying-off. Economically optimal use of antimicrobials was determined while restricting the maximum percentage of cows dried off with antimicrobials from 100 to 0%. This restriction reveals the relationship between the maximum percentage of cows dried off with antibiotics and the economic consequences. A sensitivity analysis was performed to evaluate the effect of variation in the most important input variables, with the effect of dry cow antimicrobials resulting in a lower or higher percentage of clinical and subclinical mastitis depending on being dried off with or without dry cow antimicrobials, respectively, and the milk price. From an economic perspective, blanket dry cow treatment seems not to be the optimal approach of dry cow therapy, although differences between approaches were small. With lower bulk tank somatic cell counts, more dry cow antimicrobials can be omitted without economic consequences. The economic impact of reducing the percentage of clinical mastitis was found to be much larger than reducing the bulk tank somatic cell count. The optimal percentage of cows to be dried off with antimicrobials depends on the udder health situation, expressed as the bulk tank somatic cell count and the incidence of clinical mastitis. For all evaluated types of herds, selective dry cow treatment was economically more beneficial than blanket dry cow treatment. Economic profits of selective dry cow treatment are greater if bulk tank somatic cell count and clinical mastitis incidence are lower. Economics is not an argument against reduction of dry cow antimicrobials by applying selective dry cow treatment.

Seroprevalence of Toxoplasma gondii infection in ruminants in selected districts in Bangladesh.

To estimate the seroprevalence of toxoplasmosis and risk factors for seropositivity in sheep, goats and cattle in Dhaka, Mymensingh, Sirajganj and Chittagong districts in Bangladesh, 1104 sera samples (552 sheep, 300 goats and 252 cattle) were randomly selected and tested by an indirect enzyme linked immunosorbent assay (iELISA). The overall seroprevalence was 12.2% (135/1104), and was significantly (P=0.008) higher in goats (16.0%) than cattle (8.3%). The odds of seropositivity was 2.09 times (95% confidence interval [CI]: 1.23-3.67) higher in goats than cattle. In sheep, herd type, district and pregnancy status were significant risk factors. The odds of seropositivity was 2.1 (95% CI: 1.00-4.84), 7.29 (95% CI: 12.71-423.41) and 10.88 (95% CI: 5.42-23.41 times higher in sheep-only flocks, in Mymensingh district and in pregnant sheep than in mixed flocks, Chittagong district and non-pregnant sheep, respectively. In cattle, breeds and district were significant risk factors. The odds of seropositivity was 5.79 (95% CI: 1.13-24.62) and 4.29 (95% CI: 1.38-16.34) times higher in Holstein Friesian cross cattle and in Mymensingh district than in indigenous cattle and Chittagong district, respectively. This study indicates that exposure of sheep, goats and cattle to oocysts of T. gondii is widespread, suggesting that the consumption of raw and undercooked meat of these animals might be a source of human toxoplasmosis. Risk factor information can be used to design control programs to reduce exposure.

Survey of disbudding practice on Czech dairy farms

Disbudding is a routine practice in many dairy herds due to the effort to decrease the risk of injuries. Although the disbudding practice is regulated, it can vary among farms. The variation may be caused by many factors, such as herd size or type of breed, but also by farmers' perception of pain caused by disbudding. Hence, the aim of this study was to specify the disbudding practice on dairy farms in the Czech Republic and to assess these practices, including the use of pain mitigation medication, by breed, herd size, and sex of the disbudded calves. We analyzed data from 106 Czech dairy farms, which were collected by a trained interviewer at dairy meetings in 2014-2015. The farmers answered questions regarding the farm's basic characteristics, disbudding practice, and his/her attitude to the pain caused by disbudding. To test the influence of breed, herd size, and sex of disbudded calves on different variables, logistic regression models were used. Disbudding was performed in 92.5% of the surveyed farms; 63.3% of dairy calves were disbudded before 4 wk of age, and Czech Fleckvieh calves were 2.8 times more likely to be disbudded before 4 wk of age than Holstein calves. The hot-iron method was the most used method (69.4%). Calves were 4.5 times more likely to be disbudded by hot iron in herds where both heifers and bulls were disbudded than in herds where only heifers were disbudded. Most (>90%) surveyed farms did not use any pre- or post-procedure medication to mitigate the pain caused by disbudding. The disbudding procedure was performed mainly by farm personnel (94.9%), who were trained by a veterinarian or veterinary technician (46.9%) or by other farm personnel (37.8%) or were not trained (15.3%). Two-thirds of farmers observed behavioral changes in calves after disbudding. Most farmers estimated the pain caused by disbudding to be mild or moderate (20.4 or 45.9%, respectively) and 15.3% of farmers estimated it to be severe. Almost a quarter of interviewed farmers were unable to assess the duration of pain, 39.8% farmers estimated that the pain lasts only several minutes, and 20.4% estimated that the pain lasts up to 6 h. We detected a tendency that farmers of larger herds estimated pain duration to be shorter (odds ratio = 1.2). To improve calves' welfare, training is needed in disbudding practice, focusing on the advantage of pain mitigation.

