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Porcine reproductive and respiratory syndrome (PRRS) is an extremely contagious disease that causes great damage to the U.S. pork industry. PRRS is not subject to official control in the U.S., but most producers adopt control strategies, including vaccination. However, the PRRS virus mutates frequently, facilitating its ability to infect even vaccinated animals. In this paper we analyze how increased vaccination on sow farms reduces PRRS losses and when vaccination is profitable. We develop a SIR model to simulate the spread of an outbreak between and within swine farms located in a region of Minnesota. Then, we estimate economic losses due to PRRS and calculate the benefits of vaccination. We find that increased vaccination of sow farms increases the private profitability of vaccination, and also transmits positive externalities to farms that do not vaccinate. Although vaccination reduces industry losses, a low to moderate vaccine efficacy implies that large PRRS losses remain, even on vaccinated farms. Our approach provides useful insight into the dynamics of an endemic animal disease and the benefits of different vaccination regimens.

Porcine reproductive and respiratory syndrome (PRRS) is an endemic disease causing important economic losses to the US swine industry. The complex epidemiology of the disease, along with the diverse clinical outputs observed in different types of infected farms, have hampered efforts to quantify PRRS’ impact on production over time. We measured the impact of PRRS on the production of weaned pigs using a log-linear fixed effects model to evaluate longitudinal data collected from 16 sow farms belonging to a specific firm. We measured seven additional indicators of farm performance to gain insight into disease dynamics. We used pre-outbreak longitudinal data to establish a baseline that was then used to estimate the decrease in production. A significant rise of abortions in the week before the outbreak was reported was the strongest signal of PRRSV activity. In addition, production declined slightly one week before the outbreak and then fell markedly until weeks 5 and 6 post-outbreak. Recovery was not monotonic, cycling gently around a rising trend. At the end of the study period (35 weeks post-outbreak), neither the production of weaned pigs nor any of the performance indicators had fully recovered to baseline levels. This result suggests PRSS outbreaks may last longer than has been found in most other studies. We assessed PRRS’ effect on farm efficiency as measured by changes in sow production of weaned pigs per year. We translated production losses into revenue losses assuming an average market price of $45.2/weaned pig. We estimate that the average PRSS outbreak reduced production by approximately 7.4%, relative to annual output in the absence of an outbreak. PRRS reduced production by 1.92 weaned pigs per sow when adjusted to an annual basis. This decrease is substantially larger than the 1.44 decrease of weaned pigs per sow/year reported elsewhere.

Due to the highly transmissible nature of porcine reproductive and respiratory syndrome (PRRS), implementation of regional programs to control the disease may be critical. Because PRRS is not reported in the US, numerous voluntary regional control projects (RCPs) have been established. However, the effect of RCPs on PRRS control has not been assessed yet. This study aims to quantify the extent to which RCPs contribute to PRRS control by proposing a methodological framework to evaluate the progress of RCPs. Information collected between July 2012 and June 2015 from the Minnesota Voluntary Regional PRRS Elimination Project (RCP-N212) was used. Demography of premises (e.g. composition of farms with sows = SS and without sows = NSS) was assessed by a repeated analysis of variance. By using general linear mixed-effects models, active participation of farms enrolled in the RCP-N212, defined as the decision to share (or not to share) PRRS status, was evaluated and used as a predictor, along with other variables, to assess the PRRS trend over time. Additionally, spatial and temporal patterns of farmers' participation and the disease dynamics were investigated. The number of farms enrolled in RCP-N212 and its geographical coverage increased, but the proportion of SS and NSS did not vary significantly over time. A significant increasing (p

Porcine reproductive and respiratory syndrome (PRRS) is an extremely contagious disease that causes great damage to the U.S. pork industry. PRRS is not subject to official control in the U.S., but most producers adopt control strategies, including vaccination. However, the PRRS virus mutates frequently, facilitating its ability to infect even vaccinated animals. In this paper we analyze how increased vaccination on sow farms reduces PRRS losses and when vaccination is profitable. We develop a SIR model to simulate the spread of an outbreak between and within swine farms located in a region of Minnesota. Then, we estimate economic losses due to PRRS and calculate the benefits of vaccination. We find that increased vaccination of sow farms increases the private profitability of vaccination, and also transmits positive externalities to farms that do not vaccinate. Although vaccination reduces industry losses, a low to moderate vaccine efficacy implies that large PRRS losses remain, even on vaccinated farms. Our approach provides useful insight into the dynamics of an endemic animal disease and the benefits of different vaccination regimens.

