Finally, sowmortality showed a significant increase in t + 1 with one more sow death than during the baseline period . In general, the indicators confirm that a PRRS outbreak affected several production stages for an extended period of time .The decline in weaned pigs marketed in week t − 1, although statistically insignificant, as well as changes in some performance indicators , suggest that the outbreak may have started in week t − 1, one week before it was reported. We therefore developed an alternative estimate of production losses that can be compared to the estimated loss if the outbreak is assumed to begin in week t. Eliminating t − 1 from the preoutbreak period led to estimation of a slightly higher baseline and, as a result, to a higher estimate of PRRS losses. Nonetheless, the difference between this estimate and our primary estimate is very small. Our primary estimate is that PRRS reduced weaned pig production per farm by 7.4% on an annual basis, leading to a decrease in output value per sow year of $86.6, or $367,521 per farm year for an average sized farm. If instead we assume the outbreak began in t −1 , the estimated reduction in weaned pig production was 7.6%, or $88.8 less per sow year and an average revenue loss of $376,773 among the farms studied.We analyzed the impact of a PRRS outbreak on weaned pig production in a set of sow farms that are part of the same swine firm in the US. We estimated the time profile of disease effects, identifying the weekly changes in output relative to a pre-outbreak baseline. We find that PRRS caused a 7.4% decline in production value measured over a one-year period. Correspondingly, 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 in another study . We note that total losses due to PRRS are likely to be greater than the revenue losses estimated in this study, how to cure cannabis fast as total losses must include cost increases associated with the disease, e.g., an increase in management expenses, bio-security investments, additional feed and veterinary inputs, plus a possible decrease in the weight or in the sales price of piglets . We found that weaned pig production declined in week t − 1, although statistically insignificant, as did several performance indicators. The data suggest that the average PRRS outbreak in this set of farms began at least one week before it was announced. This delay may be explained, at least in part, by the inability of producers to detect PRRS until animals begin to show explicit clinical signs, as well as the additional time needed to test and confirm the disease. The lag between the outbreak of disease and the appearance of clinical signs may be longer in farms using vaccination programs, as in our sample, where clinical signs may be subtle . It seems likely that some weaned pigs being shipped by these farms in week t − 1, when the disease was almost certainly present in these farms, but as yet unannounced, were infected with PRRS. The relatively slow identification of the disease means that animal movements out of infected premises must be a common source of disease spread. This is particularly important in sow farms that deliver wean pigs to different swine grower facilities each week. The rise in abortions was the strongest signal of PRRSV activity in our data. Increased surveillance, particularly to rising abortions, may allow farms to identify PRRS more quickly. Abortions were rising in the several weeks prior to the reporting of the outbreak in some of the farms in the sample.

Abortions rose significantly in t − 1 and then increased sharply in week t. The number of abortions declined rapidly and fairly monotonically following week t, with a slight uptick in weeks t + 10 to t + 13, and recovered to the baseline level by about week t + 20. Thus, to the extent that abortions are an indicator of an active virus in the sow herd, circulation of the virus appears to have ended about 20 weeks after it was reported. The uptick in weeks t + 10 to t + 13 suggests that the disease may have been infecting other susceptible cohorts of sows within the farms two to three months after the initial outbreak. The length of PRRS outbreaks, as well as their effects over time, is highly variable. For example, one study estimated effects of an outbreak during 12 weeks post detection , while another indicated that production of negative piglets was reached 27 weeks post infection . Our results demonstrate that PRRS has a negative effect on weaned pig production for a longer time than previously estimated. In our study, the estimated means of weaned pig production remained below the baseline throughout the 35 weeks that we are able to observe following the outbreak. Although the production of weaned pigs recovered to a level that is not significantly different from the baseline, we cannot definitively declare that there was no effect beyond week t + 35. Nonetheless, it appears that any continued effect is likely to be very small relative to the large effect occurring before week t + 35. We detected a consistent decrease in production until the 5th week after the outbreak report, followed by a non-monotonic recovery. All performance parameters followed a similar non-monotonic recovery pattern. Each indicator manifested a sharp worsening after the outbreak, followed by partial recovery and at least one mild period of deterioration. The dynamic up-and down impact of PRRS on weaned pig production was surprising. The precise causes are unclear, but the disease may spread more slowly and unevenly through the sow herd than anticipated, particularly on large units with multiple cohorts, in addition to possible incoming flows of replacement sows.