Quantification of the probability of reintroduction of IBR in the Netherlands through cattle imports

In the Netherlands, the feasibility of a national control program for infectious bovine rhinotracheitis (IBR) is discussed. The aim of this program would be to achieve freedom from BoHV1 circulation (the causal agent of IBR), in the Dutch cattle population. When IBR would be eradicated, maintaining the free status is essential and insight in the probability of introduction of IBR through cattle imports is crucial. Values for input parameters such as the number of imports per country of origin, herd level prevalence and probability that a random imported animal per age category was either acutely or latently infected with IBR were quantified. A stochastic simulation model was built to predict the basic risk and the efficacy of four risk mitigating scenarios were evaluated. These scenarios involved testing prior to import, import restrictions and vaccination. The model output predicted that IBR infected animals are imported regularly. In an IBR free situation, 571 (5th and 95th percentile: 431–781) cattle herds will be newly infected. Latent infections account for most newly infected herds (77%). When the virus in the imported latently infected animal does not reactivate, subsequent impact of such infections remains limited. The model predicted that most of the herds infected by introduction of acutely infected animals would be veal herds. The scenario in which imports were only allowed from status 9 or 10 countries combined with testing cattle that originated from status 9 countries was most effective in reduction of the import risk to 70 herds per year. The scenario in which vaccination of calves was combined with testing of older cattle was estimated to reduce the number of newly infected herds to 82 per year. The stakeholders classified the latter scenario as most realistic because this scenario was deemed both feasible and rather effective. This study did not evaluate the impact of introduction of IBR in the cattle population, which might differ depending on the type of infection (acute vs. latent) and the herd type in which the virus is introduced. Moreover, when making the final decision about the optimal intervention, the economic perspective should also be taken into account. This study predicted that introduction of IBR will remain a risk for the Dutch cattle population after virus circulation is eliminated from the Netherlands. The import risk is reduced most in scenarios in which testing and vaccination are combined.

Genetic parameters of rumination time and feed efficiency traits in primiparous Holstein cows under research and commercial conditions

Feed efficiency has the potential to be improved both through feeding, management, and breeding. Including feed efficiency in a selection index is limited by the fact that dry matter intake (DMI) recording is only feasible under research facilities, resulting in small data sets and, consequently, uncertain genetic parameter estimates. As a result, the need to record DMI indicator traits on a larger scale exists. Rumination time (RT), which is already recorded in commercial dairy herds by a sensor-based system, has been suggested as a potential DMI indicator. However, RT can only be a DMI indicator if it is heritable, correlates with DMI, and if the genetic parameters of RT in commercial herd settings are similar to those in research facilities. Therefore, the objective of our study was to estimate genetic parameters for RT and the related traits of DMI in primiparous Holstein cows, and to compare genetic parameters of rumination data between a research herd and 72 commercial herds. The estimated heritability values were all moderate for DMI (0.32-0.49), residual feed intake (0.23-0.36), energy-corrected milk (ECM) yield (0.49-0.70), and RT (0.14-0.44) found in the research herd. The estimated heritability values for ECM were lower for the commercial herds (0.08-0.35) than that for the research herd. The estimated heritability values for RT were similar for the 2 herd types (0.28-0.32). For the research herd, we found negative individual level correlations between RT and DMI (-0.24 to -0.09) and between RT and RFI (-0.34 to -0.03), and we found both positive and negative correlations between RT and ECM (-0.08 to 0.09). For the commercial herds, genetic correlations between RT and ECM were both positive and negative (-0.27 to 0.10). In conclusion, RT was not found to be a suitable indicator trait for feed intake and only a weak indicator of feed efficiency.