Porcine reproductive and respiratory syndrome (PRRS) is an endemic disease causing important economic losses to the US swine industry. The complex epidemiology of the disease, along with the diverse clinical outputs observed in different types of infected farms, have hampered efforts to quantify PRRS' impact on production over time. We measured the impact of PRRS on the production of weaned pigs using a log-linear fixed effects model to evaluate longitudinal data collected from 16 sow farms belonging to a specific firm. We measured seven additional indicators of farm performance to gain insight into disease dynamics. We used pre-outbreak longitudinal data to establish a baseline that was then used to estimate the decrease in production. A significant rise of abortions in the week before the outbreak was reported was the strongest signal of PRRSV activity. In addition, production declined slightly one week before the outbreak and then fell markedly until weeks 5 and 6 post-outbreak. Recovery was not monotonic, cycling gently around a rising trend. At the end of the study period (35 weeks post-outbreak), neither the production of weaned pigs nor any of the performance indicators had fully recovered to baseline levels. This result suggests PRSS outbreaks may last longer than has been found in most other studies. We assessed PRRS' effect on farm efficiency as measured by changes in sow production of weaned pigs per year. We translated production losses into revenue losses assuming an average market price of $45.2/weaned pig. We estimate that the average PRSS outbreak reduced production by approximately 7.4%, relative to annual output in the absence of an outbreak. PRRS reduced production by 1.92 weaned pigs per sow when adjusted to an annual basis. This decrease is substantially larger than the 1.44 decrease of weaned pigs per sow/year reported elsewhere.

Between-farm animal movement is one of the most important factors influencing the spread of infectious diseases in food animals, including in the US swine industry. Understanding the structural network of contacts in a food animal industry is prerequisite to planning for efficient production strategies and for effective disease control measures. Unfortunately, data regarding between-farm animal movements in the US are not systematically collected and thus, such information is often unavailable. In this paper, we develop a procedure to replicate the structure of a network, making use of partial data available, and subsequently use the model developed to predict animal movements among sites in 34 Minnesota counties. First, we summarized two networks of swine producing facilities in Minnesota, then we used a machine learning technique referred to as random forest, an ensemble of independent classification trees, to estimate the probability of pig movements between farms and/or markets sites located in two counties in Minnesota. The model was calibrated and tested by comparing predicted data and observed data in those two counties for which data were available. Finally, the model was used to predict animal movements in sites located across 34 Minnesota counties. Variables that were important in predicting pig movements included between-site distance, ownership, and production type of the sending and receiving farms and/or markets. Using a weighted-kernel approach to describe spatial variation in the centrality measures of the predicted network, we showed that the south-central region of the study area exhibited high aggregation of predicted pig movements. Our results show an overlap with the distribution of outbreaks of porcine reproductive and respiratory syndrome, which is believed to be transmitted, at least in part, though animal movements. While the correspondence of movements and disease is not a causal test, it suggests that the predicted network may approximate actual movements. Accordingly, the predictions provided here might help to design and implement control strategies in the region. Additionally, the methodology here may be used to estimate contact networks for other livestock systems when only incomplete information regarding animal movements is available.

Due to the highly transmissible nature of porcine reproductive and respiratory syndrome (PRRS), implementation of regional programs to control the disease may be critical. Because PRRS is not reported in the US, numerous voluntary regional control projects (RCPs) have been established. However, the effect of RCPs on PRRS control has not been assessed yet. This study aims to quantify the extent to which RCPs contribute to PRRS control by proposing a methodological framework to evaluate the progress of RCPs. Information collected between July 2012 and June 2015 from the Minnesota Voluntary Regional PRRS Elimination Project (RCP-N212) was used. Demography of premises (e.g. composition of farms with sows = SS and without sows = NSS) was assessed by a repeated analysis of variance. By using general linear mixed-effects models, active participation of farms enrolled in the RCP-N212, defined as the decision to share (or not to share) PRRS status, was evaluated and used as a predictor, along with other variables, to assess the PRRS trend over time. Additionally, spatial and temporal patterns of farmers' participation and the disease dynamics were investigated. The number of farms enrolled in RCP-N212 and its geographical coverage increased, but the proportion of SS and NSS did not vary significantly over time. A significant increasing (p