This effect might also explain the longer period of recovery in our study, versus another study that found production returned to the baseline in 16.5 weeks for cohorts vaccinated with an MLV and using herd closure as a control strategy . Other performance indicators provided consistent signals. Pre-weaning mortality increased sharply in weeks t − 1 to t + 1, declined to pre-outbreak levels by t + 10, and then oscillated about that level until about t + 24. Sow mortality increased in week t + 1 and remained above baseline levels until week t + 5. The increase in sow mortality could affect the age structure of the herd and consequently its production. Stillbirths increased until week t + 12, indicating that some infected sows carried damaged fetuses to birth. The number of stillbirths remained elevated through t + 36, suggesting that infected sows may have a higher probability of producing stillborn piglets for more than one pregnancy. The failure to conceive was followed by repeated services, which must have contributed to the lag in weaned pig production in later weeks. The numbers of pigs aborting or dying indicated that PRRS had its strongest effects on fetuses. PRRS kills relatively few sows and piglets, though the economic damage from sow mortality and/or their subsequently reduced productivity is important. Information regarding the strains of PRRS virus that affected each farm was not available for this study, as systematic sequencing of PRRS virus following outbreaks is still scarce. More than one strain might affect a given area, although in general genetic variation is more related to temporal rather than spatial variation . Using a sample of 16 farms may help capture the variability of PRRS outbreaks in the industry, assuming different strains may be affecting different farms. According to a number of studies, no vaccine prevents PRRS infection, but vaccination may reduce the risk of infection and may also reduce the intensity of outbreaks by reducing the amount of virus excreted by ill animals . Therefore, our results may show smaller damages than those that would be obtained for farms that do not vaccinate. Similarly, because the farms analyzed in this study belong to a firm with standardized protocols for disease management, our measure of PRRS’ impact could be smaller than would be measured on farms with poorer protocols. We developed and used a straightforward approach to quantify the dynamic effect of PRRS on weaned pig production within sow farms. We found that PRRS decreased weaned pig production for at least 35 weeks among the firms studied. The magnitude of PRRS’ impact, vertical growing weed as expressed in the duration and magnitude of the output decline, were both greater than anticipated. We found that recovery oscillated about a rising trend, i.e., recovery does not depict a clear monotonic increase in production, suggesting that farms suffered from a continuing circulation of the disease within the herd and/or a lingering effect on sows and piglets. Analysis of the underlying performance indicators provided additional insight regarding how PRRS affects farm output over time. Previous studies have utilized numerous assumptions to develop estimates of the total annualized losses to the swine industry due to PRRS . We have not attempted to replicate those studies. However, our results suggest PRRS may cause significantly higher losses on sow farms than has been estimated previously. Further, we believe that the losses identified in our farm sample are likely to be smaller than those on the average sow farm infected with PRRS. Nonetheless, we found substantial variation in performance among even a set of relatively standardized 16 farms. There is thus need for caution when using simple averages, as we often have done, rather than distributions across farms.Food companies have increasingly introduced products featuring farm practices as product attributes, with organic practices representing a leading example.

About 1,400 new organic products were introduced in 2009 and 3,000 in 2016 . To contribute to understanding the organic market, I explore econometrically buyer willingness to pay for carrots grown with organic practices relative to conventional carrots. I also export the demand for convenience and processing practices by exploring willingness to pay for fresh cut carrots relative to full sized carrots. Some food processing and marketing companies supply food products only from farm outputs produced with certain farm practices. For example, McDonalds and Walmart, have announced that within the next decade they will buy, use or sell only cage-free eggs . As of May 8, 2016, over 160 prominent food companies had announced that they will use only cage-free eggs, most by 2025 . Although not generally practiced by major retailers, many specialty markets and restaurants offer only or primarily organic food products.Governments also contribute to the demand shifts away from once conventional food products. For example, several U.S. states have introduced mandatory rules to eliminate conventional eggs from the in-state market. For example California and other states, including Massachusetts, Michigan, Oregon, and Washington, passed such laws . California has implemented mandatory cage-free housing for eggs consumed in California starting January 2022 as a part of the implementation of Proposition 12 . My model of government restrictions on food products that may be sold based on farm practices, which is applied to California’s Proposition 12 rules for pork products, shows how specific features of regulations affect market outcomes. Such product regulations may be imposed only on buyers within a specific jurisdiction but apply to farm practices outside that jurisdiction. Such regulations seem to be increasingly common and controversial, as reflected by the Hog industry challenge of Prop 12 before the U.S. Supreme Court . However, economists have not fully explored their impacts on prices and economic welfare, either within or beyond the regulating jurisdiction.The Prop 12 regulations on pork products allowed for sale in California specify mandates about how the breeding pigs are housed. The housing rules apply to sows that farrow pigs that produce pork to be sold to buyers in California. My model incorporates four empirical and regulatory features that determine economic impacts: California comprises about 9% of the market for North American pork; The regulations cover only some of the pork products from each hog. When a fraction of production becomes California compliant, the converting farms incurconversion costs and higher ongoing production costs; Segregation and traceability along the supply chain of hogs and pork destined for California is costly; and The quantity demanded for covered and non-covered pork products respond to relative prices, which are affected by costs of production, and pork demand may respond directly to the farm practice mandate.