Dairy calf management—A comparison of practices and producer attitudes among conventional and organic herds

Dairy calves are at high risk for morbidity and mortality early in life. Understanding producer attitudes is important for implementation of best management practices to improve calf health. The objectives of this study were to evaluate usage frequency and producer attitudes on key calf management practices between conventional and organic dairy operations. A cross-sectional survey was mailed to conventional and organic dairy producers in Ohio and Michigan that included questions on cow-calf separation, colostrum management, and vaccination use. The overall survey response rate was 49% (727/1,488); 449 and 172 conventional and organic producer respondents, respectively, were included in the final analysis. Binary, cumulative, and multinomial logistic regression models were used to test differences within and between herd types for management practices and producer attitudes. The majority of conventional (64%, 279/439) producers reported separating the calf from the dam 30 min to 6 h after birth. More organic (34%, 56/166) than conventional (18%, 80/439) producers reported separation 6 to 12 h after birth, and organic producers were more likely to agree time before separation is beneficial. Few conventional (10%, 44/448) and organic (3%, 5/171) producers reported measuring colostrum quality. Most conventional producers (68%, 304/448) hand-fed the first feeding of colostrum, whereas the majority of organic producers (38%, 69/171) allowed calves to nurse colostrum. Last, 44% (188/430) of conventional producers reported vaccinating their calves for respiratory disease, compared with 14% (22/162) of organic producers; organic producers were more likely to perceive vaccines as ineffective and harmful to calf health. Thus, the usage frequency and perceived risks and benefits of calf management practices vary considerably between conventional and organic dairy producers. These findings provide helpful information to understand decision making at the herd level regarding key calf management and health practices, regardless of production systems.

Economic Analysis of the Policy for Accreditation of Dairy Farms Free of Bovine Brucellosis and Tuberculosis: Challenges for Small and Large Producers in Brazil

AbstractOne of the cornerstones of the National Program for Control and Eradication of Bovine Brucellosis and Tuberculosis in Brazil is the voluntary accreditation of free herds. We developed a stochastic cost–benefit analysis model for two types of dairy herds (high yield Holstein‐Zebu crossbred females and lower productivity smaller scale herds) to identify the technical and economic constraints of this process. The initial prevalence of infected animals and the impact of the disease in the structure and performance of the herd were derived from secondary data. Information on the costs and benefits of herd sanitation were compiled into a cost–benefit model at the herd level. The last step consisted of a scenario simulation to evaluate the impact of alternative policies to the certification process. For each scenario, we calculate the probability over time of a Benefit–Cost Ratio greater than 1 and of an Internal Rate of Return above 1% (the discount rate used in the model). Results show that larger and more intensive dairy farms, and also herds affected by brucellosis compared with tuberculosis‐positive herds, are more likely to achieve financial gains from the certification investment. The compensation for culled animals is important in the initial phase of herd sanitation and the premium payment on milk would help farmers to achieve a return on the investment over time. The model can be adapted to different and dynamic production, epidemiological and economic settings.

A quantitative risk-analysis for introduction of Bovine Viral Diarrhoea Virus in the Netherlands through cattle imports

Many countries have implemented control programmes aiming to eradicate Bovine Viral Diarrhoea Virus (BVDV). After obtaining the free status, a risk of re-introduction of the virus through import may remain. Therefore the risk of introduction of BVDV through cattle imports in the Netherlands was quantified and the effectiveness of subsequent intervention measures was assessed.Data, literature and expert opinion were used to estimate values for input parameters to feed a stochastic simulation model. The probability that BVDV was imported was differentiated into persistently infected (PI) cattle, trojan cows that transmitted the virus vertically resulting in a PI foetus (TR) and transient infected cattle (TI). The import risk was stratified to beef, dairy, small scale, suckler, trade, veal and young stock herds. The intervention scenarios that were evaluated consisted of virus testing, a combination of virus testing and antibody testing in pregnant cows, abolishment of imports from high risk countries (i.e. countries with a BVDV prevalence >15%) and a combination of import restrictions and testing prior to import.Each year, 334 (5th and 95th percentile: 65–902) Dutch cattle herds were estimated to be infected with BVDV through import. Veal herds account for most infections associated with import (87%), whereas in the other herd types, only 9 beef, 6 dairy, 2 small scale, 16 suckler, 10 trade and 2 young stock herds are infected through imports per year. Import of PI cattle is the most important risk for introduction in veal herds, while import of TR cows is the main source of BVDV introduction in dairy, small scale and suckler herds. With the intervention scenarios, the number of BVDV infected herds in the Netherlands could be reduced to 81 and 58 herds per year when respectively virus testing or a combination of virus and antibody testing was applied or to 108 herds when import from high risk countries was abolished. With the scenario in which both import from high risk countries was abolished combined with virus and antibody testing, the number of BVDV infected herds could be reduced to 17 herds per year. The risk assessment showed that BVDV is regularly imported in the Netherlands. The import risk can effectively be reduced by implementing diagnostic testing prior to import and only import cattle with a favourable result, eventually combined with certain trade restrictions.