Background: Climate-smart agriculture (CSA) addresses the challenge of meeting the growing demand for food, fibre and fuel, despite the changing climate and fewer opportunities for agricultural expansion on additional lands. CSA focuses on contributing to economic development, poverty reduction and food security; maintaining and enhancing the productivity and resilience of natural and agricultural ecosystem functions, thus building natural capital; and reducing trade-offs involved in meeting these goals. Current gaps in knowledge, work within CSA, and agendas for interdisciplinary research and science-based actions identified at the 2013 Global Science Conference on Climate-Smart Agriculture (Davis, CA, USA) are described here within three themes: (1) farm and food systems, (2) landscape and regional issues and (3) institutional and policy aspects. The first two themes comprise crop physiology and genetics, mitigation and adaptation for livestock and agriculture, barriers to adoption of CSA practices, climate risk management and energy and biofuels (theme 1); and modelling adaptation and uncertainty, achieving multifunctionality, food and fishery systems, forest biodiversity and ecosystem services, rural migration from climate change and metrics (theme 2). Theme 3 comprises designing research that bridges disciplines, integrating stakeholder input to directly link science, action and governance. Outcomes: In addition to interdisciplinary research among these themes, imperatives include developing (1) models that include adaptation and transformation at either the farm or landscape level; (2) capacity approaches to examine multifunctional solutions for agronomic, ecological and socioeconomic challenges; (3) scenarios that are validated by direct evidence and metrics to support behaviours that foster resilience and natural capital; (4) reductions in the risk that can present formidable barriers for farmers during adoption of new technology and practices; and (5) an understanding of how climate affects the rural labour force, land tenure and cultural integrity, and thus the stability of food production. Effective work in CSA will involve stakeholders, address governance issues, examine uncertainties, incorporate social benefits with technological change, and establish climate finance within a green development framework. Here, the socioecological approach is intended to reduce development controversies associated with CSA and to identify technologies, policies and approaches leading to sustainable food production and consumption patterns in a changing climate.

The proteasomal ATPase ring, comprising Rpt1-Rpt6, associates with the heptameric α-ring of the proteasome core particle (CP) in the mature proteasome, with the Rpt carboxy-terminal tails inserting into pockets of the α-ring. Rpt ring assembly is mediated

Immigration Reform: Implications for Agriculture.Democracy and Environmental Quality.Are International Beef Prices Converging and, if so, Why?

Brazil, the world's largest coffee exporter, encouraged efforts in the 1960s to form the International Coffee Agreement (ICA), which restricted total coffee exports via country export quotas. The quotas led to significant domestic quota rents in producing countries. This paper analyzes the effects of rent seeking in Brazil. The Brazilian Institute of Coffee (IBC), which was responsible for coffee policy, was the focus of rent seeking. The paper models the policy instruments used by the IBC, shows how rent seeking affected policy, industry efficiency and the distribution of rents, explains the causes and effects of IBC reforms in the late 1980s, and draws lessons from the experience.

The costs of living with wildlife are assessed using Namibian subsistence farmers' willingness to pay (WTP) for deterrents to attacks on crops and livestock as a measure of damage costs. A utility-theoretic approach jointly estimates household WTP for deterrent programs in two "currencies," maize and cash. This has a double payoff. Use of a non-cash staple increases respondent comprehension and provides more information about preferences, improving the accuracy of results. The household shadow value of maize is also identified. Significant costs from living with elephants and other types of wildlife are demonstrated. Compensation for farmers may be warranted on equity and efficiency grounds. Uncontrolled domestic cattle generate even higher costs to farmers than wildlife, highlighting the need to clarify property rights among these farmers.

Modern fruit sector development in Chile led to agricultural employment for women, though usually only as temporary workers and often at a piece rate. Nonetheless, fruit sector employment offered women access to income and personal fulfillment previously lacking. This paper links the fruit sector to improving female and family economic welfare in rural Chile and changing gender relations. Using a unique longitudinal data set, we examine women's decisions regarding labor force participation and employment, their earnings and contributions to household income, and their attitudes toward employment to understand how new opportunities are changing women, their households, and the rural sector.

Rent seeking is well known, but empirical evidence of its effects is relatively rare. This paper analyzes how the domestic and international rent seeking caused Brazil to provide coffee export tax rebates that transferred foreign exchange to coffee importers. Although Brazil was the world's largest exporter, it began to pay export tax rebates to selected coffee importers in 1965 and, by 1988, had paid rebates totaling $8 billion. Brazil explained these rebates as a mechanism to price discriminate among importers and expand exports within the context of the export quota imposed by the International Coffee Agreement. We show this explanation was invalid during most of the period. The net price fell for those who received rebates, causing Brazil to effectively transfer approximately $3 billion to foreign importers. The effects of the rebate policy were never recognized in Brazil, hidden largely by the complex nature of government intervention in the coffee sector.