Transmission dynamics of lumpy skin disease in Ethiopia.

Lumpy skin disease (LSD) is a severe disease of cattle caused by a Capripoxvirus and often caused epidemics in Ethiopia and many other countries. This study was undertaken to quantify the transmission between animals and to estimate the infection reproduction ratio in a predominantly mixed crop-livestock system and in intensive commercial herd types. The transmission parameters were based on a susceptible-infectious-recovered (SIR) epidemic model with environmental transmission and estimated using generalized linear models. The transmission parameters were estimated using a survival rate of infectious virus in the environment equal to 0·325 per day, a value based on the best-fitting statistical model. The transmission rate parameter between animals was 0·072 (95% CI 0·068-0·076) per day in the crop-livestock production system, whereas this transmission rate in intensive production system was 0·076 (95% CI 0·068-0·085) per day. The reproduction ratio (R) of LSD between animals in the crop-livestock production system was 1·07, whereas it was 1·09 between animals in the intensive production system. The calculated R provides a baseline against which various control options can be assessed for efficacy.

GPS tracking cattle as a monitoring tool for conservation and management

The emergence of GPS technology has resulted in significant advances in the ease and flexibility of studying animal movement patterns, yet barriers remain to the widespread use of GPS units for animal tracking. Here, we developed a low-cost, logistically simple approach, deploying small and inexpensive GPS units to monitor cattle movements and habitat use and to assess the impact of cattle grazing on vegetation. Cattle were collared with i-gotU loggers to track fine-scale and broad-scale movements within an integrated ecosystem (cattle and wildlife) in Laikipia, central Kenya. At the fine scale, cattle exerted a significant impact on vegetation quantity and quality; increasing grazing intensity showed a negative relationship to grass height, but a positive correlation to green-up after rain. At the broad scale, cattle movement density varied notably by herd type and habitat availability, with acacia woodland and savanna grassland habitats used most predominantly. Overall, these small GPS loggers provided a flexible and relatively cheap method of tracking cattle movements, and demonstrated potential for collaring of cattle as a tool for monitoring ecosystem health and assisting management decisions.

Economic Analysis and the Determinants of Pig Production in Ogun State, Nigeria

Abstract This study examined the economics and determinants of pig production in Ogun State, Nigeria using Obafemi Owode and Odeda Local Government in Ogun State, Nigeria where the enterprise is most prominent. The data used for the study were obtained from 60 respondents as there are very few farmers into this business in the state compared to other livestock production. Pig farmers were sampled through snowball sampling technique. The data collected were analyzed with descriptive statistics, budgetary, and Ordinary Least Square regression model. Results from the study revealed that the mean age of the respondents was 36.6 years and they were predominantly (81.7 %) male. Most (68.3 %) of the farmers had no access to credit with half of them married. On the cost and returns, returns on investment were positively associated with herd size, breed, and type of management system in the study area. When controlling for years of production experience and herd size, with every 1 naira increase in variable costs, the return on investment decreased by ₦0.879 ≈ $0.0044 (P &lt; 0.01). Similarly, when controlling for herd size and variable costs, with every 1 year of increase in production experience, the return on investment increased by ₦1.85 ≈ $0.0092 (P &lt; 0.01). When controlling for number of years of production experience and variable costs, with every 1 naira increase in cost of stock, the return on investment increased by ₦1,652.74 ≈ $8.22 (P &lt; 0.05). Lastly, when controlling for number of years of production experience and variable costs, every increase of herd size of 1 pig resulted in a return on investment of ₦1, 502.14 ≈ $7.47 (P &lt; 0.01). Level of pig production experience, herd size, variable costs items, cost of stock, and access to credit had significant influence on the production of pig in the study area. The study therefore recommends subsidization of input costs, the need for extension officers or experts to educate less experienced farmers on pig production and effective extension services targeted at raising technical knowledge of pig farmers towards effective productivity and profitability.

Patterns of calving and young stock movement in Ireland and their implications for BVD serosurveillance

The Republic of Ireland has a national eradication programme for bovine viral diarrhoea virus (BVDv) based on tissue-tag testing of calves to identify persistently infected animals (PIs). It has been proposed that serological testing of a sample of home-bred young stock would be a more cost effective surveillance mechanism than continued tissue-tag testing in herds which have previously been found to be BVD-free. These animals would have to be at least 6 months of age to avoid interference from maternal antibodies in test results. To examine the potential practicality of this system, we identified birth profiles and movements of calves born in Ireland during 2014 and 2015. We found that birth profiles for both beef and dairy animals were more evenly distributed throughout the year than often assumed, which should be borne in mind when evaluating the suitability of a single round of serological testing in the autumn for every herd. A large amount of movement was identified, with approximately 43% of calves experiencing a move before they reached 10 months of age, including moves to another Irish herd, to a knackery, to export, or to slaughter. Approximately 19% of calves had moved to other breeding herds in Ireland within this period. There were distinct patterns according to movement type, month of birth and herd type. The majority of herds moved either all or none of their calves in the first 10 months of life. These results indicate that young stock serological testing is unlikely to be an appropriate surveillance mechanism for all BVDv-free herds, as (i) many herds would not be able to supply a large enough sample of suitably aged home-bred young stock at a single point in time and (ii) PIs which would have been picked up by tissue-tag testing soon after birth would have moved from their home herd, to infect other herds, before serological testing could be conducted.

Stock Splits and Informational-Based Herding

This paper investigates the relation between institutional herding and stock splits. We use data on buying and selling activity of US institutional investors, from 1994 to 2005. We compute the abnormal correlation of trades among institutional investors in companies that have announced a stock split, compared to nonsplitting rms. The results show a signicant level of convergence of behavior, adjusted for common market factors, in both samples. Decomposing the correlation of trades into the contributions of several types of herding, we nd signicant impact of informational-based herding for splitting companies. The latter also motivates the dierence between the two groups. We also observe herding has a signicant stabilizing eect on the future returns of splitting companies. These results are consistent with an informational-based hypothesis of stock splits.

Temporal trends in the retention of BVD+ calves and associated animal and herd-level risk factors during the compulsory eradication programme in Ireland

The national BVD eradication programme in Ireland started on a voluntary basis in 2012, becoming compulsory in 2013. The programme relies on accurate identification and prompt removal of BVD+ calves. However, a minority of herd owners have chosen to retain BVD+ animals (defined as still being alive more than seven weeks after the date of the initial test), typically with a view to fattening them to obtain some salvage value. During each year of the programme, additional measures have been introduced and implemented to encourage prompt removal of BVD+ animals. The objective of this study was to describe temporal trends in the retention of BVD+ calves and associated animal and herd-level risk factors during the first three years of the compulsory eradication programme in Ireland.The study population included all BVD+ calves born in Ireland in 2013–2015. A parametric survival model was developed to model the time from the initial BVD test until the animal was slaughtered/died on farm or until 31 December 2015 (whichever was earlier). A total of 29,504 BVD+ animals, from 13,917 herds, were included in the study. The proportion of BVD+ animals that were removed from the herd within 7 weeks of the initial test date increased from 43.7% in 2013 to 70.3% in 2015. BVD+ animals born in 2015 had a much lower survival time (median=33days) compared to the 2013 birth cohort (median=62days), with a year on year reduction in survival of BVD+ calves. In the initial parametric survival models, all interactions with herd type were significant. Therefore, separate models were developed for beef and dairy herds. Overall the results of the survival models were similar, with birth year, BVD+ status, herd size, county of birth and birth month consistently identified as risk factors independent of herd type (beef or dairy) or the numbers of BVD+ animals (single or multiple) in the herd. In addition, the presence of a registered mobile telephone number was identified as a risk factor in all models except for dairy herds with a single BVD+, while the sex of the BVD+ calf was only identified as a risk factor in this model.Significant progress has been made in addressing the issue of retention of BVD+ calves, however, there is a need for further improvement. A number of risk factors associated with retention have been identified suggesting areas where future efforts can be addressed.