Traditionally, the analysis of labor market adjustment refers to the interaction between the demand and the supply for labor, e.g., between employers and job seekers. The labor market is said to 'clear' when the wage and labor force participation adjust so that supply and demand are equal. However, it has been observed that the adjustment process in the agricultural casual labor market is often uneven and incomplete. This phenomenon has challenged economists to search for additional explanation of the workings of these markets (see for example Rosenzweig, 1986; Binswanger and Rosenzweig, 1981). Our study contributes to the literature by examining this issue using a Chilean data set collected by one of the authors in which pronounced seasonality is evident in both labor demand and labor supply, resulting in large changes in wages, participation and unemployment.The principal objective of this paper is to analyze the socio-economic and demographic factors that determine seasonal labor force participation, as well as the events that appear to be associated with labor market entry/exit of seasonal workers in order to enable us to understand the welfare implications of changes in economic behavior. We will analyze these phenomena in considerable detail and with additional econometric techniques attempting to shed additional light on seasonal adjustment in agriculture.A major strength of our study resides in the data set available. From January to March 1992, data were collected from 599 workers in three growing regions of Chile, who were then working in table grape processing sheds. For each worker, information was collected on measured productivity in a piece rate task in 1992, personal and family characteristics (e.g., age, sex, education, work experience, marital status, family composition, and family income), as well as on labor force participation, employment, type of work, incentive mechanism (wage or piece rate) and earnings for every day of calendar year 1991. Many of the workers surveyed held more than one job from more than one employer during the year. This rich longitudinal data set, including male and female workers, offers a new dimension to existing research on seasonal labor market analysis. We have data on a large number of factors that determine participation, employment, and earnings, and having a large number of observations throughout the entire year allows improved treatment of seasonal dynamics. We use econometric models for panel data to analyze the labor participation of individual seasonal workers, allowing for unobserved heterogeneity and consequently endogeneity/selection bias (Vella and Verbeek, 1999). In the process, we determine the expected wage of each worker for each day, based on that worker's human capital characteristics, and include the expected wage as a determinant of labor force participation. Preliminary results indicate that real wages fluctuate considerably over the year and that seasonal wage variation is an important aspect of labor market adjustment, contributing to a large change in labor force participation. The labor force participation rate of women is significantly more elastic to changes in their expected wage than is the labor force participation rate for men, though much of the difference in response appears to be due to the household roles that males and females play rather than gender differences per se. The labor force participation behavior of women is similar to that of men when the former are the heads of household. Although the labor force participation rates for seasonal workers vary greatly across seasons, we still find evidence of substantial open unemployment during the slack season. The analysis will also provide estimates of the premium earned per day for piece rate as opposed to wage work, and of differences in pay for male and female workers. The study will contribute longitudinal findings that will enhance our understanding of the dynamics of casual employment in agriculture.

The present study uses a socioecological-economic approach to identify community-level factors that influence the physical growth of young children. A multidisciplinary team of investigators collaborated to study the different prevalence rates of low growth among children living in 24 communities located in a tea plantation near Bandung, West Java, Indonesia. Measurements of weight and length were taken for 415 children between the ages of 6 and 18 months. Low growth prevalence rates were determined by calculating the number of children in each community who fell below two anthropometric cutoffs. Epidemiological and ethnographic methods were used to measure community infrastructure and services related to child growth. The principal finding is that a probit model using community-level variables successfully predicted the prevalence rates of low growth across communities. Quality community vaccination programs, child care services, environmental sanitation and latrines are associated with better child growth. The quantitative and qualitative evidence strongly suggests that community-level goods and services contribute substantially to health in early childhood.

The International Coffee Agreement (ICA) used export quotas to restrict coffee trade in order to increase and stabilize the international price. A model of domestic pricing policy is developed which shows that the producer price should have fallen in response to ICA quotas. Econometric analysis supports the hypothesis that use of quotas resulted in lower producer prices in most coffee producing countries. The income lost by producers was largely captured by governments and/or exporters to whom the governments assigned quota rights. Since coffee is produced by small farmers in most exporting countries, income distribution within those countries probably worsened.